Fine evaluation and favorable area prediction of deep source rocks in northern Songliao Basin

¹ Exploration and Development Research Institute of Daqing Oilfield Co.，Ltd., 163712 Daqing Heilongjiang, China
² Key Laboratory of tight oil and shale oil accumulation of Heilongjiang province, 163712 Daqing Heilongjiang, China

^* Corresponding author: zhangfan1@Petrochina.com.cn

Abstract

Focusing on Xujiaweizi fault depression, the geological conditions and geochemical characteristics of deep natural gas formation in the north of Songliao basin are evaluated, the natural gas resources are estimated, and the favorable areas are optimized. Shahezi Formation shale is a set of coal bearing sediments with high organic matter abundance (TOC is 1%～12%), high over maturity (Ro is 1%～4%) and shore shallow lake facies, which are mainly distributed in Xujiaweizi fault depression, Gulong-Lindian fault depression and Yingshan fault depression. The thickness, TOC, R_o and hydrocarbon generation of four thirdorder sequences with different lithology (mudstone and coal) are carefully evaluated for the Shahezi Formation shale in the deep layer of Songbei. The comprehensive evaluation shows that the mudstone thickness of Es4 member in Anda and Xuzhong areas of Xujiaweizi fault depression is large (150 ~ 525m), TOC is high (1% ~ 4%), thermal evolution degree is high (R_o is 1.2% ~ 3.4%), and gas generation intensity is high (20 ~ 815) × 108m³ / t), moderate buried depth (3000~4500m) and overlapping area of 756km². It is a favorable exploration area for natural gas and shale gas in Daqing Oilfield.