Abstract:

There were many hydrocarbon plays with long geological time span in the western part of Pearl River Mouth Basin. The major plays were different from one structural zone to another. Starting from exploring reasons for the differences of hydrocarbon play distribution, we analyze characteristics, distribution patterns and main controlling factors of the upper, middle and lower plays in the Hanjiang Formation and Wenchang Formation in the western part of this basin. On the basis of above findings, we establish three poolforming patterns: 1) “longdistance lateral migration and accumulation in anticlines” for the Neogene Zhujiang Formation in the uplift; 2) “vertical migration and accumulation in secondary structure and lithologic reservoirs” for the Neogene Zhujiang Formation; 3) “vertical migration and accumulation in composite reservoirs” for the faulted slope belt in the sag. Three favorable plays are recognized: 1) lowamplitude anticline reservoir and relevant secondary lowresistivity reservoirs in the Qionghai uplift; 2) fault block reservoirs in the 2^nd member of the Zhujiang Formation of the faulted slope belt in the WenchangB sag; 3) subtle stratigraphiclithologic reservoirs in the northern slope of the WenchangB sag. The predictions are proved by drilling with the discovery of three commercial oilfields at the X structure in the downthrow wall of the south fault belt, the Y structure in the Qionghai uplift and the Z structure in the Qionghai uplift.