Oil and gas exploration breakthroughs and insights in the western segment of Silurian Shajingzi structural belt in Tarim Basin

The exploration degree of Silurian oil and gas in the northwestern part of Tarim Basin was relatively low. The oil and gas discovery was obtained in the eastern segment of Shajingzi structural belt from wells XSD 1 and XSC 1 from 2019 to 2021, and then the industrial gas flow was also achieved in XSD 2 well, which extended westward in 2023. Based on the analysis of drilling, oil testing, geochemical, geological characteristics in Shajingzi area and the results of field profile measurements, and combined with the targeted processing and detailed interpretation of 2D seismic data, the authors in this paper conducted an analysis of the reservoir formation model and evaluation of resource potential. The results are as follows. ① Large sand bodies were developed in Silurian Kepingtage Formation in Shajingzi structural belt, with favorable reservoir-seal assemblages. The wells XSD 2 in the eastern segment, XSC 1 and XSD 1 in the western segment, have all achieved industrial gas flow, revealing the oil and gas potential of Silurian strata; ② Shajingzi fault system is large in scale and long in duration, connecting the high-quality source rocks in the deep part of Awati depression. This fault system also controls the formation of a series of structural traps and structural-lithology traps in Shajingzi structural belt. The reservoir formation period is mainly Himalayan period after the traps were formed, characterized by “fault-dominated, late-stage reservoir formation”; ③ Forty-two traps have been identified in Silurian Kepingtage Formation of Shajingzi structural belt, with a predicted trap resource volume of 198.21 million tons oil equivalent, indicating significant oil and gas exploration potential. The results of the study could provide some references and basis for the next step in the evaluation of the exploration area.