Accumulation conditions and key technologies of exploration and development for Qingshimao gas field in Ordos Basin

Qmgshimao gas field was explored in 2022, which has the proved area of 2 151 km2 and proved reserves of 1 459 X 10sm3, making it the eighth gas field of hundred billion cubic meters in Changqing oilfield. By reviewing the exploration history of Qmgshimao gas field, the geological characteristics of natural gas accumulation are summarized as follows. The main gas-bearing stratum of Qmgshimao fas field is the Member 8 of the Permian Xiashihezi Formation; the main source rocks are coal seams and dark mudstones in Carboniferous Benxi Formation, Permian Taiyuan Formation and Shanxi Formation, characterized by widespread hydrocarbon generation. Delta front subfacies sedimentary system is developed, where the distributions of sand bodies are controlled by multiple provenances, multiple drainage systems, strong supply and multiple channel. The reservoir is dominated by fluvial channel sandstones with an average porosity of 7. 9% and an average permeability of 0. 363 mD, indicating a tight reservoir, and the connectivity of sand bodies is controlled by their distribution. The pressure coefficients of gas reservoir range from 0. 78 to 0. 90, demonstrating a low pressure gas reservoir. The reconstructed gas reservoir under the control of lithology and structure was formed due to long-term continuous charging under low hydrocarbon generation intensity, adjustment and transformation of tight reservoirs by fault systems, and high source-reservoir pressure difference. The three-dimensional seismic exploration, sand body fine characterization, and well location selection under complex gas-water relationships are key technologies for exploration and development of Qmgshimao gas field. © 2023 Science Press. All rights reserved.