The French term, déjà vu, which means literally “already seen,” is the feeling that you have previously experienced something you are currently experiencing. Two thirds of adults claim to have sensed this phenomenon, but this figure rises to 100% when one considers professionals in the oil and gas industry, which is undergoing yet another boom-and-bust cycle.
Besides the real concern that the recently announced staff layoffs will only hasten the “big crew change” (as some “golden oldies” may decide to call it a day this time around), one hopes that operators will maintain good stewardship of their wells and fields and resist the temptation to cut back on essential data acquisition.
Reservoir stewardship, in which operators accept the responsibility to shepherd and safeguard the assets of a company or a country, involves the periodic review of asset performance to ensure productivity and recovery targets are met and maintained, and to guide future work plans. Continuous reservoir appraisal and surveillance are essential to minimize production losses from downtime in wells, facilities, and export systems. Unfortunately, it is evident that some operators (and governments) pay only lip service to good reservoir stewardship, especially when oil and gas prices are low.
Sometime ago, I read a student thesis that looked at options for reducing costs in the unconventional “factory drilling” process. It concluded that significant time and money could be saved if formation evaluation services were eliminated from the well program. The project sponsor was happy with the result and the student graduated, but I was appalled that this suggestion could ever be taken seriously. Unconventional reservoirs have complex pore systems, very low interparticle permeability, contain free and adsorbed gas, and exhibit variable water salinity, all of which make their characterization a major challenge for the geoscientist.
Therefore, more core data (not less) are needed to calibrate the responses of logging suites, which also require enhanced measurement services as opposed to standard tool strings. The taking of core permits subsequent rock typing to include dynamic properties and fracturability and allows partitioning of the reservoir into zones that reflect quartz content and producibility.
Conventional reservoir evaluation also comes under threat in a low oil price environment. The major cost overruns in wells are invariably due to drilling failures, not data acquisition. Yet on being told to cut costs, the usual reaction of well engineers is to challenge the need for coring and logging in the formation evaluation program. We are constantly faced with the dilemma of short-term benefit vs. long-term worth when acquiring data. However, the latter tends to be more subjective and is therefore harder to quantify in “value of information” terms, which leads to myopic operators gathering only data required for the decisions in hand.
At the field level, daily accurate measurement of produced fluid volumes and surface pressures and regular records of reservoir pressure are vital for sound reservoir management. Without these data, history matching is impossible and uncalibrated simulation models can lead to suboptimal investment decisions and poorer resource estimates. Operators must regard adequate data acquisition as essential, rather than as an unnecessary overhead, otherwise the stewardship of their assets will be impaired.
It seems incongruous that operators would rather defer or even cancel the acquisition of data from their producing assets, and instead use assumptions, estimates, and analogs (assuming the latter are available and analogous) to populate their reservoir models. These dynamic models, which take many months to build and run, can therefore never be optimized, yet their outputs are used as the basis for future reservoir management decisions.
For example, some operators of offshore developments declare their preference for running bottomhole pressure surveys and production logs in some wells each year, rather than installing permanent downhole gauges. My experience suggests that few of these surveys are subsequently carried out, which means that the actual reservoir pressure and zonal flow contribution, essential for validating any dynamic model, can go unchecked year after year.
Production efficiency is a global problem, and one that is particularly severe in the UK North Sea, where fields exhibit average annual production losses of almost 40%. Of course, operators are wary of publishing such data, yet this metric is at the heart of the asset stewardship strategy in the UK government’s UKCS: Maximising Recovery Review: Final Report by Ian Wood. This independent study proposes that operators must be held to account “to ensure […] the proper stewardship of their assets and infrastructure consistent with their obligations to maximize economic recovery from the fields under their licenses and with consideration to adjacent resources.”
A Production Efficiency Task Force of North Sea operators, contractors, and UK government officials was set up in 2014 to tackle this issue and hopes to set a common basis of measurement of production efficiency, with an underlying choke model, this year. Success will depend on the willingness of companies to share best operational practices to help increase economic recovery and to allow benchmarking of comparable field performance by regulators.
In the 1993 movie “Groundhog Day,” Bill Murray, who is reliving the same day over and over, asks a restaurant owner, “Do you ever have déjà vu, Mrs. Lancaster?” She replies, “I don’t think so, but I could check with the kitchen.” Experienced professionals do not need to check with the kitchen, but they do hope that the industry has learned from past mistakes made in the name of cost reduction.
Bob Harrison, SPE, is a consultant petroleum engineer who worked for more than 20 years with British Gas and Enterprise Oil, and currently advises on international project delivery for LR Senergy. Harrison’s major interest is rapid, accurate screening of oil and gas assets. Harrison has edited textbooks on formation evaluation and has published more than 35 technical papers. He serves on the SPE London Section Board and is a Technical Editor for SPE Reservoir Evaluation & Engineering. In 2014, he received the SPE North Sea Region Award for distinguished contribution to petroleum engineering in Management and Information. He holds a BS degree in electrical engineering from the University of Manchester, an MS degree in petroleum engineering from Imperial College, London, and an MBA degree from Cranfield University.