| Horizontal branch well technology is an important new technology which meets the current oilfield development need. Its productivity prediction research is an important content of oil-gas development project.Based on the summarization of preciously existing results, this paper utilized conformal transformation, mirror image, potential superposition principle, equivalence filtrational resistance method to derive the productivity calculation formula of radial horizontal branch well in 3D space. With this formula, this paper analyzed the horizontal length, stratum thickness, the number of horizontal branch, permeability anisotropy, oil well position and supply radius etc factors to influence the productivity of horizontal branch well. Meanwhile, the filtration theory of radial horizontal branch well was studied in this paper. Based on the mirror image and potential superposition principle, it also derived the potential distribution formulas of horizontal well in unbounded strata and established the potential distribution formulas of horizontal well in bottom water drive reservoir, edge water drive reservoir, gas cap and bottom water drive reservoir and ordinary reservoir. Based on this formula, it deduced the space potential distribution formula of production section of the complex horizontal branch well; And adopting infinitesimal line sink theory and momentum conservation theorem established frictional pressure drop calculation model of production section of the complex horizontal branch well; On this basis of infinitesimal line sink theory and potential superposition principle, it derived coupled mathematical model of reservoir seepage and wellbore variable mass conduit flow of production section of the complex horizontal branch well and gave its solving process.Through the study, this paper perfected the theory and method of horizontal branch well productivity prediction and provided theoretical basis for the development design and deliverability analysis of horizontal branch well. The paper deduced the productivity calculation formula of radial horizontal branch well. This formula, which has certain theoretical and practical value, can be used for productivity prediction of the radial horizontal branch well in reservoir engineering and provides theoretical basis for the productivity prediction of complex horizontal branch well. |
