Monday 13 March 2017

Petroleum Exploration Society of Australia Distinguished Lecture Tour

The 2016 Australian Stress Map, summarised into average stress orientations in 29 geological provinces in Australia and New Guinea.


It is my great pleasure to have been invited to give a distinguished lecture and course tour for the Petroleum Exploration Society of Australia (PESA). This tour will be held throughout the rest of March, and starts this week in Sydney and Melbourne, before being followed by visits to Perth, Adelaide and Brisbane in the following weeks. The main focus of the tour is to give courses on the two topics I specialize in: Overpressures and Pore Pressure Prediction, and Petroleum Geomechanics.

Each course is designed to provide participants with the solid foundations and understandings of how geomechanics and pore pressure analysis are undertaken in the oil-patch. In particular, the courses will focus on the many significant and important exploration and production applications of geomechanics and pore pressure, as well as highlighting some of the many traps and pitfalls that are commonly encountered.

Geomechanics and pore pressure prediction are often taught upon a foundation of rock physics or petroleum engineering, and the underlying mathematics of these disciplines (which is critical for expert practitioners to understand) can often be quite daunting. However, this course is unusual in that it aims to strip away a lot of the maths and, instead, really focus on the geological aspects of geomechanics and pore pressure. After all, the answer to most questions in geoscience ultimately comes back understanding the rocks – so this course is uniquely designed to communicate the principles and applications of geomechanics and pore pressure analysis in a way that can be understood by all geoscientists.

Another key difference of this course is that it will be taught with a regional focus. The vast majority of published literature in pore pressure and geomechanics comes out of the USA, and pore pressure prediction, in particular has a habit of being extremely ‘Gulf of Mexico centric’. But, the lessons from the GoM and US often cannot be directly applied to the very different geological environments we see in Australia and South East Asia. So, just as this course is being founded on understanding the geology underlying pore pressure prediction and geomechanics, the course will also focus on the lessons learned from Australia and SE Asia.

In addition to giving these courses, I have also been invited to give distinguished lectures at PESA lunch and evening events in Sydney, Melbourne, Perth and Adelaide. So, I thought that I’d write a post introducing these lectures.

Each state was offered a list of six topics to choose from. Much to my delight, each of the four states picked a different topic, and so the lecture tour will consist of the following talks.
  1. The present-day stress field in sedimentary basins (Sydney, 14th March).
  2. Did drilling cause the ‘Lusi’ mud eruption of East Java? (Melbourne, 15th March).
  3. The Australian Stress Map Project: implications for exploration and production (Perth, 23rd March).
  4. A fresh look at pore pressure prediction: using ‘play-based pore pressure prediction’ to identify successful new play concepts (Adelaide, 28th March).

 Sadly, none of the states picked my favourite offered talk – a Dr Seuss-inspired talk entitled ‘Oh? The Outcrops You’ll Go!’. This was definitely the most fun lecture of my career to write, and takes people on a tour of amazing outcrops from around the world, while being presented entirely in Seussian rhythmic rhyme (you can read it here, and even listen to it on YouTube). Oh well! I’m sure I’ll get to give this one again sometime soon!

I look forward to meeting lots of industry professionals all around Australia throughout the rest of March!


Wednesday 14 December 2016

Oh! The Outcrops You'll Go! A Dr Seuss Inspired Geological Adventure



Well, its the end of 2016, and it is getting pretty hard for many of us to find positives from this year. Like so many other geologists right now, I am out of work, after getting laid off from a job that I loved. It does not feel like a very merry Christmas!

Despite it being a really rubbish time at the moment, when I think about it, there really is nothing else I’d rather be than a geoscientist, and I think most geos feel the same way. We are all passionate about the interesting science that we do. For me, I know that I have always been fascinated with the Earth, right from when I was a kid. I really was a big science nerd at school! When I was 14, I built a polariscope to look at how stresses are transmitted through materials. The following year I built a horizontal pendulum seismograph and ran it in our basement in South Australia for several months – and it worked! I picked up dozens of earthquakes from as far away as Alaska. Now, here I am, almost 25 years later, and little has really changed. I am still fascinated with, and learning about, the same things – stresses, and faulting and earthquakes and geomechanics. I still love what I do.

So, about a year ago, I wrote this talk as a way reminding myself and others why we love being earth scientists. Coming up to the end of 2016, I thought that it might be a good time to dust it off and share it with others.

I was inspired by Dr Seuss because, let’s face it, his rhythmic and rhyming stories, filled with silliness, are pretty awesome!  I thought about how cool it might be to try and do something similar on geology. However, I also quite liked one particular story about how Dr Seuss, or more properly, Dr Theodor Seuss Geisel, got his ‘big break’, and I think that his story is a good lesson for others, like me, that are feeling ‘redundant’.

The world actually came very close to never experiencing Dr Seuss’ wonderful stories. Dr Seuss’ first piece of children’s poetry was “And to think I saw it on Mulberry Street”, which he wrote while travelling to America by ship. Apparently, it was the constant beat of ships engines that inspired the famous rhythmic nature of his children’s poems. Yet, when he wrote this first piece of poetry, he couldn’t get it published. He said that around 40 publishers rejected the book. The story goes that he was actually on his way home to burn the manuscript when he had a chance encounter with a former university classmate who managed to help him, finally, get it published. So, it was really just perseverance and luck, as well as having a good professional network, that got him his big break, and allowed his delightful gifts to be shared with the world.

I think this resilience and perseverance is reflected in my personal favourite Dr Seuss book (and his final book): Oh! The places you will go! It is a great tale of how life and the world are fantastic and exciting, and that you can forge your own path. But the story also describes how life goes through its ups and downs, and the need to face and press through life’s challenges - like the downturn so many of us are currently in.

So, that is how this talk came about. I thought, why not talk about some of the spectacular geological sites that I’ve had the pleasure of visiting over my career. I thought this might be a nice way of trying to remind us all of why we love what we do, even when things are as glum as they currently are.

So, I hope you will find my Dr Seuss inspired ‘geological bed-time story’ interesting, as well as a bit of fun, and I hope that we all continue to be passionate about the geosciences, no matter how down and gloomy things may get.

Click on the video link below to hear an ~10 minute narrated version of my Dr Seuss geology talk, or read it yourself in the slides below (but don't forget to read in Dr Seuss rhythmic rhyme!).


