Time-Lapsed 4D VSP and Micro Seismic Surveillance of CSS Thermal Heavy Oil Production in North Kuwait
Challenges in CSS thermal heavy oil production include how to monitor cap-shale integrity and steam flood effectiveness. Kuwait Oil Company has acquired baseline 3D VSP and time-lapsed 4D VSP in 2016 and 2017, and also recorded micro seismic during steam injection, as part of geophysical surveillance program in a heavy oil field in Northern Kuwait. This article presents a technical approach of the integrated interpretation of time-lapsed 4D VSP seismic inversion, quantitative interpretation, and micro seismic data for monitoring steam movement and cap-shale integrity. Applying high pressure and superheated steam in CSS operations can lead to damage of overlying cap-shale, which may in turn cause steam/reservoir fluid leakage through fractures. Time-lapsed 4D VSP technology has been proven to be able to image steam flood movement within reservoirs. Micro-seismic is also a useful tool to monitor and assess cap-hale integrity associated with CSS operations. 4D VSP Data Acquisition and Processing Field data acquisition consisted of a baseline 3D VSP in January 2016 and time-lapsed monitoring 4D VSP after second CSS steam injection in early 2017. Same acquisition parameters of 75 level 3-component receiver array tool with 2 meters of inter-receiver spacing was used for base and monitoring 3D/4D VSP in the same well. Simultaneously with 4D VSP data acquisition, micro-seismic data was recorded for 10 days to monitor any cap-shale damage due to steam injection. Processing technologies such as wave-field separation, down-going S-wave removal, deconvolution, enhancement of up-going P wave-field, static corrections and migration are used for VSP data processing in depth domain to get poststack data for future inversion and QI interpretation. All volumes of data are 1 m X 1 m X1 m bin sizes to enable the best possible resolution. VSP Seismic Inversion Simultaneous inversion of base 3D VSP and monitor 4D VSP was performed to estimate the layer-based properties and remove the effects of the wavelet. A high-resolution of AI outcome shows impedance change in steam injection zone. AI % difference between base and monitor VSP reveals temperature change in steam injection zone Seismic Quantitative Interpretation RMS attribute of seismic amplitudes each zone include reservoirs A, B and cap-shale was used for analysis of temperature change and cap-shale integrity due to steam injection.
AAPG Datapages/Search and Discovery Article #90334©2018 AAPG Middle East Region, Second EAGE/AAPG Hydrocarbon Seals of the Middle East Workshop, Abu Dhabi, UAE, April 16-19, 2018