Smart One-Run Drilling Approach for Maximum Reservoir Contact Wells: Cost-Effective Well Construction Using Hanging Sidetracking and Multi-Boundary Inversion

Abstract This paper presents a cost-effective strategy for recovering residual oil in mature reservoirs. Traditional adjustment methods typically involve multiple drilling runs, including window sidetracking, landing, and horizontal sections drilling, resulting in high cost and poor residual oil targeting. The proposed approach integrates hanging sidetracking with multi-boundary inversion technology, enabling precise residual oil targeting through a one-run drilling operation, thereby enhancing economic viability and operational efficiency. Leveraging real-time near-bit inclination and azimuth data, this approach can help achieve precise trajectory control to perform hanging sidetracking within the upper mudstone section as close as possible to the target reservoir, maximizing the reuse of constructed wellbores. Multi-boundary inversion technologies can help deliver high-resolution stratigraphic visualization during the landing phase within a 9-meter radius, significantly improving landing precision compared to conventional methods that rely on the offset well data. Real-time visualization of residual oil distribution in the horizontal section facilitates dynamic trajectory adjustments, effectively addresses the oil-water distribution challenges typical of late-stage reservoir development and maximizes the residual oil contact area. Conventional cased-hole sidetracked horizontal wells typically require at least two drilling runs to complete sidetracking, landing, and horizontal section construction. In contrast, the proposed approach integrates all these steps into a one-run operation. By simultaneously dropping inclination and turning azimuth, the wellbore trajectory separates smoothly from the mother hole just 3.5 meters above the reservoir. During the landing operation, reservoir visualization was achieved 55 meters ahead of drilling bit penetration, eliminating the depth shift errors associated with traditional prediction landing based on offset well data. Also, this early visualization allowed for proactive trajectory adjustments, thereby avoided localized severe doglegs caused by premature formation landings. In the horizontal drilling phase, real-time delineation of the reservoir top boundary and the oil-water contact enabled dynamic trajectory optimization. It helped to position the trajectory in the most favorable zone and ensure an optimal water shut-off height, achieving a 100% sandstone encounter rate and a stabilized daily oil production rate six times higher than the original design forecast. Furthermore, real-time visualization of the oil-water contact enhanced understanding of reservoir water encroachment, providing critical insights and sufficient preparation time for subsequent completion operations. The proposed solution integrates sidetracking, landing, and horizontal section drilling into a one-run operation, significantly reducing operational time and costs. By enhancing landing precision and achieving greater reservoir contact rate, this approach improves recovery efficiency and offers a practical solution for the effective development of mature reservoirs.