Narrated Video


Story Book Version:





































Monday 12 December 2016

The World Stress Map – 2016 Release





The latest version of the World Stress Map Project has been officially released this week. This is the 30th anniversary of the project, and sees a big boost in data over the prior release in 2008. The latest version of the World Stress Map contains 42870 stress data records, which is approximately double that of the prior release, and about 10 times more than the first release over 25 years ago.


The 2016 Release of the World Stress Map

The World Stress Map Project started back in 1986, and was the brainchild of Professor Karl Fuchs and the International Lithosphere Programme, who asked Mary-Lou Zoback to head up a 5-year global effort to map out the state of tectonic stress in the Earth’s lithosphere. The initial results from over 30 researchers were published in an awesome 1992 issue of the Journal of Geophysical Research. Karl Fuchs and the WSM deputy leader, Dr Birgit Muller, then managed to get the project continued through the Heidelberg Academy of Sciences, with a research team based in Karlsruhe running the project until 2008. This phase of the project culminated in a 2010 special issue of Tectonophysics. Since 2008, the project has been based at the GeoForschungsZentrum in Potsdam, and led by Professor Oliver Heidbach, and is a part of the ICSU World Data System. The project remains a huge global collaborative effort, with contributions from dozens of researchers.



One of the fantastic things about the World Stress Map project is that it is completely free and public. All the data, as well as maps, software and interpretation guidelines are freely and publicly available. It is quite easy to make your own customised stress maps, and you can even download the .kmz file and put the stress map into GoogleEarth!



The 2016 release sees not just a doubling of stress data, but a large increase in petroleum industry data. Since 2003, the WSM has worked hard to put more petroleum industry data in the database, and the latest release sees particularly big increases in data in Australia, Canada, Great Britain, Iceland, Texas, Oklahoma, Switzerland, China, Italy and New Zealand. This is on top of the big increases in petroleum data from Southeast Asia, Australia, Germany, Egypt, West Texas and other areas in the 2008 version. The World Stress Map Project now contains over 7100 data points from wells. I am particularly proud of my recently completed PhD student, Dr Mojtaba Rajabi, for his amazing contribution in this big increase in data.



As ever though, there are still numerous conspicuous gaps in the World Stress Map. There is currently no to little data in the WSM from places such as the Middle East, Russia, Northern Africa and Brazil – all countries with large petroleum industries, but where data has not been made publicly available.



If you are interested in contributing to the World Stress Map Project, or would like the WSM t undertake stress analysis research on data you may have, please get in touch with the WSM or I!

Friday 12 August 2016

10 Years of the Lusi Mud Volcano Disaster – Part 3A: Was the Lusi Disaster Triggered by a Drilling Accident? Setting the Scene….

By Mark Tingay, @MarkTingay

The Lusi mud volcano, shortly after it's birth on the 29th of May 2006, with the TMMJ-04 rig that was drilling the Banjar Panji-1 well sited less than 150 meters away.

Foreword:

This is the third part of a special blog to mark the 10th anniversary of the ongoing Lumpur Sidoarjo mud volcano disaster. Part 1 examined the background and geology of the Lusi mud volcano. Part 2 examined the arguments for and against the proposed earthquake trigger model for Lusi, and concluded that there is very little evidence to support that hypothesis.
When I started this ‘Lusi trilogy’, I envisaged the third part would look at all aspects of the ‘drilling trigger’ model, and the evidence for and against this hypothesis. However, this part of the story quickly grew and grew to an ‘epic’ length. Furthermore, I got side-tracked from finishing this post by a long series of events that included being made redundant (boo!), falling ill (boo again!), starting a new business (yay - insert Rocky theme music here!), having my two PhD students submit back-to-back (awesome effort guys – but reading and editing 13 thesis chapters in 3 weeks was a big ask!) and seemingly half the journal editors on the planet swamping me with a pile of really interesting manuscripts to peer review (seriously, how did all you all know I was unemployed?). So, I have decided to ‘Harry Potter’ this final Lusi Blog part and break it into two sections, both because of the length this is becoming and also the horrible delays I’ve had in writing this blog.
The first section of this epic finale to the Lusi triggering story will set the scene. Drilling accidents don’t happen because of one event. Their root cause is always a number of decisions and events that may start weeks or months prior to the disaster, but which ultimately culminate in things going suddenly and spectacularly wrong. It is no different with Lusi. In this blog post, I will go through the many key aspects of drilling the Banjar Panji-1 well, in the months and weeks prior to the disaster, that resulted in the borehole being in a precarious condition. Whilst my next and final Lusi blog section will carefully dissect the key 48 hours leading up to the disaster, and the 3 days after the Lusi mudflow started.  This blog section herein is necessary because it will highlight the key incidents and decisions that, ultimately, meant that the major kick, when it happened, could not be controlled.
Note also that more details on mud volcanos and Lusi can be found by looking back on my twitter feed from May 2016 (@MarkTingay, #lumpurlapindo).

Introduction and Background

The Lusi mud volcano suddenly appeared and erupted in a rice paddy on the morning of the 29th of May 2006. Less than 150 meters away, the TMMJ-04 rig was drilling the Banjar Panji-1 (BJP-1) gas exploration well, which had been experiencing significant well control problems over the previous 2 days, including suffering a major kick that erupted over 360 barrels (>15000 gallons) of mud and water at the wellhead less than 24 hours earlier. The drillers on BJP-1 immediately assumed that the adjacent mud eruption was caused by the well control issues that started the previous day, and made several attempts to kill the Lusi mud flow, as well as calling in experts from a major well control company. However, just 2 days later, the operator of the BJP-1 well, Lapindo Brantas, decided to abandon the well, and started the ~36 hour process of closing the well and pulling the rig off location. Within a week, one of the partners in the well, Medco, had instigated legal proceedings against Lapindo Brantas for gross negligence in the drilling campaign, and the Indonesian government and police had also commenced investigations into the rapidly unfolding disaster.

