Magnum Hunter's Farley Well Blowout
Are there any experts out there who can talk about this event?
Wickipedia describes a blowout as;
A blowout is the uncontrolled release of crude oil and/or natural gas from an oil well or gas well after pressure control systems have failed
Gary Evans in public statements said it took four days to bring the well under control, and said:
"We’re seeing a geo-pressured regime here like we’ve never seen before. So our first well, the Farley well actually blew out on us in a natural fracture, we didn’t frac the well. So we’re pretty excited about what we’re seeing. We had totally changed our drilling techniques in this region using South Louisiana Gulf Coast technology with high pressure, well heads, 10,000 pounds well heads, double BOPs."
It sounds like a serious, rare event.
#1 question: What does this indicate about the prospects for the well?
(Does this event indicate a terrific amount of pressure and a massive amount of gas to be uncorked? Or, does it indicate a screwup on MH's part? Or, did the "challenging geology" contribute to the blowout as he alluded to in an earlier statement)?
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Replies to This Discussion
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Permalink Reply by Steven A Joliat on
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I have no specific information on the conditions at the Farley well, but I'll take a stab at this. It seems that they clearly encountered higher bottomhole pressures than they had expected. The term blowout covers a wide range of conditions that can usually be described as the return of fluid from the borehole to the surface without the assistance of the mud pumps that normally circulate the drilling fluid in a well. It can range from a slow lifting of the column of drilling mud and sometimes progress to a rapid violent expulsion of liquid, gases and the drill pipe from the borehole with occasionally catastrophic results. The more violent the upflow, the more damage to the well and surface equipment that can occur if the well is not brought back under control. It seems that so far they have not reported abandoning the original bore, so they may have successfully gained control of the well without much surface damage or damage to the reservoir. This can often be the case. What it suggests about the future of the well is not so clear at this point. Best case is they have controllable high pressures in the reservoir that will yield large quantities of gas or oil from the formation. Alternatively, there may have been a large fracture system that has now depressurized and will now yield little gas. A fracture stimulation treatment may yet provide good steady production from the well, or not. Modern seismic data, which may or may not have existed for this well, often provides advance information about potential high pressure zones ahead of drilling, but this is not foolproof. Someone may have made errors that contributed to the well problems, or sometimes the "challenging geology," surprises the most experienced crews. Though I must say, "challenging geology," is often a euphemism for "failed to think this one through." MH may have screwed up, or it could simply be one of the unexpected events that occur in the early stages of drilling out a new play.
Time and the inevitable tendency of crews to talk while off the rig, will let us know what really happened at the Farley well. When the well reports to the state in several months, there should also be some useful public information. For now, I hope no one was injured in the initial incident, and the overflow was contained on site. I would expect the state well inspectors have been informed and at some point will file an incident report as well.
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Permalink Reply by The Hiker on
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Steven: Thanks for the expertise. It is an interesting bit of news, with limited information/analysis out there. It seems that MH only installed "gulf coast" technology after the blowout, which may indicate a screwup, as I've heard rumors that Antero encountered high pressure conditions early in their Point Pleasant drilling, and resorted to high pressure technology and "gulf coast" personnel to control it. I thought these guys talked to each other, but maybe not?
A related question: Do these drillers target fractures as a way of accessing large amounts of trapped gas "for free", or are fractures a really bad thing, as this incident may indicate? It would seem that trying to pressurize the bore during stimulation would be impossible if there was a large crack to "fill".
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Permalink Reply by Steven A Joliat on
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Screwup can be a valid assumption at times, but with everyone trying to get an edge in the play at this stage, the communication is not as likely as it may seem. There is also a history in the industry of the "not invented here syndrome." There are other historic cases in the area of high pressures in very old wells, but as MH is not a local, they may not have given much weight to anecdotes, if they were even aware of them. It is difficult to say why they proceeded as they did, without knowing the persons involved in the well planning.
Hard to say how large the fracture widths would be in their natural state without more data. I've never worked with a frac job on a naturally fractured reservoir, but I believe there are approaches that allow well stimulation to proceed. Natural fracture systems can be very enticing targets, as they can provide a fair amount of production for little effort.They can also turn into very challenging wells due to drilling problems, as seems to be the case here and with some of the Whitacre wells in Monroe County.
As far as evidence of the fracture system on regional seismic data, a lot depends on what exactly was gathered and how it was processed. If MH is not spending much on a seismic program for their own reasons and depending on the size and distribution of the fractures, I can see how they could be missed. I would hesitate to call it a competence issue at this point. Many times in my career I have heard the phrase, "we are not doing a science project here." Sometimes the extra effort pays dividends, sometimes not. I will admit it is difficult to make that call in advance.
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Permalink Reply by Sam Moore on
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3 times in the past 2 weeks there has been some very strange sound coming from the HG 702 site. The only way I can describe it is that whistling sound you hear in the old war movies right before the guy yells incoming and everyone jumps into the fox hole. Could this be gas being released from the hole?
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Permalink Reply by Brian Powers on
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Mr. Hiker -
An experienced drilling team with access to the rig's recorded drilling parameters and a chance to interview the crew on duty at the time of the incident could get to the bottom of this one quickly.
