Novel Approach to Stimulation Design Optimization for Ultra-Deep, 200°C Temperature Formations: A Case Study in Kunteyi Block

Abstract

Abstract The kunteyi Block, a domestic gas field, poses unique challenges with its ultra-deep, 392°F high-temperature conditions. These extreme environments significantly challenge the safety and efficiency of well testing and stimulation. The block faces issues such as:1) Difficulty in reservoir coring and low accuracy in mechanical parameter interpretation from conventional logging data; 2) Challenges in fracture initiation under pressure constraints in ultra-deep (20,964 ft TVD), high-stress, high-angle wells; 3) Lack of experience in fracturing operations for ultra-deep, high-angle wells at 392°F. This paper presents a design methodology and process tailored for ultra-deep, high-temperature, high-angle wells. It begins with cutting test technology for in-depth rock mechanics testing, followed by an innovative mechanical specific energy calculation method, factoring in actual drilling bit selection. This approach, combined with rock mechanics parameters, facilitates the identification of optimal cluster locations. Key construction parameters like inter-stage spacing, perforation cluster number and hole count, measure displacement, and fluid volume were further refined through three-dimensional fracture expansion modeling. Moreover, for a suspected aquifer 30 feet below the first section, a targeted low-displacement, small-scale acidification process was implemented. The results demonstrate that this method effectively quantifies the rock mechanical parameters of the Kunteyi Block. The optimized perforation locations achieved lower breakdown pressures of 13,778 psi; an 8.5% reduction compared to neighboring wells at 15,055 psi. The high-angle wells, segmented into four stages with differentiated fluid scales ranging from 56,504 to 63,566 cubic feet and a pump rate increase from 18.9 bpm to 62.9 bpm, enabled efficient fracture initiation. The implementation of small-displacement acidification effectively prevented communication with the water layer, thus enhancing the project's feasibility. This paper validates the effectiveness of cluster location enhancement using cutting tests and mechanical specific energy methods. These findings offer valuable insights and practical experience for the efficient stimulation of ultra-deep, high-temperature, high-angle wells.