Using noble gas geochemistry to evaluate fluid migration in hydrocarbon bearing black shales

Abstract

American energy costs steadily increase leading to increased unconventional energy use. However, scientific barriers prevent widespread and economic development of these resources. In gas shale plays, resource utilization is limited by the understanding of how hydrocarbons and other fluids migrate in fractured rock. This limits industry's ability to extract hydrocarbons with enhanced recovery methods; prevents exploration in areas where hydrocarbons do not collect in traditional traps; and could unfortunately lead to dangerous environmental consequences such as contaminated groundwater. To address these concerns, the present invention integrates geochemical and geostructural techniques in a novel method for evaluating and optimizing the placement and drilling strategies of extraction wells in hydrocarbon rich black shales. By correctly choosing hydrocarbon “sweet spots” companies can reduce the number of unprofitable wells, choose directional drilling and completion strategies to accurately reflect the subsurface, and better select prime small- and full-field reservoirs.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of U.S. Provisional Application No. 61 / 413,967, 2010 Filed Nov. 15, 2010.FIELD[0002]The following description relates generally to natural gas recovery, and more particularly to a method for identifying highly productive locations for hydrocarbon extraction from black shale.BACKGROUND OF THE INVENTION[0003]Driven by geopolitical and hydrocarbon reserve uncertainties and the continuously increasing real cost of energy, domestic energy production is necessary to ensure the energy security and independence of the United States. In order to meet these increasing energy demands with domestic production, unconventional energy resources such as shale gas, shale oil and alternative coal technologies must be increasingly utilized. Economically viable production of unconventional energy resources requires enhanced methods of oil and gas recovery such as hydraulic fracturing and horizontal drilling.[0004]The combin...

AI Technical Summary

Benefits of technology

[0006]The following simplified summary is provided in order to provide a basic understanding of some aspects of the claimed subject matter. This summary is not an extensive overview, and is not intended to identify key/critical elements or to delineate the scope of the claimed subject matter. Its purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

[0007]Black shales are of great interest as domestic hydrocarbon plays because of their high organic content and tight gas-retaining nature. Although market demand is increasing interest in shale hydrocarbon extraction, the present inventor is unaware of any comprehensive methodology capable of identifying highly productive areas known as “sweet spots” because of a paucity of information about geological fracture-related fluid flow. Because of the immense costs associated with horizontal drilling and hydraulic fracturing, as wel

Problems solved by technology

The use of hydraulic fracturing is limited by: 1) inefficient resource recovery, 2) the potential for groundwater contamination from drilling fluids or mobilized hydrocarbons that can migrate through fractures and interact with groundwater, and 3) the current inability to develop accurate models for fracture fluid flow in the exceedingly complex fracture network present in black shale and other fractured lithologies.

Although market demand is increasing interest in shale hydrocarbon extraction, the present inventor is unaware of any comprehensive methodology capable of identifying highly productive areas known as “sweet spots” because of a paucity of information about geological fracture-related fluid flow.

Because of the immense costs associated with horizontal drilling and hydraulic fracturing, as well as the risk of environmental impact, hydrocarbon recovery from unconventional sources, such as black shale, is not economically favorable unless wells hit a sweet spot.

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