Lesson Learned from the Hydraulic Fracturing of China's Shale Oil Field

Abstract

Abstract With the gradual deterioration of oil and gas resources quality, more companies are targeting the unconventional reservoirs. In China, unconventional reserves have accounted for more than 80% in total newly found proven reserves, taking tight oil for an example, China has tight oil geological resources of more than 12 billion tons. In this paper, we firstly introduced the main geology and reservoir characteristics of the target block, the strong formation heterogeneity, low permeability, low abundance, etc. This kind of reservoir has no economical production without hydraulic fracturing, while the stimulation operation still faced with difficulties such as un-predicate fracture propagation, high cost and low efficiency. Aiming to solve these difficulties, we summarized the status, experience and field application of the main hydraulic fracturing technologies in this area. (1) Horizontal well multi-stage fracturing (HWMF) technologies, featured with small well spacing, dense cutting, large fracture stages and small clusters, were widely used and applied as the main hydraulic fracturing method. (2) Widely used soluble sleeve bridge-plugs and soluble ball seats in the P’N’P completion wells, saving working time and reducing the construction cost. (3) Multi-functional fracturing fluids, featured with imbibition mechanism and increase oil recovery. (4) Replacement of ceramsite by low-cost quartz sand. (5) Factory-fracturing construction model, with maximum 12 well in one well platform. The integrated technologies have been applied in more than 200 wells, the daily oil production per well has increased from 3-5t/day to 15-25t/day. Application of the integrated technologies and the experience can be references for the efficient development of similar tight oil reservoirs.