Accumulation conditions for continental shale oil and gas in the Biyang Depression

Abstract

The AS1 Well in the continental shale reservoir in Biyang Depression reached a peak production of oil 4.68 m~3/d and gas 90 m~3/d after hydraulic fracturing stimulation,marking a major breakthrough in shale oil gas exploration and development in the Eogene continental faulted basins in eastern China.Oil in shale is often symbiotic with gas.The data gathered from geological experiments,well logging,etc.,are used to analyze shale distribution,organic geochemical features,reservoir characteristics and sealing conditions of AS1.Results show that major shale layers within the interval of 2450 -2510 m in well AS1 feature in great thickness and wide distribution of a single layer,high TOC and a R_o within 0.57%-0.72%,indicating that the source rocks are maturity and in peak hydrocarbon generation.R_o Gas logging of shale oil gas layers show abnormal results and the logging curve present special features of 3 high points and 2 low points.Shale layers contain well-developed micro-pores and fissures,which can be excellent reservoir space.The layers are also rich in brittle minerals like quarts,which is favorable for fracturing.After assessment by using the volumetric method,we believe that the Depression has great shale oil and gas exploration potential(about 0.54 billion tons of shale oil gas).