地质科技通报 (Jul 2022)
Key factors of far-source hydrocarbon enrichment in the northern uplift area of Enping Sag in Pearl River Mouth Basin
Abstract
Petroleum exploration in the Enping Sag of the Pearl River Mouth Basin began in the 1970s, however, no commercial oil and gas discovery has been achieved through 40 years of exploration. In recent years, successive significant breakthroughs of hydrocarbon exploration have made the northern Enping Sag become a hotspot of exploration. By analysing the Neogene petroleum entrapment characteristics in the uplift area of the northern Enping Sag, the key factors of the far-source accumulation mode are summarized in this region.Firstly, the long-term active boundary fault system deep inside the sag is the key factor for the large-scale northwards migration of oil-gas in the northern Enping belt. This kind of fault controlled the provenances of the Wenchang Formation in the steep slope belt at the early stage and cut through the storage sandbodies and source rock of the Wenchang Formation in inherited activities of the late stage so that the oil and gas generated from the source rock of the Wenchang Formation could be adjusted vertically to the middle-shallow strata through the oil source faults. Secondly, after the lateral migration across the fault plane, oil and gas can gather along the structural ridge of the hanging wall of the fault and continue to migrate northwards for a long distance and enrich. The coupling of oil source faults, storage sandbodies and structural ridges is the key factor in far-source oil and gas enrichment in the northern uplift of the Enping Sag, which implies the great exploration potential of deep storage sandbodies in the Wenchang Formation.Therefore, the uplift area in the northern Enping sag has the conditions of far-source enrichment of oil and gas, and there are still many structural traps in the north of the breakthrough area, which will be a potential zone for Neogene oil and gas exploration.
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