关键词: 富烃洼陷, 古近系, 古潜山, 新洼陷, 资源潜力, 珠江口盆地

Abstract: Pearl River Mouth Basin has still been in the stage of medium- and low-degree oil and gas exploration. In recent years, more efforts have been put on the research and evaluation of new fields in the basin and achieved a series of exploration results. We have realized new discoveries from multiple fields and types of exploration in hydrocarbon-rich depressions, i.e., the Paleogene of Wenchang A depression, Lufeng depression, Huizhou depression and Panyu 4 depression, the paleo-buried hill in Huizhou depression, as well as new depressions including Yangjiang East depression, and Kaiping depression. This has achieved large-scale reserves, thus reinforcing the reserve base for the stable development of oil fields in the east and west of South China Sea. It is clarified that the large-scale pressurization fault transitional slope zone in a fault basin indicates the main direction of exploration for large- and medium-sized oil and gas fields, thus changing the fact that no large scale reserves had been discovered in Wenchang A depression for many years. We innovatively proposed an understanding of hydrocarbon accumulation, i.e., "early fault transportation, small-scale source sink system and transformation zone controlling sand, and accumulations controlled by uplifts between depressions", guiding the discovery of the Paleogene high-yield oilfield group in the southern Lufeng sag. The establishment of exploration techniques for the fan delta-braided river delta sedimentary system has promoted the discovery of oilfield group on 10⁸t scale in the Palaeogene steep slope in the southwestern Huizhou depression. Deepening the research on reservoir-seal combination and petroleum entrapment in sand-rich series can contribute to the exploration and discovery of large- and medium-sized oil and gas fields in the new series of strata in Enping Formation of Panyu 4 depression. Innovatively establishing a model of diagenesis-mountain formation-reservoir formation-hydrocarbon accumulation for magmatic arcs in Mesozoic continental margins has guided the southwestern Huizhou depression to achieve a large-scale commercial breakthrough in the paleo-buried hills. The significant discovery of the oilfields group in East Yangjiang sag-North Enping sag is promoted by innovating the new mechanism of strong extension and weak strike slip controlling basin and hydrocarbons. Moreover, the innovative proposal of basin formation mechanism in the mode of "detachment-metamorphic core complex" is expected to form an oilfield group on a billion ton scale in the southern Kaiping belt. We have gradually developed new exploration fields such as Paleogene strata, buried hills, and new depressions and multiple technology series in Pearl River Mouth Basin, providing a solid technical support for the continuous increase of reserves and production in the eastern and western oilfields of South China Sea and opening up new prospects for new fields and new types of exploration. The resource evaluation results show that the remaining resources of the Paleogene system in hydrocarbon -rich depressions and buried hills in Pearl River Mouth Basin are mainly distributed in Huizhou 26 depression, Wenchang A depression, and etc. The crude oil resources are most abundant in the periphery of the Yangjiang-Yitong'ansha fault zone and the new depressions around Huizhou-Lufeng area.

Key words: hydrocarbon-rich depression, Paleogene, paleo-buried hill, new depression, resource potential, Pearl River Mouth Basin