Research On Productivity Prediction Method Of Network Fractured Horizontal Well Based On Fractal Theory

Due to its poor formation property, it is a big challenge to develop the low permeability reservoirs efficiently. Horizontal well and network fracturing can enlarge the drainage area and improve the development effect. Hence, proposing a reasonable productivity prediction model of network fractured horizontal well based on the complex flowing pattern has remarkable importance on the development of low permeability reservoirs.Complex fracture network formed in the network fracturing has a certain fractal characteristic. In this paper we used a Y-shaped bifurcation network to describe the complex fracture network. Combining the point-source function and theory of potential superimposition, and taking the bifurcation angle, bifurcation degree, horizontal well length, fracture length fracture number into consideration, an unsteady productivity prediction model of complex fractured horizontal well was derived. Then, based on this productivity model, the fracture network’s influences on pressure field, flowing field and productivity were studied. The fracture network shape’s effect on productivity and remaining oil distribution was studied. Factors which have impact on productivity, such as fracture conductivity, horizontal well length, fracture number, fracture density, and half length of the fracture, were analyzed. Finally, numerical simulation method was used to verify each other. Results show that bigger bifurcation angle increases the drainage area, thus improving the production rate. When the bifurcation angle increases to a certain degree, the interference among the fractures branches become stronger and the production rate increase will be lower. Bifurcation angle and production time have a remarkable impact on the distribution of streamlines. Intensive streamlines appear at the tip of fracture. Because of the interference among the fractures, remaining oil mainly gathers in the middle of the complex fracture network. Parameters studied all have certain effect on productivity and there is a reasonable range for each parameter. Fractal dimension and bifurcation degree impact the stimulated reservoir volume. In the two-dimension space, cumulative oil production is bigger when fractal dimension is closer to 2.