Effective Source Rock Distribution Of Qingyiduan And Controls On Oil And Gas Reservoirs In Anda-Weixing Area

Anda-Weixing area is located in the northern part of Songliao basin,it has good petroleum geology condition. However, source rocks distribution in Anda-Weixing area did not identify, and there has found the hydrocarbon reservoirs at the Putaohua reserviur in the south of the study area, but northern has no significant oil and gas shows, the reason is not clear. So this paper is mainly to evaluate the K1qn1 source rock with geochemical method, and establish an effective source rock evaluation standards. Determine the effective distribution of source rocks. Analysis the expulsion characteristics of effective source rocks and its controlling effect on oil gas reservoir, to provide theoretical guidance for the next exploration.On the basis of the existing seismic data, geochemical data, well logging data and drilling data, evaluate the geochemical characteristics of hydrocarbon source rocks, and evaluate source rock of single well which is the standard well by use the ΔlogR method. Determine the fitting formula and use it on the other wells. And then determine the distribution range of source rocks by the limit of abundance of organic matter and hydrocarbon expulsion threshold. In the course of the study, the mainly achievements are as follows:(1)there mainly developed two effective source kitchen in the area of Anda-Weixing, they are the Anda effective source kitchen in the north of study area and the Shengpingbei effective source kitchen in the south of study area. Effective source kitchen in southern area of Putaohua reservoir is the main source kitchen.(2)The indicators of source rocks in the K1qn1 of Anda-Weixing have reached good- very good level, The quality of hydrocarbon source rock is generally good.(3)The source rocks in the K1qn1 of Anda-Weixing, the lower limit of organic matter abundance is TOC>2%, and the depth of hydrocarbon expulsion threshold is 1680 m, only in this way can source rocks occur expulsion and be migrated to the Putaohua reservoir forming a hydrocarbon reservoirs.(4) Shengpingbei effective source kitchen in the south of study area has a greater contribution to the reservoir of Putaohua, the mainly reasons for the difference of north and south hydrocarbon kitchen are as follows, the thickness in the Anda effective source kitchen is too thin, and it is leads to insufficient supply of hydrocarbon, although the source kitchen has reached the hydrocarbon expulsion threshold, the total hydrocarbon generating capacity has not reached the maximum value, insufficient hydrocarbon generation leads to insufficient supply of hydrocarbon, the K1qn1 of Anda effective source kitchen has abnormal high pressure, cause it has a large pressure gradient with the underlying K1q4, but transition smoothly with the overlying strata K1qn2+3, caused the oil and gas filling down priority, but in the Shengpingbei effective source kitchen, the oil and gas can filling everywhere and occurred lateral migration, resulted the Putaohua reservoir mainly distributed in there, and few found in the Anda effective source kitchen. The concentration of oil layer is controlled by the distance, the closer the distance from Shengpingbei effective source kitchen, the higher oil enrichment, and vice versa.