Accumulation conditions and key exploration & development technologies of heavy oil in Huanxiling oilfield in Liaohe depression, Bohai Bay Basin

The Huanxiling oilfield is located in the southern part of the western slope of the western sag in Liaohe depression. The west side of this oilfield is connected with two sets of high-quality source rocks of Member 3 and Member 4 of Shahejie Formation in Qingshui sub-sag. The oilfield has fan delta, turbidite fan and other types of reservoirs, it also has cap rock of thick mudstone in Member 3 and Member 4 of Shahejie Formation. Under background of the warped basement, the warped fault-block draped compound trap zone are developed, which includes nine types of trap. From perspective of hydrocarbon accumulation, the slope of this area has always been the target area for hydrocarbon migration and accumulation. Inclusion analysis shows that there are multiple stages of hydrocarbon charging in this area, and the main reservoir forming period is the sedimentary period of Member 3 of Shahejie Formation and the sedimentary period of Dongying Formation. High-quality source-reservoir-cap conditions ensure large-scale hydrocarbon accumulation in this area. Based on the theory of compound hydrocarbon accumulation, many types of oil and gas reservoirs, including light oil reservoir and heavy oil reservoir, have been found in this area, with total reserves of 500 million tons. In view of the oilfield characterized by large reservoir burial span, multiple oil-bearing strata, strong heterogeneity and various types of oils, multi-batch seismic data processing & interpretation technology and thin reservoir inversion technology based on geological model are established in the preliminary exploration period, steam-flooding physical simulation technology of heavy oil, oil-reservoir fine description technology of thermal recovery heavy oil, steam huff and puff technology of ordinary heavy oil and steam-flooding technology of mid-deep buried heavy oil are developed in the development period, and technologies such as separate-layer injection, selective injection, sand control and lifting of heavy oil are matched and improved. These technology series provides technical guarantee for efficient exploration and development of Huanxiling oilfield.