Application Conditions of Binomial Regression Method for Reserves Evaluation of Geopressured Gas Reservoirs

Because the binomial regression reserve evaluation method for geopressured gas reservoirs is only dependent on pressure and production data, which is simple and practical, it is widely used for reserve evaluation in the middle and late stages of development of such gas reservoirs. However, if the application conditions are not met, it can result in large errors which may affect development decisions. Currently, there is a lack of systematic definition on the applicable conditions of binomial regression method. This paper starts with the basic principle of binomial regression method, and proves that the method requires certain applicable conditions through field examples. Based on the material balance equation, the similarities and differences between the binomial and the limit form type curve are compared, and the binomial applicable range is given, and the workflow of binomial regression method is established. The results show that the error from binomial approximation method depends on the parameters representing the product of compressibility coefficient and reserves λD. The larger the λD, the higher the error. When λD = 0.43, the error of binomial approximation method is 10%, and λD < 0.43 is the critical condition of binomial approximation. Finally, the reliability of the discriminant conditions is verified by field examples.