From my examination of media reports and early technical reports, there seems to be little doubt that Lapindo Brantas felt initially (for several weeks, up to perhaps two months) responsible for the disaster, including agreeing to cover costs associated with initial damages. Yet, sometime during the following months, Lapindo started making claims that the Lusi mud volcano was entirely unrelated to the BJP-1 well, and was instead the result of entirely natural processes triggered by the Yogyakarta earthquake 274 km away (see Part 2 of this blog). Perhaps it is entirely coincidental that these new claims of innocence came around the time that Lusi became spectacularly larger, more violent and vastly more destructive in August 2006, not to mention being indirectly responsible for the deaths of 13 people (mostly police) in a pipeline explosion in November 2006, and the significant political connections of a senior Indonesian politician to Lapindo (or maybe I am just being cynical).
The debate about Lusi triggering in the wider scientific realm began with the publishing of the first major peer-reviewed paper on the disaster in early 2007 entitled “Birth of a mud volcano: East Java, 29 May 2006”, authored by a group of UK mud volcano and petroleum geology experts lead by Professor Richard Davies (Davies et al., 2007). In this key first paper, the limited data available at the time was compiled and analysed, and the authors concluded that the disaster was most likely the result of a blowout in the Banjar Panji-1 well. More drilling data started becoming available throughout 2007, and, it must be said, Lapindo Brantas were quite willing to share some data (which is exemplary and very unusual after a potential oil industry accident). This new data resulted in the first two major papers purely examining the triggering of Lusi (looking at both the drilling and earthquake trigger hypotheses) being published in EPSL and Geology in 2008 (Davies et al., 2008; Tingay et al., 2008). 2008 also marked the first (and only) international ‘great debate’ on Lusi triggering, which was hosted by the American Association of Petroleum Geologists at their International Conference and Exhibition in Cape Town (if you want to read more about this, I recommend this excellent Blog post by Chris Rowan, a fantastic blogger who actively wrote updates about the Lusi disaster for several years). Finally, in 2009 and 2010, there was another series of papers examining the drilling-trigger hypothesis. The first was written by Lapindo Brantas drilling engineers and geologists responsible for the well, and was their arguments for why drilling did not trigger Lusi (Sawolo et al., 2009). This paper is very important, as it provided a lot of the raw drilling data in a public and peer-reviewed source (previously, data had been made available to examine, but not necessarily to use). The Sawolo et al. paper was challenged on many fronts by Davies et al. in 2010, and countered with a reply by Sawolo et al. (2010) (though, it is worth noting that this reply did not actually address any criticism of Davies et al., and instead just repeated the claims of the 2009 paper). Yet, I have to say that, looking back now with a few years more experience and more detailed examination of available data, we (Davies et al., 2010) were too quick to write our reply. We missed a number of key things, and, in particular, failed to spot how so many of the claims made by Sawolo et al. (2009) are completely contradicted by Lapindo’s own reports and data that were buried in a digital appendix to the paper.

In this post, and Part 3B to follow, I aim to provide a summary of all the different claims surrounding the drilling-trigger hypothesis for Lusi. However, I will apologise in advance that this can be a difficult and tortuous subject! The deeper you go ‘down the rabbit hole’, the more you realise just how often statements and claims are frequently made without evidence (or in contradiction to evidence), how often key events seem to be ignored, how data may be erroneous or be potentially manipulated and, in particular, how some data can have two wildly different interpretations. In the drilling of BJP-1, there seems to be debate and uncertainty over just about every single little bit of data or events – and this makes it a very difficult subject to explore! Furthermore, the potential legal implications of this disaster necessitate being very careful to cross-check and carefully explain all the evidence.
Herein, I have tried to make it clear whether, and what, evidence is used to make claims and statements, and to highlight the contradictions when they occur. Please note that, herein, I have used the following assumptions when assessing the reliability of data and reported events.

1.       Evidence and data is stronger if it is supported in multiple places.

2.       Reports of events/data collected ‘on the day’ are considered more reliable than those made years later (once the extent of the disaster was seen).

3.       Interpretations based on normal, widely accepted and peer-reviewed practices are more reliable than those using non-standard or non-peer-reviewed methods.

4.       Interpretations done in accordance with standard drilling practices (e.g. seen in well control handbooks), and those taught by formal qualification providers (e.g. the International Well Control Foundation), are more considered more reliable and favoured over alternative approaches.


The Drilling Triggering Model for Lusi


In Part 2 of this blog I highlighted that both the earthquake and drilling-trigger models for the Lusi eruption are actually far more similar than most people realise. Both models suggest that ‘something’ caused a reduction in effective stress (stress minus pore fluid pressure) at the Lusi location, which, in turn, caused a fault or fracture to initiate/reactivate and allow overpressured water (containing clays) to escape to the surface. However, under the drilling-trigger model, the drop in effective stress is argued to be due to the increase in fluid pressure that occurred during a major drilling kick in the BJP-1 well. More precisely, the increase in fluid pressure occurred when the drillers closed the Blowout Preventer (BOP) at the surface of the well during the kick, which caused fluid pressures in the well to spike as pressures equilibrated. The drilling-trigger model is, in essence, an uncontrolled version of hydraulic fracture stimulation (fracking), in which the fluid pressure in a well is increased to such a high level that it fractures the surrounding rock formations.
Original Drilling Trigger model by Davies et al., 2007. Note the model assumes tensile fracturing during the BJP-1 kick, with kick fluids coming from the deep carbonates (please note that there are some geological errors in this figure - the 'sandstone aquifer' is actually tight volcanics and volcanoclastics, and the carbonates are not Kujung FM (which are actually Oligiocene), but are rather Miocene age and likely of the Tuban FM).

Another common aspect of all drilling-trigger models for Lusi is that the primary initial source of erupted water for Lusi is considered to be the deep Miocene carbonates, believed to be located at the final depth of the BJP-1 well (~2833m). In all drilling-trigger models, the highly overpressured carbonates form both the primary water source and driving force for the Lusi eruption, with fluids initially flowing up the BJP-1 borehole from the carbonates, before passing into a fault or fracture somewhere inside the Kalibeng clays, at which point the water mixes with the clays to become mud before flowing up to the surface to erupt at Lusi. However, despite the main commonalities, there are some slight variations between the drilling-trigger models by different authors, as well as some evolution of the models over time (as has been seen in the earthquake-triggering model in part 2).
Probably the biggest evolution or difference in the drilling-triggering models is that the original models (and most models up until ~2010) proposed that Lusi fluids escaped from the BJP-1 borehole to the surface via a purely tensile (mode 1) fracture. These models were actually based on the occurrence of similar blowout-triggered eruptions offshore Brunei in the 1970s that I had studied during my PhD (Tingay et al., 2003). The idea of tensile fracturing is significant, as it had been a well-established industry practice to assume that wells will likely fail in tension in well-control events, and many debates about whether or not kick pressures in Lusi were sufficient to cause fracturing were based on this assumption. However, since ~2010, I, and some other researchers, have suggested that the high kick pressures in BJP-1 were more likely to induce shear failure (mode 2 fracturing), and, thus, either initiate or reactivate a fault, rather than create a simple tensile crack.
Updated model for drilling triggering of Lusi, proposing that the increased borehole pressures during the BJP-1 kick were sufficient to induce shear failure (from Tingay, 2010).

