Volume 34: CCUS Technologies for the Carbon Neutrality: Part II

Application prospects of geophysical exploration techniques in the field of CCUS Chen Juan, Song Xilin, Liu Xuejun, Shi Yanling, Zhao Wenju, Yu Gang

Abstract

In the field of carbon capture, utilization and storage (CCUS), geophysical exploration technology can make great contributions and has wide applications. Injecting high-pressure liquid or gaseous CO2 into the existing underground oil and gas field can drive oil and gas moving in the reservoir to improve the output of oil and gas production wells and increase the recovery rate of oil and gas fields. At the same time, most of the CO2 can also be sequestrated inside the reservoir formation. Sequestration of CO2 underground is one of the important means and measures to achieve the goal of “Carbon Reduction”. Integrated geophysical exploration technologies have a wide application prospect in the CO2 storage site selection, onsite monitoring of CO2 injection process, and long-term real-time dynamic monitoring of the CO2 storage site safety. The high-density and high-resolution 3-D seismic, gravity and electromagnetic surveys can accurately evaluate the stability and sealing conditions of the underground geological structure for CO2 sequestration, and identify all faults and fracture zones within the CO2 sequestration site. Borehole seismic and borehole electromagnetic surveys can monitor and evaluate the CO2 injection process in real time to avoid any safety risks such as CO2 leakage from the injection well. In the underground area where a large number of CO2 is stored, the time-lapse borehole seismic and electromagnetic surveys can be used to map the migration and storage status of CO2 plume underground. Using the downhole armored optical cables outside the casing can conduct long-term real-time dynamic monitoring of the safety state of underground CO2 to prevent and avoid catastrophic events where underground sealed CO2 migration leaks to the surface. Over the past 60 years, gravity, magnetic, electromagnetic and geochemical survey methods have been widely used in the field of geophysical exploration. Therefore, they are becoming more and more popular in the oilfield technical service market. Nowadays, the state has put forward the requirements of “carbon reduction” for companies specializing in oil and gas exploration and development. BGP has focused on expanding its applications in CCUS during last three years. It has not only made contributions in the stability, reliability and tightness of CCUS storage site selection, but also made use of the advantages of optical fiber sensing technology for the real-time engineering monitoring of the CO2 injection operation. At the same time, it has carried out research on the long-term safety monitoring of CO2 sequestration sites aimed at preventing surface leakage. When applied to the field, it can provide real-time evaluation of CO2 driving the oil and gas moving, which is of great reference significance for reservoir evaluation and enhanced oil recovery. This paper analyzes the applications of the above-mentioned geophysical technologies on CCUS and makes a prospect from four aspects. It hopes to provide help to many oil companies make scientific decisions and accurately find oil and gas under the background of improving quality and efficiency and achieving the requirements of the national green energy strategy.

Keywords CCUS, CO2 sequestration, borehole seismic, optical fiber sensing, non-seismic