Drilling practices: The good, the bad and the ugly
When an operation is carried out with due diligence and international best practices, the risk of operational failure is very slim. A case study will be analyzed this week for the benefit of operators who drive their drilling operations with the two-cardinal program of “CUT COST” and “MAKE PROFIT” only. This case study, THE GOOD opens DrillByte’s trilogy on drilling practices (The Good, the Bad and the Ugly). The GOOD shall remain a reference point in the industry for years to come. The other side of drilling below standards, whichever standard, THE BAD and THE UGLY comes with its own reward and will be subsequently discussed. They are the gas kick of Ibewa-1 onshore Nigeria and the Macondo blow-out in the Gulf of Mexico, the biggest oil spill in the history of mankind and the largest settlement in the history of drilling.
Oil companies are all developing methods of reducing cost of drilling operations. Companies, in some cases are therefore, left with the option of choosing which procedure to follow in the best interest of their business. That interest, oftentimes, does not give enough consideration to the safety of personnel nor ample time for the planning of the operation. We have the industry standard, a company’s standard and a country’s regulation though some countries do not even have any standard regulation!
An exploratory well is one in which there is little or no information about its drilling and geological history and sometimes, it is basically drilled to gather information. It is the driller’s nightmare, a challenge to the geologist and unattractive business to investors. A high pressure, high temperature, HPHT well, on its own, is enough to run away from by operators, drillers and geologists. When you now have to drill an exploratory HPHT well, it is left to the reader’s imagination how daunting such a task will seem.
An HPHT exploratory well has been previously drilled unsuccessfully by two operators including Elf Nigeria limited. They all ended in a fiasco! Enter ExxonMobil Corporation and Nkanda-1 HPHT exploratory well. The prospect was too attractive to be ignored and ExxonMobil needed to drill this well to get all needed information. For this to happen, they had to pull resources together with TotalFinaElf and other co-venturers.
The well was planned for close to two years. There was only one drilling rig in the world, at the time, for such a well and that rig was ENSCO-100. It was the rig ExxonMobil contracted. A senior instructor, Norman Archibald, with the International Association of Drilling Contractors, IADC was flown in from Houston to train all concerned personnel on well control methods. Concerned personnel were quartered in the prestigious Eko Hotel and Suites with training conducted in the nearby Protea Hotel. It was a hyper-normal drilling operation and the cream of the industry was assembled. There was a pore pressure analyst (Tina Fitts, PhD) based in ExxonMobil’s Houston office. She worked from there but was involved in the planning stages in Nigeria. There was another pore pressure analyst, a Nigerian based in the ExxonMobil’s Lagos office. Then, there was a site-based pore pressure analyst, another Nigerian who worked from the rig. Information between these three was conducted through real time data with decisions and instructions shot out in less than five minutes. A pore pressure analyst is someone with the expertise of predicting the pressure of the fluids within the fractures and pore spaces of rocks at any given depth interval. It is not a 100% foolproof solution but the error margin between the estimated and actual should not be more than 5% for a good program. ExxonMobil paid for the best in the industry and got the best. The drilling program was designed in such a manner that everybody directly or indirectly concerned with drilling operations had the right to raise the red flag, “STOP DRILLING”. ExxonMobil’s policy along this line was that, it is better to err on the side of caution than assume at the risk of danger. The error margin between the predicted and actual pore pressure estimates was within tolerable range which helped in managing the drilling operations all the way to the total depth, TD.
The well also had a mudlogging supervisor for the nine months it lasted, a well site geologist and regular crew of mudloggers. The idea behind having a mudlogging supervisor was to have someone with requisite experience sit on the mudloggers’ neck to get the very best out of them, which was subsequently handed over to the well site geologist for necessary action. The operator’s Houston and Lagos offices were open 24/7. Team work, like when a pride of Lions hunt down a Buffalo was crucial and therefore, religiously adhered to. The well was drilled to 15,240ft with a mud-weight of 18.50 pounds per gallon, and thereafter, plugged back and abandoned. It was a wonderful experience with zero incidents and accidents, the best of its kind anywhere in the world. Men and machine were successfully demobilized and Nkanda-1 became the first exploratory HPHT well safely, soundly and successfully drilled in Nigeria by ExxonMobil Corporation.
Finally, the drilling practices applied by some operators in Nigeria are below industry standards and for such operators and relevant oversight agencies, their reward is in the well! THE GOOD side has just been discussed. The bad and the ugly are sure to follow!
Kayoda Adeoye is an energy expert in Lagos