Characteristics and key exploration technologies for ultra-deep strike-slip fault-controlled condensate gas reservoirs： A case study of the No. 4 strike-slip fault zone in the Shunbei area， Tarim Basin

The ultra-deep， strike-slip fault-controlled condensate gas reservoirs in the Shunbei area of the Tarim Basin exhibit extremely strong heterogeneity， posing significant challenges to both the characterization precision for fractured-vuggy reservoirs and the advancement of exploration technologies. In this study， we investigate the characteristics of such reservoirs in the No. 4 strike-slip fault zone in the Shunbei area. The reservoir geological models are constructed for segments with pull-apart， compressive， translational， and oblique weak compression properties in the fault zone. Moreover， key exploration techniques are developed， focusing on three-dimensional quantitative characterization of fault-controlled fractured-vuggy reservoirs， along with optimal landing zone selection and trajectory design for high-yield wells. The results indicate that the ultra-deep， strike-slip fault-controlled reservoirs exhibit grid-like structures， corresponding to an integrated reservoir model with multiple grid-like structures. These reservoirs exhibit high hydrocarbon enrichment and production due to multiple factors： supply from the Cambrian source rocks， hydrocarbon transport along fault slopes， hydrocarbon enrichment governed by fault-controlled grid-like structures， multi-stage hydrocarbon charging， and dynamic hydrocarbon accumulation. The mechanisms underlying the differential hydrocarbon enrichment of the condensate gas reservoirs include early-stage oil charging， multi-episodic differential gas charging during the late stage， and weak secondary modifications. Two key exploration technologies are developed， that is， a three-dimensional quantitative characterization technology for fault-controlled fractured-vuggy reservoirs， which is centered on compressed sensing-based frequency expansion， phase-controlled wave impedance inversion， and three-dimensional analysis， and a spatial positioning technology for landing target zones based on three parameters： source rock-connecting major fault planes， strong beadlike wave troughs， and stress field direction. These technologies provide technical support for the landing zone selection and trajectory design of high-yield wells. The theoretical achievements and technology application in this study have enabled maximum productivity with a minimum number of wells in the No. 4 fault zone within the Shunbei area， providing a typical case for the exploration and exploitation of ultra-deep carbonate condensate gas reservoirs.