There are several arguments to support the idea that the kick triggered shear failure rather than tensile failure. First, shear failure is more favourable given that fracturing appeared to initially be along an ~050°N oriented structure, which is optimally oriented for shear failure in the existing present-day approximately strike-slip stress-state and ~020°N maximum horizontal stress orientation (whereas tensile failure should occur sub-parallel to the present-day maximum horizontal stress; Tingay et al., 2010). Second, the present-day stress state is actually far more conducive to initiating shear failure than it is for tensile. As will be discussed in Part 3B, basic geomechanical models indicate that shear failure requires significantly smaller increase in borehole fluid pressure than is needed for tensile failure. Indeed, an interesting aspect of later Lusi drilling-trigger models involving shear failure is that they are even more similar to the earthquake-triggering model, which also assumes shear failure. Again, it should be reiterated that there really are, in essence, very little difference between then drilling and earthquake trigger models – they really only differ about ‘what’ caused the drop in effective stress that initiated/reactivated a fault, and on the initial source of water for the Lusi eruption (deep Miocene carbonates for the drilling-trigger, Kalibeng clays for the quake trigger).

Have Blowouts Ever Caused Mud Volcanoes?

One of the most common arguments against a drilling-trigger for Lusi is the misbelief that things such as mud volcanoes cannot possibly be human-triggered. It is remarkably common to hear statements along the lines of ‘Lusi is a mud volcano, and mud volcanoes are natural features, therefore Lusi must be natural’, or ‘drilling has never triggered a mud volcano’. Yet, these statements are both false and illogical. Indeed, they are similar to the erroneous logic discussed in Part 2, where people have argued that Lusi must be triggered by an earthquake simply because other mud volcanoes have been triggered by earthquakes. However, as discussed in Part 2, prior natural causes for events do not preclude current human causes for the same events. Classic examples are anthropogenic climate change, as well as human-induced seismicity (sure, climate change and earthquakes happen naturally, but this does not mean they can’t also be induced by human activity).

So, have mud volcanoes been triggered previously by drilling accidents? The answer is yes – many times! Indeed, I have found at least three other examples in Indonesia alone, such as the Dieng-24 blowout in Central Java, the Gresik mud volcano (near Lusi) in 2008 and a recent mud eruption triggered by geothermal drilling in Sulawesi. Furthermore, if we consider Lusi to be simply be the escape of high pressure underground water (the water just mixes with clay en route to the surface to become mud), then there are numerous global examples of major water blowouts from wells. As mentioned above, the initial drilling-trigger models for Lusi were based on a similar, albeit smaller, series of blowouts in the Champion Field, offshore Brunei. In 1974, and again in 1979, wells being drilled in the giant Champion Field encountered unexpected highly overpressured compartments and suffered major kicks. In both cases, the blowout preventer (BOP) at the surface held, and prevented major fluid eruption at the rig site. However, the fluids flowing into the wellbore, rather than escaping to the surface, instead started flowing into a shallow normally pressured compartment, in what is known as an underground (or internal) blowout. Gradually, the flow of deep pressured water into the shallow compartment increased the pressure in the shallow compartment (think of connecting an inflated balloon to a deflated balloon via a straw – air will flow from the high pressure to low pressure until both balloons reach pressure equilibrium).  After a few days, the pressures in the shallow compartment got so high that the overlying cap rock fractured, and allowed fluid to flow to the surface (termed a surface blowout resulting from an underground blowout). In both Champion blowouts, the fluids erupted in many places along a linear zones (like in Lusi), with some eruptions up to 5 km from the responsible well. In the Champion Field, they were able to quickly use other wells, and drill more wells, to contain the pressures underground and stop the surface eruption – but the underground blowouts actually continued for about 20 years!

Dieng Field mud eruptions triggered by drilling activity in Central Java, Indonesia.
Shallow seismic time-slice (essentially horizontal) of induced fractures and associated lines of eruption points generated by the Champion Field 1974 and 1979 blowouts (Tingay et al., 2003). This is just one of many examples highlighting how blowouts can also cause aligned eruption vents, as was seen in the first few days of the Lusi mud volcano.

There have been many other similar industry accidents, such as the Unocal Platform-A blowouts offshore Santa Barbara (USA), Chevron’s Frade blowout offshore Brazil and other events in Brunei and Azerbaijan. Hence, it cannot be said that similar events to Lusi have not ever been triggered by drilling. Furthermore, these other examples dispel another common argument that is still routinely made by Lapindo Brantas, and in papers authored by Dr Adriano Mazzini, which can be paraphrased as ‘Lusi cannot be due to drilling, because the mud flow did not erupt at the well, but rather ~150m away’ and ‘Lusi must be natural, because eruptions initially occurred in several places along a linear zone’ (Sawolo et al., 2009; Mazzini et al., 2009). For now, let’s just ignore the fact that >360 barrels of watery mud did erupt at the BJP-1 wellsite during the kick (before the BOP was closed), and note that there are numerous examples of wellbore blowouts causing eruptions at a distance from the well (up to 5 km distant), and that blowouts have also caused eruptions along extensive linear zones. So, these arguments against the drilling-trigger model are invalid. However, it must also be stated that, just like for the earthquake-triggering hypothesis, prior examples of drilling-induced eruptions cannot be used as direct evidence to support the drilling-trigger model for Lusi, and rather these can only be used to provide precedence that such events can potentially occur.


