Abstract:
Tarim Basin has enriched oil and gas resources in ultra-deep marine carbonate rocks, where China's largest weathering crust-type oil reservoir and largest condensate gas reservoir have been discovered. However, the oil and gas exploration and development have been conducted only in palaeohighs and slopes for a long time. In recent years, with breakthroughs in the traditional theoretical understanding of "oil accumulation controlled by palaeohighs and enrichment in slopes" and advances in the supporting technologies of seismic exploration, drilling and development, Fuman oilfield, the ultra-deep (over 7 500 m) strike-slip fault-controlling oilfield, has been discovered in the depression area. Exploration and development practice and studies of the Fuman oilfield show the following results. First, the developed strike-slip faults not only cut through the deep Lower Cambrian source rocks, but also control the development of Middle Ordovician carbonate cavity-fracture reservoirs, and constitute a superior petroleum accumulation system under the control of strike-slip faults together with the huge thick Upper Ordovician mudstone. Second, the oil and gas show a stripe-shaped differential distribution along the strike-slip fractured zone, characterized by special trap type, large oil column height, good oil property, and high single-well production. Third, the predicted geological reserves of oil are up to 4×10
8t, the amount of oil resources is 10×10
8t, and there are many efficient development wells. The oil productivity of 160×10
4t/a has been rapidly achieved. Through continuous research, the supporting technologies such as ultra-deep, high-density and wide-azimuth 3D seismic acquisition, characterization of weak strike-slip faults, evaluation of traps in carbonate fractured zone, efficient well location deployment, ultra-deep drilling and completions have been gradually established in the desert area, providing supports for the large-scale and efficient exploration and development of the ultra-deep complex fault-controlling carbonate reservoirs.