Data Driven Optimization of Sidetrack Operation Planning and Execution

Abstract

In the past year, a client in the Arabian Gulf has been increasing appraisal and development well activity from the same slot to reduce the uncertainty of reservoir depth, identify oil-water contact, and determine reservoir production strategy. The operator has been addressing these issues by drilling pilot sections from planned development wells, then plugging and abandoning the section prior to drilling the production lateral. The sidetracking operation is then performed from the previous casing shoe, aided by cement plug and landed to the required horizontal depth provided by the data from pilot section. Conventionally, positive displacement motors (PDM) have been used to perform the sidetrack effectively, then followed by a rotary steerable system (RSS) in the bottom hole assembly (BHA) combined with near-bit logging-while-drilling (LWD) tools to land the well. Because the pilot section is often drilled with water-based mud and penetrates through multiple layers of unstable shales and the reservoir, the hole condition normally deteriorates especially after extensive wireline logging runs, even after the cement plug has been set. In collaboration with other service providers such as cementing and wireline, the directional service provider revisits the sidetracking procedures to improve the sidetrack operation and reduce overall well construction time. Combining extensive data otherwise kept within each service provider's domain, the directional service provider analyzes the hole condition specific to each pilot section using formation evaluation data, wireline caliper logs, and pilot section drilling mechanics data to determine the sidetrack depth, drilling parameters, cement plug type, and the optimized RSS and BHA to perform the sidetrack efficiently. This detailed sidetracking procedure is then shared to all concerned parties, including to clients at the wellsite and in the office, and other service providers for discussion to align all objectives and ensure the sidetracking operation will be efficient. In 2018, the operator implemented the sidetracking procedures on 9 wells and achieved 100% success for drilling sidetrack from shoe-to-shoe in a single run. The detailed procedures mitigated the risks of using an RSS and subsequently eliminated the need to run a PDM to initiate the sidetracks. Comparative to sidetracks performed by the PDM, the sidetracking procedure using the RSS BHA managed to reduce drilling time on average of 1 day per well. The RSS BHAs also improved the hole condition for the subsequent activities of the well construction cycle, leading to less casing running issues and improved torque and drag for subsequent sections.