The Banjar Panji-1 Well

The Banjar Panji-1 (BJP-1) gas exploration well was targeting a Miocene carbonate reefal mound that was originally believed to be at ~2600m depth. This reefal build-up is the western-most of a series of five similarly aged reefal mounds that occur along a ENE-WSW line (Kusumastuti et al., 2002). All four other mounds had been previously drilled by the BD-1, KE-11E, KE-11C and Porong-1 wells (stated in east to west order), which had discovered either small (non-commercial) amounts of oil and gas, or only residual hydrocarbon accumulations. It was noted by several operators that the overburden near the crests of these reefal mounds tended to be highly faulted, which led to the belief that all four of these previously drilled structures were breached traps. Indeed, some gas fields are hosted in shallow Pucangan formation reservoirs within just a few kilometres of Lusi, such as the Wunut and Tangulangin Fields, and it is widely believed that the gas in these field migrated out of the breached Porong structure. Interestingly, the Porong structure, 7 km from Lusi, was even previously noted to be overlain by a large ‘circular collapse structure’ that, in hindsight, is probably caused by an earlier version of Lusi. However, whilst the crests of other mounds were highly faulted, it was noted that the Banjar Panji reefal structure did not appear to have nearly as much, or as intense, faulting in the overburden. Hence, the play concept for Banjar Panji-1 was quite simple – it was believed that the structure was an un-breached version of the nearby Porong, Kedeco and BD structures, and thus would hopefully hold commercial oil and gas accumulations (Istadi et al., 2009). It can perhaps be considered a cold comfort that the structure did not seem to contain large hydrocarbon volumes, or else Lusi could have been a far worse environmental disaster!

The Porong structure, drilled by the well Porong-1, located 7 km from BJP-1 and Lusi. Porong is the adjacent Miocene reefal high to the structure targeted by BJP-1, and porong-1 and BJP-1 are essentially sister wells. However, the structure targeted by BJP-1 does not have intensive faulting overlying it's crest. BJP-1 was thus testing the hypothesis that the neighbouring, and relatively unfaulted, structure would hopefully trap hydrocarbons. Porong was found to be breached, and it is believed that the hydrocarbons from Porong migrated into the Pucangan and are today being produced from the Wunut and Tangglangin Fields. What is also fascinating about Porong is the 'circular collapse' feature that, in hindsight, now indicates that the Porong structure is a earlier version of Lusi and has undergone caldera collapse during it's mud eruption.

In summary, BJP-1 was targeting what was hoped to be an un-breached version of the Porong reefal build-up, just 7km away, and the BJP-1 well was essentially a sister well to the Porong-1 well. The Porong-1 well was drilled by a different operator, but was in acreage taken over by Lapindo, and all Porong-1 data was available, and used, in the planning of BJP-1. I want to stress this point – as many definitive moments in the drilling of the BJP-1 well, and many of the (strange) drilling actions taken, all seem to directly contravene the data, observations and drilling experiences from the Porong-1 well. Furthermore, some actions made by Lapindo are nonsensically explained away as the drillers assuming that BJP-1 has the same conditions seen in offset wells >100km or more away, in geologically different fields in the offshore East Java Basin, rather than using the data and knowledge from the neighbouring sister well, Porong-1.
The BJP-1 well was spudded on the 8th of March 2006 by the TMMJ-04 rig (as an aside, Lapindo Brantas and the company that owns the TMMJ drilling rig were both ultimately owned by Abrurizal Bakrie, one of Indonesia’s wealthiest people and the welfare minister at the time of the disaster). I have provided a summary of the key drilling events of the BJP-1 well herein. However, I will briefly summarize some key aspects herein as well.

26” hole section: The BJP-1 well began encountering overpressures at very shallow depths of just ~350m below the surface, which led to the 20” casing being set ~13m shallower than planned.
17.5” hole section: Increasing overpressure, combined with high amounts of background gas and some wellbore instability (pack-offs) in the 17.5” hole section resulted in the 16” liner being set at ~666m depth, which was ~310m shallower than planned. Numerous indications that the 16” liner was not well cemented, including gas bubbling up from annulus, top squeeze cement job and need for bottom squeeze cement job after 16” liner shoe leak-off test (LOT).
14.5” hole section: Drilled to 775m with few problems (minor reaming). Pumps broke and took 16 days to repair. Drilled down to 1096m, with numerous connection gases and flows in the Upper Kalibeng clays, as well as wellbore instability issues. Further instability issues, flows and possible ballooning when reaming hole after wireline logging. Final 13-3/8” casing set at 1091m, 280m shallower than planned. Losses prior to cement job, and then during cement job, with some ballooning back – 756bbls lost during cement job. Indications of marginal cement job, including unusual LOT profile (discussed in detail later).
12.25” hole section: numerous connection gases and high overpressure indicators in the Kalibeng clays. Encountered unexpected thick volcanics/volcaniclastics, which greatly reduced drilling speed to just a few meters per hour. Drilled to 2667m, which is past the planned 11-3/4” liner point (1992m) and 9-5/8” casing point (2650m). Ran logs and check-shot survey. Decided to keep drilling until carbonates were reached. Experienced total losses at final well total depth of 2833m. Pulled back while pumping LCM slug. Losses temporarily stopped, but then continued during pull out of hole. Well kicked during pull out of hole, BOP shut-in, pressure spiked, followed by 24 hours of well control before the Lusi mud volcano appeared. Two days of well control occurred, including three attempts to stop Lusi by pumping high density mud down hole. Lusi mud eruption noticeably decreased during all three kill attempts, and then increased rate after kill attempts stopped (though Lapindo claim there was no evidence of connection between BJP-1 and Lusi mud flow during these tests). Decision made to cut string, place cement plugs and abandon well.



Did BJP-1 have Sufficient Casing?

Casing is a critical part of safe drilling practice. Casing is steel pipe that is placed in the well and cemented into place in order to seal off the upper sections of drilled rock formation, and to protect the rock from damage, such as due to the invasion of drilling mud into aquifers and losses due to fracturing. In particular, casing is used to maintain a safe ‘mud weight window’ while drilling. In order to drill a well safely, the density (‘weight’) of drilling mud must be kept within a range (‘window’) such that pressure in all uncased sections of the wellbore is greater than the maximum pore pressure and lower than the minimum formation fracture pressure (and also above the collapse pressure’ required to keep the well stable, but let us leave this out for sake of simplicity). The minimum safe ‘window’ for mud weight varies, but in all wells it is required that there be some safety tolerance between the maximum pore pressure gradient in an uncased section and the minimum fracture pressure gradient (usually assumed to be the leak-off test value at the casing shoe). Casing is set when the drilling mud weight window approaches a critically narrow range. The drilled hole section can be strengthened and protected by placing steel pipe along the open hole section, and then filling the annular space between the outside of the pipe and the wellbore wall with cement – preventing the cased section from being fractured (or overpressured fluids from entering any cased-off formation) and thus widening the mud weight window and allowing the well to be deepened safety.



