Abstract:

Poor reserve quality, high water-cut and high investment cost have become the bottleneck of developing Dongsheng Gas Field located in Ordos Basin. In this way, the star evaluation management model is put forward to enhance its production performance. It is aiming at maximizing reserve value and investment benefits through geology-engineering integration. In the process of its implementation, the well locations, well patterns, drilling, fracturing and production technologies are optimized comprehensively, then the optimizedinformation is employed to improve and instruct future planning, thus the iterative improvement is achieved from single well to the whole gas field. Finally, the internal rate of return is calculated to determine the implementation sequence for each well. On the base of intelligent gas field construction, the above achievements are reinforced by organically combining downhole management with ground coping facilities, then the higher level of integrated development of geological engineering is realized. The following main results have been achieved: ①The detailed reservoir description and evaluation methods are formed for complicated high water-cut reservoir, and the gas layer penetrating rate raises by 20.8 %. ②Hierarchical constraints system for well network optimization is established, and the reserve production rate increases by 28 %. ③The drilling technology with both borehole stability and leakage prevention being considered is innovated through the combination of logging and seismic technology, and a completion string with slim hole and narrow gap is optimized to cater its demand. After optimization, the drilling cycle is shorten by 51 %, and investment cut by 31 %. ④The “large displacement, short time and high sand ratio” fracturing method is implemented, with the vertical well output increased by 56 %, and horizontal well 39 %. ⑤The “multi-parameter quantitative identification, coupling of nozzle and pipe flow, foam drainage and gas recovery system and production and injection technology in the same well” is combined together to lower the utilization limit of gas saturation to 45 %. Ever since the 13th Five-Year Plan, the production indicators of Dongsheng Gas Field are continuously improved. Moreover, a quantitative, operative and evaluable geology-engineering integration development model, with actual value of promotion, is formed.

Key words: star evaluation management, geology-engineering integration, high water-cut gas field, hard-to-recover reserves, fracturing