A Novel Approach for Well Placement Utilizing High Frequency High Definition Deep Resistivity Inversion in High Resistivity Environment

Abstract Conventional logging While Drilling (LWD) sensors have shallow depths of investigation (DOI), hence they are primarily used for reactive geosteering, the utilization of deep resistivity tools is crucial for proactive well placement in challenging geo-steering environments. Using deep resistivity measurements in complex mature carbonates presents a significant challenge due to the uncertain geological structure. With a wide range of resistivity values and poor resistivity contrasts common, a thorough evaluation of offset wells is essential prior to drilling horizontal wells. This paper presents the utilization of high definition, high frequency deep resistivity sensor for resolving low contrast boundaries to enhance well placement decisions in high-resistivity mature carbonate environments. Electromagnetic (EM) deep resistivity sensors produce multiple measurement components that fit into an inversion algorithm to provide a visual geology model for well placement decisions utilized for proactive Geosteering. Targeting high-resistivity low contrast environments requires detailed pre-well modeling and analysis of offset well data to identify the optimal deep resistivity inversion settings. Recent improvements in deep resistivity tools allow a wide range of EM wave frequencies to be acquired including high frequencies usually required to resolve boundaries in high-resistivity formations. These developments accompanied with inversion software developments also allowed for running multiple inversions while drilling having different combinations of EM spacings and frequencies to map high resistivity boundaries of poor resistivity contrast in addition to any potential water (conductive) zones below the horizontal wellbores. Well placement analysts interpret the deep resistivity multiple inversions in real time and take proactive decisions to place the wells in target reservoirs ensuring maximum reservoir contact and optimum distance from the conductive layers. A combination of deep resistivity and conventional LWD logs were utilized for successful landing and horizontal well placement within the target zone. Real-time evaluation of LWD data, coupled with correlation with offset well data has been used to validate the results of deep resistivity inversions while drilling. Furthermore, deep resistivity inversions mapped formations boundaries, dip changes and resolved multi-layer within the carbonate reservoirs characterized by poor and significant resistivity contrasts. Recent advancements in deep resistivity tools and inversion algorithms successfully addressed traditional EM deep resistivity limitations by utilizing a new rage of EM wave frequency to steer the wells within thin target zones of high-resistivity values and poor resistivity contrasts. This paper presents a novel development of EM deep resistivity tools and inversion algorithms to enhance well placement in high- resistivity carbonate environments.