Optimized Completion Design with Ultrasonic High-Resolution Borehole Images and Formation Tester While Drilling- A Case Study, Offshore Abu Dhabi, UAE

Abstract Oil and gas fields in the early development phase require comprehensive data gathering to improve forward planning for their operation and life span. The data gathering is essential for formation evaluation analysis to help optimize the completion design. This paper details a case study conducted in a recently developed offshore mature carbonate field in the UAE, deploying the latest logging- while-drilling (LWD) formation tester and ultrasonic high-resolution borehole imaging technology. LWD technology has rapidly evolved in the last decade with improvements in sensor measurements and multiple possibilities for data integration, collaborative studies, and advanced processing. In many fields in the UAE, ultrasonic borehole imaging technology has been deployed to enhance understanding of the reservoir by combining borehole size and shape measurements with high-resolution radius and amplitude images. In highly fractured carbonate formations, deployment of this advanced technology with formation pressure testing tools has enabled the correlation of reservoir permeability with the geological features identified in the images. The data acquisition in this case study was conducted in an 8.5 in. lateral section, with inclination between 87° and 91°, drilled in an offshore carbonate formation in Abu Dhabi. The section was drilled with mineral oil-based mud (OBM), and LWD tools including gamma ray, azimuthal deep resistivity, density, thermal neutron porosity, formation pressure testing, and ultrasonic imaging sensors. The ultrasonic imaging tool logged the reservoir carbonates during drilling with a total footage of about 12,000 ft-MD. In addition, a total of 20 pressure testing points were performed while drilling across different intervals. The subsequent results from both measurements assisted in determining stress orientations, which further helped in analyzing wellbore stability issues. In addition, some intervals showed high porosity with low permeability. The ultrasonic image aided in fracture analysis, which was necessary for proper reservoir characterization. Pressure-point measurements, which had exceptional build-up stability in most of the intervals, helped to determine formation mobilities and hydrostatic pressures. Accordingly, the gathered information was used to optimize the packer placement in the completion design to target higher permeability zones for the required injection operation. The integrated LWD acquisition helped to update the reservoir pressure and mobility model in this area of the field. This practice will be widely used in similar applications to help increase injectivity in the target zones and meet the development plan objectives.