Casing is so critical to well design that it is planned out and carefully designed long in advance of drilling the well. A basic tenant of drilling wells is to carefully plan the well and then stick to the plan. Indeed, any significant changes need to be documented in great detail and fully and carefully justified (usually via a detailed memo of the change with a full risk assessment). Yet, this was not done in BJP-1. The well was planned to have 6 strings of casing or liner set along the well (Tingay et al., 2008), with a casing shoe approximately every 610m (2000’). Yet, as described above, unexpected high pore pressures, losses (fracturing) and wellbore instability caused the 20”, 16” and 13-3/8” casing shoes to be set shallower, with the final 13-3/8” casing shoe set 280m shallower than planned (Sawolo et al., 2009). However, the real deviation from the drilling plan came with the repeated decisions to delay, or abandon, setting the 11-3/4” and 9-5/8” casing strings.


BJP-1 was planned to have an 11-3/4” liner set at ~2000m depth, which was prognosed to be inside the Kalibeng clays. However, the well instead encountered an unexpected layer of thick volcanics and volcaniclastics from ~1850m depth. It is not certain why the 11-3/4” liner was abandoned. The encountering of an entirely unprognosed geological unit would have been a valid reason to set casing. However, it has also been stated by Lapindo that this liner was just a contingency casing point. But, again, there is no reason given in any of the drilling reports as to why the liner was skipped. It is likely that it was not considered as needed, given that pore pressure gradients appeared to have plateaued, and the deeper rock was exceptionally strong, and maybe considered unlikely to fracture. Furthermore, it may have been a simple cost saving measure, as the well was already well behind schedule at this stage, following the earlier drilling issues and the 16 days downtime due to pumps, and was getting even further behind schedule due to the extremely slow ROP in the volcanics. Regardless of the reasons, which remain unknown and speculative only, the 11-3/4” liner was never set in place, and the decision was made to continue drilling to the 9-5/8” casing point.
BJP-1 was planned to have a 9-5/8” casing set at approximately 2630m depth, which was the predicted depth of the carbonate target reservoir. However, the depth to this reservoir was underestimated, due to the presence of the unprognosed volcanic layer that, with its extremely high velocity, resulted in erroneous depth conversion of seismic data. When the planned casing depth was reached and slightly exceeded, the decision was instead made to stop and run petrophysical logs and conduct a Vertical Seismic Profile (VSP), to try and estimate the depth to the top of the carbonates. The VSP results were inconclusive, and suggested carbonates could be as deep as ~2926m. The decision was made to not set casing yet, but to instead drill until the carbonates were reached, or until a maximum depth of 2865m (though no mention of this is made in the daily drilling reports – the only source is Sawolo et al., 2009). Ultimately, the well would reach a final depth of ~2833m and the 9-5/8” casing would never be set. This meant that the BJP-1 well had 1740m of open (uncased) wellbore when the well control issues commenced at the end of May 2006.

Did BJP-1 have sufficient ‘Drilling Window’?: Pore pressure and fracture gradient in BJP-1

Pore Pressures in BJP-1
Last year, I published a detailed compilation of pore pressure, fracture gradient and petrophysical data for Banjar Panji-1 and some surrounding wells (Tingay, 2015). Note that I am happy to provide this data to others that wish to examine the disaster. High pore pressures (overpressures) are commonly observed throughout the region, and commenced at shallow depths of only 350m (1150’) in BJP-1. Pore pressure gradients reached very high magnitudes of 17.2 MPa/km (14.6 ppg; 0.76 psi/ft) at just ~1200m (3900’) depth. Comparison of pressure data with newly updated geological information shows that overpressures under the Lusi mud volcano occur in three distinct formations: (1) shales of the Pleistocene Pucangan and Upper Kalibeng formations (~350-1870m depth); (2) Pliocene to early Pleistocene volcanic and volcaniclastic sequences (from 1870- ~2830m depth), and; (3) Middle Miocene reefal carbonates (>~2830m depth).

Pore pressure, leak-off test and overburden gradient data for BJP-1 and nearby offset wells in the Porong and Wunut fields (from Tingay, 2015).

The overpressures at BJP-1 start remarkably shallow, and reach very high levels at shallow depths, which further highlights the difficulties faced in drilling the BJP-1 well. Furthermore, whilst the overpressures in the Kalibeng clays are ‘textbook’ examples of standard disequilibrium compaction overpressure, it is highly unusual to see high magnitude overpressures in volcanics and carbonate rocks. Indeed, there are not even any well-established or reliable ways to predict pore pressure in these rocks, which makes well planning and drilling even more difficult.

Fracture Gradient in BJP-1
The fracture gradient in BJP-1 is reasonably well defined by the leak-off tests in BJP-1 and surrounding wells, although it should be stressed that, again, fracture gradients are notoriously difficult to predict or estimate in volcanics and carbonate sequences. However, one of the most controversial and debated aspects of the drilling of BJP-1 comes from the interpreted leak-off pressure from the final 13-3/8” casing shoe leak-off test. This is both because the interpretations of this test vary greatly in the literature, but also because it is this value that is often seen as defining the minimum pressure required during the kick to create the Lusi drilling-trigger scenario.

Leak-off tests are a standard test done immediately prior to drilling a new hole section, and are conducted for safety reasons to determine the maximum pressure the well can tolerate in a kick (and thus the pressure the borehole must be safely kept below). Leak-off tests are performed by first drilling out the recently cemented casing shoe, drilling a few meters into new formation, closing the annular BOP and then pumping drilling mud into the sealed well until the pressure increases enough to fracture the rocks. Pressures during a leak-off test should first increase in a linear fashion, as more drilling mud is forced at a constant rate into the fixed volume of the wellbore. The ‘leak-off pressure’ is generally interpreted as the point in which there is a break in slope of the increasing wellbore pressure, which is considered to represent the initiation of a small and growing fracture in the rocks at the bottom of the well, and thus a slight increase hole volume.
The debate over the interpreted leak-off pressure in BJP-1 stems from two things: the pressure gauge used and the point at which leak-off is interpreted. The most controversial part of Lapindo’s interpreted leak-off pressure is that they chose to use the absolute maximum possible value. First, Lapindo picked ‘leak-off’ as the maximum pressure value reached during the LOT, and not the first break in slope of the pressure increase. They cite an unavailable Unocal internal report as their rationale for this, even though this interpretation is contrary to every single interpretation methodology I can find in the literature (there are literally dozens of textbooks and papers that agree with this). This deviation from all known drilling practice, in my opinion, overestimates the leak-off pressure gradient by 0.6 MPa/km (or 0.5 ppg).

