Productivity prediction of horizontal well under oil and gas two-phase in low permeability reservoirs and influencing factors analysis——by taking Bohai A oilfield as an example

Horizontal well development has been widely used in low permeability reservoirs. If bottom-hole flow pressure is less than saturation pressure, the influence of two-phase flow should be considered when predicting the productivity. Based on the motion equation, a new formula for predicting the productivity in low permeability reservoirs is established, and the factors affecting the productivity sensitivity are analyzed. The example shows the prediction formula established has less relative error and higher accuracy. The results show the effect of starting pressure gradient on productivity is linearly decreasing. At the same horizontal section, the start-up pressure gradient increases and the production decreases. At different horizontal sections, the smaller the length of the horizontal section, the greater the impact of starting pressure gradient on productivity. When the stress sensitivity coefficient increases, the production decreases. When the stress sensitivity coefficient is less than 0.06 MPa~(-1), the impact of stress sensitivity on horizontal well productivity is smaller.