Atoka’s approach to surface geochemistry is from a different perspective than others. The use of surface geochemistry is over a century old and it is a tool that, at present, is best used in reconnaissance processes in areas where there is sparse or no drilling. Surface geochemistry is at its best in areas where reservoirs are stacked, single pay, or where pay zones do not overlap but will work in most plays and reservoirs at depths of 10,000 feet or less.
Some of our competitors sell the concept that surface geochemistry will help find sweet spots in shale or coal resource plays. Historically, many of these resource plays were present when the industry was looking in the same areas for conventional targets. However, these unconventional reservoirs typically do not cause definable anomalies at the surface. When coalbed methane resources are present and producing, Atoka has seen no relationship between CBM resources and surface geochemical anomalies at the surface. Methane gas is retained within the coal matrix or fractures by water and, in most coalbed methane plays, gas is not produced until at least a year or more of dewatering. Methane, by itself, is typically discarded in surface geochemical analysis because its source can be not only from hydrocarbons at many depths but also from oxidation of soil and plant and microbial activity around the surface. Analyzing methane sources is a sophisticated and lengthy process that generally doesn’t amount to a significant increase in gas production. Shale oil and gas plays typically require horizontal drilling and extensive fracturing of rock that has little to no productive permeability. There are exceptions to this, but compared to conventional targets, the leakage from these traps is generally minimal to nonexistent.
Indicating the presence or absence of micro-seepage from depth, as related to conventional reservoirs, is the key to surface geochemistry. The absence of any surface anomalies typically implies no hydrocarbon accumulations present. Thus, there is a high likelihood that drilling will result in a dry hole. Having anomalies present in the reservoir can have many implications, anything from a minor accumulation of hydrocarbons that is not economic, to an economic and productive reservoir.
Unless it is not possible, a surface geochemical survey should be supported by geology and 2D or 3D seismic. In some areas, surface geochemistry has been able to be used to locate drill sites. Historically, the successful results of this type of approach have diminished over time as the accumulations of hydrocarbons being sought get smaller and smaller. Some of our competitors suggest using surface geochemistry to define fault systems in unconventional plays which by itself is fine. In most unconventional plays operators avoid these tectonic features as they typically represent areas of high water production or areas where the reservoir(s) have been breached. Fault systems are more accurately defined by seismic.
Surface geochemistry is a great tool in exploration for any conventional project you may have.
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