Available data for the BJP-1 leak-off test conducted at the 13-3/8" casing shoe at 1091m depth. Note that three pressure data curves are available, from three different gauges. Lapindo drilling reports state that they used the data from the 'Drill Pipe - Rig Floor Gauge' to derive a 15.7 ppg leak-off test. However, this was later modified to a 16.4 ppg LOT using the 'Halliburton gauge' data. In both instance, the leak-off pressure is taken as the maximum pressure reached during the test at approximately 6 barrels pumped. This is significantly higher than using the standard 'first-break in slope' approach, where leak-off is considered to occur after approximately 2 barrels pumped (data curtesy Lapindo and Sawolo et al., 2009).

The data from the leak-off test was collected on three gauges – a Halliburton drill pipe pressure gauge, a second drill pipe pressure gauge (unspecified) and a casing pressure gauge (also unspecified). It is not known where each gauge was located, and it is possible that the ‘Halliburton gauge’ is on the cementing unit, which may then be appropriate to use, but this is uncertain (sadly, it is also unknown how the test was lined up and executed on the day). Hence, it remains difficult to establish which gauge is most likely the more reliable. What is known is that Lapindo originally used the non-specific drill pipe pressure gauge data and then, several days later, modified their interpretation by using the Halliburton gauge. The use of the Halliburton gauge data (which showed higher pressures than all other gauges), combined with picking leak-off as the maximum pressure reached (and not the break in slope pressure), yielded Lapindo the maximum possible leak-off pressure value out of a wide range of possible interpretations.
There are several reasons why this is a dubious practice. First, I polled a number of geomechanics and drilling experts who argued that it is often the casing pressure that is more reliable during leak-off tests, rather than the drill pipe pressure. Second, and more importantly, the leak-off pressure represents a critical safety threshold that should never be crossed in a well control situation – and as such, it is common practice to ‘err on the side of caution’ and select the lower range of possible interpretations (and then place an additional safety margin on top), rather than to select the absolute extreme high case. Hence, Lapindo argue for a leak-off pressure gradient at the 13-3/8” show of 19.2 MPa/km (16.4 ppg). However, is more correct to say that the leak-off pressure gradient is within a range from 17.9-19.2 MPa/km (15.3-16.4 ppg), which is equivalent to a 19.5-20.9 MPa (2829-3037 psi) pressure range at the casing shoe, and that safe well control should utilise the lower end of this range.

The uncertainty of the 13-3/8” leak-off test represents a microcosm of data unreliability in BJP-1. Normally, a leak-off test value is something about which there is little debate – there are standard practices for the performing and interpretation of these tests, and it is usually just a single value that gets reported. Yet, even this fairly simple and standard test results in a significant degree of uncertainty, and thus major scientific and legal ramifications. The same can, unfortunately, be said for just about every other facet of BJP-1. Almost every single aspect and event that occurred has a degree of uncertainty and unreliability, or variation in possible interpretation – all of which clouds the waters in trying to determine the cause of the Lusi disaster.


Implications of Not Setting Casing on the ‘Drilling Window’ in BJP-1

It remains uncertain as to why the 9-5/8” and 11-3/4” casing strings were not set at their planned depth. However, what is perfectly clear from all the drilling reports and Sawolo et al. (2009) is that the driller’s intention was to drill into the target carbonates prior to setting the 9-5/8” casing. This is stated clearly in the drilling reports, and is Lapindo’s often stated reason for continuing to deepen the well beyond the planned casing point (though no memorandum of change or risk assessment for deepening the casing point has ever been provided). Yet, this decision makes no sense at all – and if this was the plan, then it is this decision to drill into the carbonates before setting casing that likely represents the primary root cause of the disaster.

In Sawolo et al. (2009), it is stated that the drillers believed that the carbonates would contain very low pore pressures, and thus that it would be better to set casing just inside the carbonates (it is common to drill a little way into lower pressure reservoirs before setting casing). Sawolo et al. (2009) state that this idea of a low pressure carbonate reservoir was based on observations of the Kujung formation being commonly normally pressured in many offshore fields. Yet, as described in Part 1 of this blog, the carbonates targeted in BJP-1 are not the Kujung carbonates, and are actually a completely different age. Furthermore, these statements also indicate that Lapindo were basing their prognosis on wells located >100km away offshore, rather than on immediately nearby wells in their own acreage, and which were used to design the well (particularly Porong-1). This seems oddly contradictory, to say the least!
I have previously highlighted that the BJP-1 well was extremely similar to the Porong-1 well. Indeed, the entire reason for drilling the well was the hope that it would be an unbreached version of the Porong structure. Yet, the decision to drill into the carbonates before running casing is almost suicidal when one considers the pore pressures and drilling history of Porong-1. In Porong-1, the casing was set just a few meters before the top of the carbonate target reservoir. This is the usual standard practice when drilling into a reservoir thought to contain highly overpressured gas, as it generally gives you a wide drilling window, and only a short section of uncased formation that may need well control. Yet, even with this proper precaution, Porong-1 suffered significant problems drilling into the carbonates. The Porong-1 well experienced several days of continuous well control delays, with alternative large losses and kicks when the highly overpressured reservoirs were penetrated (Tingay, 2015). Direct wireline pressure tests confirmed the data from several kicks: namely that the carbonates were water wet (minor residual hydrocarbons only) and highly overpressured (~18.5 MPa/km; 15.7 ppg). The drilling of even this short, ~50m, hole section in Porong-1 was further complicated by the narrow drilling window (leak-off test of ~19.2 MPa/km; 16.3 ppg), and the presence of high permeability thief zones in the carbonates (Tingay, 2015). But, eventually, the well was brought under full control, and Porong-1 was drilled to its final depth ~40m inside the carbonates.

