Advanced LWD Logging Suites Help Develop Deep Low-Permeability Oil Reservoirs in the Eastern South China Sea

Abstract Oilfield A is the first deep fluvial clastic low-permeability oilfield in pearl river mouth basin to enter the development stage. The ODP design uses conventional LWD tools with directional wells to exploit the medium-porosity and low-permeability light oil reservoir with a thickness of about 140m. The production of directional wells in the early stage of development was much lower than that of the ODP design. How to evaluate the permeability of the formation and how to extract the formation crude oil became the key. Core data show that the low permeability characteristics of the formation are controlled by the grain size, the type and existence form of filling materials, and the complex pore structure characteristics determine the quality of the formation. It is difficult to evaluate the permeability of reservoir with complex pore structures using conventional logging data and single porosity parameters. LWD NMR, LWD Acoustics and LWD Ultra-sonic Image logging data characterize the reservoir quality from the perspectives of pore structure, formation anisotropy, fractures, etc. Under core calibration, the problem of evaluating formation permeability is solved. The development well type is transformed from directional well mode to horizontal well mode. LWD Extra-deep geo-steering tools can provide electrical characteristics of relatively distant formations above and below the wellbore, thereby helping to place horizontal wells in favorable locations and detect the spatial distribution of high-quality oil reservoirs. With the formation information provided by the high-end LWD tools, the evaluation of low-permeability tight sandstone is more reasonable. Under core calibration, the permeability calculated by using LWD NMR and Stoneley waves that characterize the characteristics of the microscopic pore structure is more reasonable than using a single conventional porosity, and the high-end LWD tools show the macroscopic and microscopic heterogeneity of the formation. It promotes the transformation of the development well type from directional wells to horizontal wells. At the same time, the application of Extra-deep geo-steering tools is not only conducive to the position adjustment of the well, but also provides the spatial distribution characteristics of the reservoir. It provides information for new well deployment. For the evaluation of the quality of low-permeability tight sandstone, the evaluation ideas from the perspective of pore structure and anisotropy have practical application value. LWD extra-deep geo-steering tools play an important role in the development of thick tight sandstone reservoirs with large lateral formation quality changes with shale interlayers. The application of advanced LWD tools in Oilfield A has achieved results. The current horizontal well production has reached the ODP design requirements, and a new round of drilling work has been launched.