Innovative Completion Methods to Overcome Challenging Multi-Stage Stimulation Completion Runs – North Sea Case Study

Abstract In the late 80's and early 90's, extensive hydraulic fracturing campaigns were executed to fracture many vertical wells in southern North Sea tight gas fields using the industries newest technologies at the time. In recent years, to boost production across two fields, campaigns involving modern horizontal, multi-stage stimulation completions were planned and executed to exploit the reserve pockets missed from historically only completing vertical wells. Three horizontal wells were planned in two fields in the Southern North Sea sector; two sidetracks and one workover for a well that was drilled to fracture in 2015, though the hydraulic fractures were never executed. Considerable efforts were put into detailed reviews of previously executed treatments in vertical wells to develop fracturing geomechanics, and the optimum fracture designs. Treatments were designed to utilize the same proppant and similar fracturing fluid recipes where applicable to optimize resource planning. All completions were multi-stage ball actuated completions to minimize interventions between treatments, with key learnings from successful operations in other high profile North Sea assets applied to increase operations efficiency. The wells were completed and campaigns executed in 2023. One well was successfully drilled and completed as planned, with all frac sleeves actuated and injections carried out in every sleeve. The multi-stage completion did not reach TD in the workover well, and real time decisions on alternative fracture sleeve locations were necessary, the result being the placement of only a single hydraulic fracture. The final new well involved an extensive fishing operation with drill pipe stuck in hole and required an inventive solution to save the well. A chemical cut in an optimum location for hydraulic fracture initiation was performed to avoid high-cost side-track operations. Fracturing strategies were quickly adapted to execute a single hydraulic fracture through the fish with an engineered over-displacement to remove the need to run coiled tubing in a high-risk non-conventional completion. All three wells produced remarkably well; the multi-stage treatment came online as the best producer in the field, and the two wells with the adapted completions met close to the well P90 production estimates with a single hydraulic fracture in each. This paper discusses the planning and execution of a fully utilized multi-stage completion, and the unique, real-time adaptations made in the high stakes offshore environment, as the operations evolved for two other wells to still achieve significant production uplift in these fields.