With automation, the parameters are recorded in discreet time steps and include such items as mud pump rate/pressure, RPM of the pipe (either rotary table or top drive), trip tank volume, mud pit volume, height of the blocks above the rig floor, etc. Consider this data to be analogous to the "black box" technology on a plane; its analysis is very useful in reconstructing events.
Interviewing the crew would answer important questions such as: was the crew trained to recognize and properly respond to well control events?, Did they ever perform well control drills?, was the rig equipment well maintained and in good shape?, was the mud in good shape and was the "weight up schedule" being adhered to? Who recognized what and when, and what was the first response and why?
In my experience and with my last companies' policy, every person involved in the design, preparation and execution of well operations had to be properly trained and certified in well control procedures, from the greenest new engineer in the office to the most grizzled, grey bearded and crusty company man on location. The same goes for the leadership on the rig contractor team. The certifications are achieved by examination and simulator time and are good for two years before having to be renewed.
Many companies also conduct well control drills periodically to ensure that the crews properly recognize and react to a potential well control event.
Drillers are taught early on to always keep the hole full of fluid and to minimize abrupt movements of the pipe to avoid surging or swabbing a well and introducing losses or taking an influx of gas, which migrates up hole due to density differences and expands, which can lead to underground blowouts or failure of surface equipment. The upsizing of BOP pressure rating suggests that a gas influx was anticipated. Double BOP's may allow for additional rams to seal pipe near surface, but otherwise would do nothing to mitigate risks.
Natural fractures large and small are not always a bad thing; the drilling and fluids programs have to be designed accordingly to accommodate them
Without knowing any more about the specifics, the initial query suggests to me that this was a preventable event, as most well control events are found to be (after they occur).
Brian
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Permalink Reply by ShaleRocks on
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Brian,
With the increased pressures in this area, will the actual fracing process be as effective as it is in lower pressure areas?
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SR-
Fracing in a naturally fractured reservoir is likely more challenging than in non fractured rock. Fracing requires two distinct down hole pressure events, the first is to initiate the frac and the second is to extend and hold the frac open while the proppant laden fluid is forced into it. The presence of natural fracs suggests to me that the first challenge has been overcome' but treating rock in these environments often results in massive fluid leak off that causes loss of hydraulic force required to hold the frac open. The leak off can be controlled to a certain extent by additives and surface pump pressure, but not always.
Downhole rock mechanic properties govern frac initiation and propagation more than reservoir pressure does, in my view, but if pressure is a controlling factor, heavier base frac fluid or more proppant per gallon of fluid added might be required, bearing in mind the surface pressure limitations of the frac pumping spread.
Brian
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Permalink Reply by Francine Booker on
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screwup on MH's part - the natural fracture should have been noticed if they did adequate seismic testing and competent analysis prior to drilling.
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Francine-
All of the seismic lines that I've looked at in naturally fractured reservoirs show mainly the large, bounding faults and their orientations. I cannot recall once seeing the presence of natural fractures on seismic, data obtained while drilling confirms this; the orientation can be inferred by the gross seismic picture.
Brian
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Permalink Reply by Craig Cooper on
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Francine,
I don't believe the blowout necessarily indicates a screwup on MH's part.
As Brian says, fracture systems are very difficult, if not impossible, to detect on conventional seismic data (aka P-wave seismic data). Fracture systems can be detected & imaged on shear wave seismic data (aka S-wave or sometimes converted-wave / C-wave seismic data) however acquisition & processing of shear-wave seismic data is more expensive and a bit more challenging so is not often acquired. I reckon MH had good quality conventional 3D seismic but not shear-wave seismic data.
Regardless, it is the (unexpected) presence of high / over pressure that is the fundamental issue rather than the presence of natural fractures. As Brian et al have already said, gross pressure regimes can be identified via conventional 3D seismic and is often calculated IF there is some expectation that abnormal pressures exist. I don't recall seeing any mention of the presence of abnormal pressures elsewhere in the area so suspect that the additional calculation wasn't performed prior to the drilling of the well. I also suspect that MH will add pressure prediction to their pre-drill checklist for future wells :-)
Though there are a few reasons why high / over pressure may occur, in the 'shale' plays its regional presence may be a good thing. In the Bakken, parts of the Eagleford & the Haynesville, for example, the higher pressures generally indicate that the hydrocarbon 'kitchen' is active & working (i.e. generating). In addition, the presence of over pressure often enables higher IPs and, in some cases, EURs.
So, it will be important to monitor other future wells as they are drilled to determine whether this blowout was due to an isolated pressure cell or whether it is indicative of a more active regional 'kitchen'.
Frac'ing can be performed in the presence of natural fracture systems as well as (regional) over pressure; e.g. Bakken, Eagleford. It is important to be aware of the presence of ('open') natural fracture systems since these can act as super highways for fluids; both to & from the well bore. In general, they can be identified pretty effectively during drilling via LWD tools (i.e. logging while drilling).
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Craig -
It's nice to see a fellow O&G professional weigh in on these posts. I studied geophysics briefly in university and then with my first employer (Amoco).
I used to love hanging out with the geophysicists, they were all generally irreverent, all had biting senses of humor, and they had the coolest computers, software and displays in the building - way better toys than we engineers had.
I agree with your opinion that most companies now use their mud loggers to collect real time pore pressure prediction data to help validate and calibrate their mud weight up programs/schedules and to help avoid surprises and unwanted/unwarranted attention.
Thanks again for your seismic insights.
Brian
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