Successful Utilization of Extra-Long Lateral MRC Wells in Optimized Development of Tight and Thin Carbonates

Abstract

Abstract This paper is about the study and utilization of Extra-Long lateral maximum reservoir contact (MRC) wells for development of the tightest and thinnest reservoirs in a giant offshore oil field in the Middle East. The objective is to derive production buildup towards company's target as economical optimized development plans are needed to maximize resource value. The key reservoirs for achieving the buildup target are characterized by poor quality rocks with permeability ranging from 3- to less than 1-md. Also, one reservoir is relatively very thin with 8 ft of payzone thickness where the oil resource density is low. Reservoir studies were conducted to overcome the challenges of developing these reservoirs that led to optimizing well spacing, orientation, horizontal lateral placement and maximizing lateral length to achieve objectives. For example, in tight reservoirs a 250 m well spacing was utilized for effective pressure support resulting in a high well density. MRC wells up to a maximum of 20,000 ft in lateral length are designed to maximize the productivity per well in low permeability formations while reducing the total well count resulting in reduced project capital expenditure (CAPEX) in terms of drilling and surface facilities costs by 20%. Extra-Long lateral wells also helped in reducing any potential anti-collision issues with current and future wells. The optimization of number and sequence of Extra-Long lateral MRC wells is expected to accelerate production build-up and minimize drilling costs taking into account the limited drilling rig availability. The development plans also accounted for implementing mitigations in addressing potential concerns encountered in the MRC wells life cycle from well construction process to production/injection phase. In the drilling and completion phase, new technologies were implemented for the first time and have resulted in a world record of completing the longest 6⅝in. cased lateral with a lateral length of 20,000 ft in one trip. These technologies have enabled accelerated delivery and lower construction costs for wells through application of a standardized well design process that helped in streamlining the drilling operations while reducing any potential risks. In the production and injection phase, all MRC wells are cased with 6⅝in. limited entry liners (LEL) to ensure full lateral accessibility for well intervention and retrofit operations. The specially designed liners ensure optimal stimulation along the lateral by providing mechanical diversion of the stimulation treatment delivered at high rate to provide more effective, cheaper and simpler stimulation operations. The utilization of sulphate reducing plant (SRP) for injection water with lower sulphate and particle content will reduce the number of stimulation and scale treatment jobs. Finally, all the preceding technologies and mitigations have led to successful implementation of the plan evidenced by production results that exceed production rate expectations from these challenging reservoirs.