A sectional optimization algorithm of perforation parameters of casing in horizontal water injection wells is established on the basis of triaxial in-situ stress of formation and the characteristics of flow fluid in porous medium. The triaxial in-situ stress of formation is obtained from acoustic logging information. Many affecting factors are included in the optimization algorithm, such as formation heterogeneity, pore pressure, pressure drop of oil reservoir, wellbore pressure drop and injection flow rate. The program of the sectional optimization algorithm is compiled by Visual Basic computer language, which is used to optimize the perforation parameters of casing of an actual horizontalwell named W73-P7. The results showthat the sectional optimization algorithm of perforation parameters in horizontal water injection wells can effectively optimize the distribution of perforation density along the wellbore, quantify the injection rate of each perforation section and improve the water injection efficiency. The optimization method lays a foundation for the analysis of injection effect and produces degree of surrounding oil well.
At present, the same perforation parameters along a wellbore are always adopted in the course of perforating, which is a common method of well completion. Due to the high heterogeneity of formation, permeability which is near the wellbore along a horizontal well is quite different from each other. The regions with high penetration have low filtrational resistance and early breakthroughs of water. In the meantime, it is difficult to injectwater into the low-permeability areas because of the high filtrational resistance. In order to improve development effects and enhance economic benefit, it is quite important to study the sectional optimization of perforation parameters of horizontal water injection wells. A great deal of research [1–3] has been done into the optimization design of perforation parameters along horizontal wells without considering permeability heterogeneity by domestic and foreign researchers.