ENRICHMENT CHARACTERISTICS AND RESOURCE POTENTIAL OF SHALE OIL IN THE FIRST MEMBER OF QINGSHANKOU FORMATION IN SOUTHERN SONGLIAO BASIN

There is a set of high quality semi-deep to deep lacustrine dark shale developed in the first member of Qingshankou Formation(K₂qn¹) in Changling Sag, southern Songliao Basin, with large sedimentary thickness and stable distribution. A lot of residual hydrocarbon exists in shale layers with shale oil resource potential. Based on massive data of well logging, oil testing, core sampling and experimental test, the paper comprehensively analyzes the main controlling factors of enrichment including content and distribution of residual hydrocarbon, lithofacies assemblages, reservoir space and mineral compositions in the shale. The results show the residual hydrocarbon is mainly medium-light oil, with good fluidity and enrichment range of 1800-2500 m vertically. The shale of K₂qn¹ can be divided into bedded, laminated and interbedded lithofacies types, and the content of residual hydrocarbon in the former two types is high, with TOC more than 1.5% generally, Type Ⅰ and Type Ⅱ₁ of organic matters, pyrolysis S₁ more than 2×10^-3, porosity more than 5.5%, mesoporous-macroporous pore size, brittle mineral content more than 50% and good fracturing property, which is the major enrichment pattern of shale oil. Through superposition of main controlling factors of enrichment and evaluation of favorable lithofacies, JYY-1HF well is optimized and deployed in Qian'an enrichment area and 16.4 m³/d of shale oil flow is yielded after fracturing. The shale oil resource of K₂qn¹ in Changling Sag is estimated to be 35×10⁸ t by pyrolysis S₁ method, proving that the southern Songliao Basin has considerable shale oil resource potential.