Pyrite is one of the important components of shale and plays a crucial role in shale gas enrichment.However,currently there are just a few studies on this subject matter.Therefore,the characteristics of pyrite in orga...Pyrite is one of the important components of shale and plays a crucial role in shale gas enrichment.However,currently there are just a few studies on this subject matter.Therefore,the characteristics of pyrite in organic-rich shale section of the Longmaxi Formation and its impact on shale gas enrichment was studied in this paper by using outcrops,drilling cores,thin sections and test data.Result shows that pyrite occurred in different forms(macro-micro scale)in the Longmaxi Formation in the southeast Sichuan Basin.The formation and content of pyrite has a close relation with TOC content.Pyrite may catalyze the hydrocarbon generation of organic matter.Interparticle pores within the pyrite framboids and organic matter pores in the pyrite-organic matter complex are welldeveloped in the Longmaxi Shale,which serves as a major reservoir space for shale gas.Pyrite can promote shale gas enrichment by absorbing shale gas on its surface and preserving free gas in the interparticle pores and organic matter pores.In addition,as a kind of brittle mineral,pyrite can improve the brittleness of shale reservoir and increase the micro-nano pore system in shale reservoir,thereby improving the transmission performance of shale reservoir and boosting shale gas recovery.展开更多
Determination of gas adsorption capacity under geological conditions is essential in evaluating shale gas resource potential.A quantitative determination of gas adsorption capacity was proposed through 1)investigating...Determination of gas adsorption capacity under geological conditions is essential in evaluating shale gas resource potential.A quantitative determination of gas adsorption capacity was proposed through 1)investigating controlling geological factors(including both internal ones and external ones)of gas adsorption capacity in organic-rich marine shale with geochemical analysis,XRD diffraction,field-emission scanning electron microscopy,and methane sorption isotherms;2)defining the relationship between gas adsorption capacity and single controlling factor;3)establishing a comprehensive determination model with the consideration of all these controlling factors.The primary controlling factors of the sorption capacity for the studied O3wLower S1l shale are TOC,illite and quartz,temperature,pressure,Ro,and moisture(water saturation).Specifically,TOC,thermal maturity,illite,and pressure are positively correlated with sorption capacity,whereas,quartz and temperature contribute negatively to the sorption capacity.We present the quantitative model along with application examples from the Wufeng-Lower Longmaxi Shale in the southeast Sichuan Basin,west China,to demonstrate the approach in shale gas evaluation.The result shows that the comprehensive determination model provides a good and unbiased estimate of gas adsorption capacities with a high correlation coefficient(0.96)and bell-shaped residues centered at zero.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.41602147,41702149,and 41728004)。
文摘Pyrite is one of the important components of shale and plays a crucial role in shale gas enrichment.However,currently there are just a few studies on this subject matter.Therefore,the characteristics of pyrite in organic-rich shale section of the Longmaxi Formation and its impact on shale gas enrichment was studied in this paper by using outcrops,drilling cores,thin sections and test data.Result shows that pyrite occurred in different forms(macro-micro scale)in the Longmaxi Formation in the southeast Sichuan Basin.The formation and content of pyrite has a close relation with TOC content.Pyrite may catalyze the hydrocarbon generation of organic matter.Interparticle pores within the pyrite framboids and organic matter pores in the pyrite-organic matter complex are welldeveloped in the Longmaxi Shale,which serves as a major reservoir space for shale gas.Pyrite can promote shale gas enrichment by absorbing shale gas on its surface and preserving free gas in the interparticle pores and organic matter pores.In addition,as a kind of brittle mineral,pyrite can improve the brittleness of shale reservoir and increase the micro-nano pore system in shale reservoir,thereby improving the transmission performance of shale reservoir and boosting shale gas recovery.
基金supported by the National Natural Science Foundation of China(Grant No.41972160)Open fund of Key Laboratory of oil and gas resources research,Chinese Academy of Sciences(KLOR2018-7).
文摘Determination of gas adsorption capacity under geological conditions is essential in evaluating shale gas resource potential.A quantitative determination of gas adsorption capacity was proposed through 1)investigating controlling geological factors(including both internal ones and external ones)of gas adsorption capacity in organic-rich marine shale with geochemical analysis,XRD diffraction,field-emission scanning electron microscopy,and methane sorption isotherms;2)defining the relationship between gas adsorption capacity and single controlling factor;3)establishing a comprehensive determination model with the consideration of all these controlling factors.The primary controlling factors of the sorption capacity for the studied O3wLower S1l shale are TOC,illite and quartz,temperature,pressure,Ro,and moisture(water saturation).Specifically,TOC,thermal maturity,illite,and pressure are positively correlated with sorption capacity,whereas,quartz and temperature contribute negatively to the sorption capacity.We present the quantitative model along with application examples from the Wufeng-Lower Longmaxi Shale in the southeast Sichuan Basin,west China,to demonstrate the approach in shale gas evaluation.The result shows that the comprehensive determination model provides a good and unbiased estimate of gas adsorption capacities with a high correlation coefficient(0.96)and bell-shaped residues centered at zero.
