Horizontal Wells, Multilateral Wells Production To Analyze Theoretical Research

In recent years, drilling horizontal wells and branched well has been becoming an important method of increasing production for oil and gas reservoirs development all over the world. So it is necessary to research their reservoir engineering and production performance. Using analytical approach, this thesis studies productivity analysis methods for horizontal and branched wells from the angle of reservoir engineering.First of all, this thesis discusses the productivity analysis method for horizontal well in reservoirs with different kinds of outer boundaries, analyses effect of horizontal well's length, position and anisotropy of reservoir on its productivity. Considering pressure drop of pipe flow in horizontal horehole owing to fluid acceleration, frictional resistance as well as radial-inflow, it couples pipe flow with percolation in reservoir and makes use of nodal analysis method and set up the productivity analytical roodel for horizontal well. Then, the steady-state productivity model for horizontal well in gas reservoir is established. On the basis of solving the model, this thesis deduces the binomial deliverabiliry equation by which absolute open flow potential and inflow performance relationship can be gotten and we can forecast the production performance of horizontal well in gas reservoir. In addition, a new approach to calculate the productivity of some branched well systems such as multi-lateral horizontal wells and complex branches that distribute arbitrary in the same horizontal plane as their original hole. It provides powerful tool and means for branched well system's productivity analysis and forecast in practice.In a word, this thesis researches the horizontal and branched wells productivity analysis theory and offers a series of approaches for optimum design, deciding rational working system of complex well and production engineering.