The Theoretical Research On Productivity Of Horizontal Wells

In the process of developing oil field, the horizontal well technology has been widely applied in domestic and international petroleum engineering field, because of its advantages of large oil discharge area and small seepage resistance. But, it also increases the cost and technical difficulty when it increases oil production, and even some horizontal wells yield is very low and economic benefits is not ideal. Therefore, it's that horizontal well cannot produce very good development effect in any situation. So, it is necessary to do thorough and comprehensive research on the basic theory of horizontal wells, such as, seepage theory, productivity analysis theory to make horizontal well technology show its effect adequately.There are lot's of problems need to be studied deeply in the aspect of horizontal well productivity, currently. The paper focused on the following:(1) The paper established new horizontal well steady-state productivity equation on the base of the thorough and comprehensive research on the classical equation. The paper decomposes the three-dimensional flow into two two-dimensional flows of horizontal plane and vertical plane, and then studies it with the radial-flow model and the direction flow model respectively to get new horizontal well steady-state productivity equation.(2) In the process of developing oil field, the production of horizontal well will be affected by many factors, the paper do thorough and comprehensive research on three aspects of the reservoir characteristics, Oil Wells characteristics and formation damage with example curve with examples.(3) From its start-up pressure perspective,established horizontal well steady-state productivity equation of low permeability reservoirs for its characteristics of low permeability of the non-Darcy seepage flow. The impacts of start-up pressure and production pressure on its production are analyzed with practical examples of instances.(4) Established horizontal well steady-state productivity equation of gas cap reservoir, edge water reservoir, top and bottom closing reservoir and bottom water reservoir with the mirror reaction, the potential of the super position principle and the equivalent flow resistance law.(5) Established the correction formula of oil-water two-phase flow of bottom water reservoir, and it is proved to be accurate by practical examples;Analyzed the theory of bottom water ridge and it's stable conditions. (6) The common formula of bottom water coning critical production and the derivation of critical produce pressure are shown; The influence factors of critical produce pressure of bottom water reservoir are researched thorough and comprehensively.