Enhancing Twin Well Lower Completion in Thin Formations Using Dissolvable Plug Nozzle and Non-Aqueous Fluid

Abstract The slim lower completion is becoming more widely adopted to optimize the production by using limited entry liner (LEL) configuration in horizontal wells. This design however, present numerous challenges. One of the factors that needs to be considered in lower completion deployment is the friction factor (FF), which represents an estimation of the entire string running behavior transformed into drag and force. This depends on well trajectory, fluid type, well bore condition, tortuosity and string configuration. In the initial stage, the trajectory is planned based on geological structure interpretation of seismic and offset wells. During the drilling phase, it is further refined with logging data interpretation. However, the actual downhole drilled trajectory will have uncertainty such as micro doglegs which can contribute to incremental frictional drag downhole. It is critical to maintain a smooth trajectory with a cut off dog leg severity (DLS) less than 1.0 degree per 100 ft in the horizontal section to minimize the tortuosity and prevent micro doglegs prior to deploying the lower completion. This poses a big challenge especially in thin formation and when there are uncertainties in the geological structure. Drilling 6″ horizontal hole with water-based fluid is the norm in onshore operations. It is efficient and has been shown to be cost-effective, even though it is known to have a higher FF than synthetic or oil-based fluid. Recognizing the problem of drilling in thin formation, synthetic based fluid known as non-aqueous fluid (NAF) was chosen as a control factor to reduce friction factor during drilling, resulting in an optimal trajectory and successful running lower completion. The lower completion is equipped with LEL principle which consists of uneven spacing of a limited number of small holes drilled through the liner to mechanically divert acid along the entire reservoir drain for stimulation. The dissolvable plug nozzle (DPN) technology was selected to have a close system for lower completion with LEL requirement which allow circulation to bottom of the string to counter obstruction and displacement purpose. The paper aims to present the experience and success story of running twin well 4-1/2" lower completion in thin reservoir with proper application and technology to counter the challenges.