Hydrocarbon Exploitation in Mature Areas Using Geology and Technology, Usa Examples

Lee T. Billingsley
Abraxas Petroleum, San Antono, TX

Exploitation of natural resources usually follows an evolutionary process known as the resource pyramid. The most concentrated and easily extracted deposits are the first to be harvested. More mature stage deposits are less concentrated and more widely disseminated. The in-place volumes of these later, mature-stage deposits usually exceed that of the earlier stage. However, wide dissemination also causes higher recovery cost, and actual recovery volumes depend on higher product prices and/or improved technology. Like other natural resources, oil and gas also follow a pyramid-type of recovery process. The USA was endowed with abundant oil and natural gas resources, but today the USA contains some of the world’s most mature provinces. The USA provides a good example for mature stage extraction of oil and gas, and geoscientists play a crucial role in both identifying the deposits and supporting effective use of technology.

The East Newark field, Fort Worth basin, USA provides a model for the use of geoscience to effectively guide technology in mature stage development. The field’s unconventional reservoir, the Barnett Shale, was first discovered in 1981, but early development was slowed by poor recoveries. Geologic contributions to solving the economics for this unconventional reservoir include: structural setting, location of faults and fractures, distribution and thickness of highly organic facies, geologic and thermal history of the basin, and mineralogy for optimum fracture treatments. Currently the field has over 6000 completed wells, and most wells since 2003 are horizontal. With about 2 BCF per day in production, it is the second largest gas field in the USA.

Similarly, the Bakken Formation in the Williston basin, USA is a recent beneficiary of horizontal drilling and completion technology. The US Geological Survey estimates the Bakken play to contain several billion barrels of recoverable oil, and these estimates are a result of activity in the past five years.

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