Microgravity Monitoring Technology for Deep Gas-Reservoir Development based on DiXi 121 Wellblock in Xinjiang Oilfield

The difference in natural-gas enrichment significantly affects the underground medium density and thus the surface gravity. Microgravity monitoring technology monitors the morphological changes of a gas-reservoir development zone by measuring the surface gravity to obtain the change information of gas-reservoir development. The separation and extraction of gravity anomalies in microgravity monitoring is necessitated to accurately characterize the changes in gas-reservoir development intervals. The depth recursive method is the preferred method for separating residual gravity anomalies of different scales and extract reliable residual gravity anomalies. Considering the Dixi 121 well area of Xinjiang oilfield as an example and using the dynamic data of oil and gas drilling and production, the relationship between residual microgravity anomalies and reservoir characteristics is investigated in this study. Additionally, microgravity monitoring technology is applied to the development of gas reservoirs in middle and deep reservoirs, and a forward modeling of sand-ground ratio is performed based on the geological conditions of the study area. Subsequently, the response of sand thickness to the residual gravity anomaly field is analyzed. The results show that microgravity monitoring technology is effective for the development of middle and deep gas reservoirs. A larger sand-ground ratio corresponds to fewer residual microgravity anomalies, which is consistent with the forward modeling and sand-body distributions described using seismic data.