Hybrid Fracturing Treatments Unlesh Tight Oil Reservoirs Consisting of Sand Shale Sequences in the Chanfqing Oilfield

摘要

Low reservoir permeability and pressure are the key characteristics for the tight oil reservoirs consisting of sand and shale formations in the Changqing Oilfield in the Ordos Basin. In these tight reservoirs, regular fracturing stimulation with modest treatment sizes only yields low post-treatment production that cannot meet development requirements. Recent literature is bountiful in the successful developments of tight oil and gas reservoirs, especially from North America. After conducting literature review and learning from the experience in North America, hybrid fracturing tests were carried out in vertical wells, to improve well stimulation effectiveness in the Changqing Oilfield. Hybrid fracturing treatments for these tested wells yielded very good results with production enhancement at approximately 300% folds of regular fracturing treatments in the same reservoir block. Downhole microseismic fracturing monitoring and production analysis techniques were used to evaluate hybrid fracturing performance. In this paper, the ultra-tight oil reservoirs in the Changqing Oilfield were described, and hybrid fracturing treatments applied to the Chang 7 formation were studied with the aid of minifrac analysis, microseismic monitoring and post-treatment production results.