The lessons from Porong-1, as the perfect offset well for BJP-1, are quite clear – the carbonates in BJP-1 are expected to be highly overpressured. As such, casing should be set prior to drilling into the carbonates. Yet, this was clearly not the plan in BJP-1. Despite the pore pressure measured in Porong-1 carbonates, and the thinking that the BJP-1 structure may be unbreached, and thus possibly even more highly pressured (and containing gas), the drillers repeatedly state that they intended to penetrate the carbonates before setting casing. Even stranger, the drillers made no effort to raise the mud weight prior to drilling into the carbonates – and thus apparently planned on using 14.7 ppg mud to drill into a gas reservoir target that their best offset well indicated contained pore pressures of 15.7ppg or more!

In short, the BJP-1 well, in its final days, was being deliberately drilled:
·         into a likely highly overpressured (≥15.7 ppg) gas reservoir with 14.7 ppg drilling mud (an ~1.0 ppg mud weight underbalance);
·         with an open hole (uncased) section that was ~1740m long, despite the well being planned to have no more than ~600m open hole section, and;
·         into expected ~15.7 ppg pore fluid pressure gradients that were close to, and very possibly exceeded, the leak-off pressure at the 13-3/8” casing shoe (15.3-16.4 ppg).

This course of action really makes no sense to me – it absolutely boggles my mind. Such actions are either:
·        based on horribly incorrect assumptions (e.g. using offset wells >100km away, rather than  the nearest and most relevant offsets, which makes little sense given the evidence that  Porong-1 was used in the well planning, including fracture gradient prediction);
·         terribly negligent (not doing proper well planning as is usually required by law);
·         Suicidal (knowing the likely conditions the well would encounter, but doing it anyway), or;
·         all of the above!

No valid explanation seems to be given for why the 11-3/4” liner was not set as planned, nor has any detailed documentation for defending this decision ever been provided. The failure to set casing, and the planned drilling into the carbonates before setting casing, breaches numerous drilling safety standards. Furthermore, it is quite possible that the Lusi disaster could have been avoided had either the 11-3/4” or 9-5/8” casing been set as planned.

Concluding Summary

We have now reached a point the BJP-1 drilling story that is around the 26th of May 2006 – which is about 3 days before the Lusi mud eruption first began, two days before BJP-1 experienced its major kick, and the day before BJP-1 experienced total losses at TD, as well as the day before the Yogyaykarta earthquake. I hope readers can recognize the hazardour condition the BJP-1 well was in at this point. The lack of casing, and decision to drill underbalanced into rocks that have pore pressures close to (and possibly exceeding) the 13-3/8”leak-off pressure, is the drilling equivalent to driving at high speed along a dark mountain road, at night and with no headlights. At this point in the story, nothing bad has happened – for example, driving unsafely does not mean that an accident will definitely occur, nor does it automatically mean an accident is the dangerous driver’s fault. However, it does highlight that the scene has been set for a disaster to occur – and that normal safety conditions and procedures were not in place. In the next Lusi blog post, I will go through, in detail, the drilling events that I believe triggered the Lusi disaster, and the evidence from the well that supports (and the evidence that argues against) the drilling-trigger theory.


References

Davies, R. J., R. E. Swarbrick, R. J.  Evans, and M. Huuse, 2007, Birth of a mud volcano: East Java, 29 May 2006: GSA Today, 17, 4–9
Davies, R., M. Brumm, M. Manga, R. Rubiandini, R. Swarbrick, and M. Tingay, 2008, The east Java mud volcano (2006 to present): an earthquake or drilling trigger?: Earth and Planetary Science Letters, 272, 627-638.
Davies, R. J., M. Manga, M. Tingay, S. Lusianga, and R. Swarbrick, 2010, Discussion on: “The LUSI mud volcano controversy: Was it caused by drilling?”, N. Sawolo, E. Sutriono, B. P. Istadi and A. B. Darmoyo, authors: Marine and Petroleum Geology, 27, 1651-1657.
Istadi, B., G. Pramono, and P. Sumintadireja, 2009, Modeling study of growth and potential geohazard for LUSI mud volcano: East Java, Indonesia: Marine and Petroleum Geology, 26, 1724–1739.
Kusumastuti, A., P. van Rensbergen, and J. Warren, 2002, Seismic sequence analysis and reservoir potential of drowned Miocene carbonate platforms in the Madura Strait, East Java, Indonesia: AAPG Bulletin, 86, 213-232.
Mazzini, A., A. Nermoen, M. Krotkiewski, Y. Podladchikov, S. Planke, and H. Svensen, 2009, Strike-slip faulting as a trigger mechanism for overpressure release through piercement structures. Implications for the Lusi mud volcano, Indonesia: Marine and Petroleum Geology, 26, 1751-1765.
Sawolo, N., E. Sutriono, B. P. Istadi, and A. B. Darmoyo, 2009, The LUSI mud volcano triggering controversy: Was it caused by drilling?: Marine and Petroleum Geology, 26, 1766-1784.
Sawolo, N., E. Sutriono, B. P. Istadi, and A. B. Darmoyo, 2010, Reply on “Discussion of: The LUSI mud volcano controversy: Was it caused by drilling?”, Davies, R. J., M. Manga, M. Tingay, S. Lusianga, and R. Swarbrick, authors: Marine and Petroleum Geology, 27.
Tingay, M., Hillis, R., Morley, C., Swarbrick, R. & Okpere, E., 2003. Pore pressure/stress coupling in Brunei Darussalam – implications for shale injection. In: Van Rensbergen, P., Hillis, R.R., Maltman, A.J. & Morley, C.K. (eds.) Subsurface Sediment Mobilization. Geological Society of London Special Publication, London, 216, 369-379.
Tingay, M., O. Heidbach, R. Davies, and R. E. Swarbrick, 2008, Triggering of the Lusi mud eruption: earthquake versus drilling initiation: Geology, 36, 639-642.
Tingay, M., 2010, Anatomy of the ‘Lusi’ mud eruption, East Java: Australian Society of Exploration Geophysicists 21st International Conference and Exhibition, 1-6, doi:10.1071/ASEG2010ab241.
Tingay, M., 2015, Initial pore pressures under the Lusi mud volcano, Indonesia: Interpretation, 3(1), SE33–SE49, doi:10.1190/INT-2014-0092.1.