Paleogene geological framework and tectonic evolution of the central anticlinal zone in Lufeng 13 sag, Pearl River Mouth Basin

Significant breakthroughs have been achieved in the exploration of Paleogene reservoirs in the Lufeng Depression. However, as drilling depth is becoming greater, the discovered oil and gas reservoirs show signs of transition from conventional to unconventional accumulations, and the identification of conventional and unconventional reservoir boundaries is of particular significance. Herein, the hydrocarbon dynamic field boundaries in the Lufeng Depression are comprehensively identified by the geological drilling result method, the sandstone pore throat radius critical value discrimination method and the dry layer drilling rate variation method; then, the hydrocarbon dynamic field is divided and the characteristics and differences of hydrocarbon accumulations in each hydrocarbon dynamic field are compared. The results show that the buoyancy-driven hydrocarbon accumulation depth in the Lufeng Depression is between 3,500-4,000 m, and the hydrocarbon accumulation depth limit is about 5,800 m. The focus of research on Paleogene oil and gas exploration in the Lufeng Depression should be placed on conventional oil and gas reservoirs in the free dynamic field and tight oil reservoirs in the reformed dynamic field. As for the Enping Formation and Upper Wenchang Formation, efforts should concentrate on conventional oil and gas reservoir exploration, and the tight reservoir of Lower Wenchang Formation should be explored in the high fracture density area in C-4 and C-8 well blocks and the west of C-8 well block of the Lufeng 13 sag. The research results of this paper are of great value in further increasing oil and gas production and the explorarion of sreserves in the Lufeng Depression.

Section: Geological Settingmentioning

confidence: 98%

Section: Geological Settingmentioning

confidence: 99%

Hydrocarbon dynamic ﬁeld division and its relevance to oil and gas exploration for Paleogene reservoir in Lufeng Depression

Pang

Zhang

et al. 2022

“…NW-SE to north south (NS), the NE-ENE direction of fault activity gradually weakened, and the west northwest-east west (WNW-EW) direction became the dominant fault trend in the Enping Formation (Wang et al, 2019).…”

Section: Tectonic Evolutionmentioning

confidence: 99%

Controlling effect of tectonic-paleogeomorphology on deposition in the south of Lufeng sag, Pearl River Mouth Basin

Jiang

Chen

Chang

et al. 2022

Paleogene depositional systems in the south of Lufeng sag have complex spatial distribution, which are influenced by pre-depositional paleogeomorphology and multiperiod tectonic activities. In this paper, to clarify the controlling effect of tectonicpaleogeomorphology on sedimentary facies distribution and effectively guide oil and gas exploration, the Paleogene paleogeomorphic pattern in the south of Lufeng sag is reconstructed by the impression method, and the temporal and spatial evolution laws of the main faults are clarified. The results show that braided river deltas developed stably in the long-axis gentle slope belt of the lake basin, while the short-axis sedimentary system changed from fan deltas to braided river deltas in response to the change of active strength of dominant faults from strong to weak. It is found that the scale of the sedimentary fan is closely related to the activity of the main fault, the area of the catchment, and the vertical elevation difference. The steep cliff is controlled by the boundary fault with large fault throw and steep section, and there are wedge-shaped sand bodies near the steep cliff. The multi-level fault-step zone provides the driving force for the advancement of the sedimentary system, and the sand body extends for a long distance. It is established that the supply capacity of the source area and the accommodated space of the lake basin are coupled to control the deposition scale. Moreover, the slope controlled by the combination of paleogeomorphic assemblage and the activity of the main fault determines the sedimentary type, and the structural slope-break zone defines the spreading pattern of the sands.

“…1). The Cenozoic tectonic evolution of the Pearl River Mouth basin includes three stages: rifting, depression and rapid subsidence (Wang et al, 2019). The Wenchang Formation and Enping Formation were mainly deposited in the lacustrine rift stage during the Eocene.…”

Section: Location and Geological Settingmentioning

confidence: 99%

“…With the focus of oil and gas exploration gradually shifting to deeper layers, deeper oil and gas resources are also receiving more and more attention from oil workers (Athens and Caers, 2019). Deep geological exploration has high uncertainty and considerable exploration risk, and obtaining a reliable and simple method to determine the effective reservoir in deep strata is an important issue directly related to the exploration process (Mohaghegh 2014;Wang et al, 2019;He et al, 2020;Okunuwadje et al, 2020;Barach et al, 2021;Tang et al, 2022). The development and distribution of different types of high-quality reservoirs are controlled by the combination of tectonic, stratigraphic, petrographic, fluid and time factors, among which the evaluation of effective reservoirs is a popular issue in deep oil and gas exploration (Huang et al, 2020;Zeng et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Criteria and favorable distribution area prediction of Paleogene effective sandstone reservoirs in the Lufeng Sag, Pearl River Mouth Basin

Wang

Chen

et al. 2022

As the focus of conventional oil and gas exploration is changing from shallow to deep layers, the identification of deep effective reservoirs is crucial to exploration and development. In this paper, based on the geological anatomy of oil and gas reservoirs, a new discriminatory criterion and evaluation method for effective reservoirs is proposed in combination with the analysis of reservoir formation dynamics mechanism. The results show that the hydrocarbon properties of the reservoir vary with the ratio of the capillary force between the sandstone reservoir and its surrounding rock. The effective reservoir is discriminated and the reservoir quality is evaluated based on the capillary force and depth of the surrounding media and the sandstone reservoir for adjacent plates. When the capillary force ratio is greater than 0.6, fewer effective reservoirs are developed. The effective reservoir is determined by the capillary force ratio of the sandstone reservoir and the surrounding rock medium to mechanically explain the geological phenomenon that low-porosity reservoirs can also accumulate hydrocarbons. Our findings have significant guiding value for Paleogene oil and gas exploration in the Zhu I depression of Pearl River Mouth Basin.