Proposal

By present hydraulic fracturing technology has advanced to reservoir systematic fracturing from single well’s stimulation treatment. Reservoir systematic fracturing has become an important economical treatment for low-permeability reservoirs since a great deal of wells have uneconomical productivity without fracturing. Therefore, it is very important to consider the requirements of fracturing treatments when programming the exploitation project for one new oil field or the future adjustable project for the old field.

Reservoir numerical simulation with hydraulic fractures is the basis of the optimum design of systematic fracturing. The numerical simulation software of systematic fracturing is developed, in which nine-spot pattern, five-spot pattern and rectangular well pattern are considered and both favorable and unfavorable azimuth of hydraulic fractures are included.

D37 is a low-permeability zone of Shengli Oil field in Shandong province of China. Five-spot water flooding pattern has been applied in D37 since 1990 while fracturing treatments since 1995. With systematic fracturing software, the production data has been predicting until water cut reaches 95% for systematic fracturing of five-spot water flooding pattern. By balancing the flooding sweeping efficiency and production rate, the optimum fracturing design is determined by giving a reasonable range of fracturing length and fracturing conductivity. The effects of nine-spot well pattern, azimuth of maximum permeability and injecting rate are synthetically studied. Integrating fracture propagation simulation with analysis of pumping pressure and history matching of post-frac productivity, ten fracturing wells in fD37 are evaluated. The reason why the production rates of some wells declined steeply shortly after the initial improvements is given in this paper. Based on the numerical simulation and evaluation of early fracturing treatment, design principles of systematic fracturing and rules of future exploitation in D37 are suggested.

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