Hydrocarbon supplying characteristics of tight oil source rocks in Pingdiquan Formation, northeastern Junggar Basin

In the northeastern Junggar Basin, oils were self-generated and self-preserved in the Pingdiquan Formation. Because of tight reservoir and frequent sand-shale interbedding, the hydrocarbon supplying ability of source rocks is the key factor of tight oil exploration in the study area. The studies of organic matter abundance, type and maturity of source rocks from the Pingdiquan Formation showed that the source rocks from the first and second members of the Pingdiquan Formation are featured by high organic matter abundance and favorable organic matter type, and are during the low-mature and mature stages, hence have high ability of hydrocarbon supplying, but the vertical distribution of main hydrocarbon supplying sections varies among different regions. The hydrocarbon supplying centers in the first and second members of the Pingdiquan Formation have inheritance. There are three hydrocarbon supplying centers including the Huoshaoshan anticline-Huodong-Huonan area, the Shishugou Sag, and the Cai2-Dinan1 well area in the Wucaiwan Sag. Source rock evolution was affected by structure. The source rocks in the Huodong Syncline and Shi-shugou Sag are the most mature, and have reached hydrocarbon generation peak, while those in the Huonan Slope and Wucaiwan Sag take the second place, and are in the early mature stage. The source rocks in the Huoshaoshan Anticline, Huobei, Shadong and Zhangpenggou areas have the lowest maturity. The present exploration achievements have been made mainly in the Huoshaoshan Anticline, Huodong and Huonan areas, while the Shishugou Sag and the Cai2-Dinan1 well area in the Wucaiwan Sag also have good potential.