Low Permeability Gas Reservoir Fracturing Of Horizontal Wells Can Predict Fracture Parameter Optimization

The development of horizontal well has become a primary method for oil-gas field development recently with improvement of drilling technique of horizontal well. The horizontal well can increase the contact area between wellbore and reservoir formation and drainage area, enhance single well productivity and recovery. However, the productivity and recovery is still low even making use of horizontal well technique for some low and extra low permeability reservoirs, which need to fracture treatment. Hydraulic fracture can produce several fractures to raise effectively flowing channels of oil and gas, decrease seepage resistance of near-well-bore and enhance the rate of recovery. In the paper, on the basis of analysis of the seepage flow characteristic and prediction of the single well productivity we have optimized the fracture parameters from predicting productivity and the optimized results can guide the program of horizontal well fracture treatment. The researches on fracturing for vertical and inclined well have been comparative matured. However, these researches are mostly based on the conventional reservoir circle and infinity boundaries, and there are few studies of the unconventional reservoir such as closed rectangular. The main works of the paper are as follow:(1) We preliminary analyzed stimulation mechanism of fractured horizontal well and fracture morphology and we also analyzed seepage characteristics of multi-fracture fracturing horizontal well combining with the seepages feature of horizontal and fracturing well. Then, the different pressure behavior typical curves were analyzed and seepage features of formation fluids in different phase were interpreted.(2) We developed the steady-state productivity formula of fracturing horizontal well in gas reservoir in the assumed condition considering the feature that gas is easy to compress and introducing to pseudo pressure based on the deduction method of productivity formula of fractured horizontal well for steady-state flow.(3) Aiming at the closed rectangular reservoir, we made use of the conformal mapping method and mirror overlay theory to develop horizontal well productivity model of single vertical fracture in the pseudo-steady-state condition and deduced the productivity prediction formula for multi-fracture fractured horizontal well in the paper.(4) On the basis of the verification of model in this paper, different feature parameters of effect on single well productivity were analyzed, and corresponding curves is drew. Then, we obtained the effects of different feature parameters on featured horizontal well.(5) We applied to the formula deduced in the paper and combined basic data for a horizontal well of low-permeability gas reservoir to predict the well productivity in different feature models and give a optimal fracture plan.