Geophysical Surveillance of a Steam Injection Project in a Kuwait Heavy Oil Field

Abstract

Abstract Kuwait Oil Company conducted a geophysical surveillance program to optimize development options in a shallow heavy oil field in Kuwait. Two optimized 3D Vertical Seismic Profiles (3DVSPs) were acquired in January 2016 to help understand the effectiveness of this EOR project. Goals of this project included acquiring repeatable baseline surveys for 4DVSP surveys, attaining high resolution 3DVSP data, imaging the sealing cap rock shale and two thin vertically stacked reservoirs, and estimating the steam chamber size just after a 30-day steam injection cycle. One major problem with recording shallow VSP data is the possibility of spatial aliasing due to the slow propagation velocities of P and S waves affecting the ability to achieve desired frequency range. Therefore extensive pre-survey modeling was required in order to determine the optimum source-receiver configuration. The team decided on innovative survey parameters purposely designed to obtain higher frequencies than previously attained in this area to improve the vertical and spatial resolution sufficient to achieve the project goals listed above. The resulting two 3DVSP datasets were then processed and imaged using a patented vector pre-stack Kirchhoff depth migration. Inversion work and qualitative interpretation were then applied to both data volumes to help achieve all the desired goals. Extensive planning and flawless execution of the two-well 3DVSP operation resulted in the completion of both survey acquisitions in a total of 13 days without incurring any QHSE incidents and having 100% operating efficiency. Frequencies obtained in these surveys were more than 30% higher than previously achieved in this same area. These high frequencies resulted in vertical resolution sufficient to image the sealing shale layer and both of the steam injected reservoir sands as well as the necessary spatial resolution to image a small steam chamber. The novel modelling, acquisition and processing/interpretation methodology described have demonstrated that accurate subsurface imaging in this environment is achievable. The results have contributed to and altered the steam flood expectations and will provide key information that would not otherwise have been available to develop the best development options. Additional 3D and 4DVSPs are currently being acquired. Extensive modeling enabled innovative customization of an innovative acquisition design, optimized acquisition operations, parallel processing, and interpretation techniques have allowed for a time efficient acquisition-to-results turnaround.