Abstract Predicting the performance of reservoirs helps engineers to estimate reserve, development planning which requires detailed understanding of the reservoir characteristics and production operations optimization and more importantly, to develop a mathematical model that will adequately depict the physical processes occurring in the reservoir such that the outcome of any action can be predicted within reasonable tolerance of errors. In this paper, software “REPAT” was built based on material balance and an expansion of Tarner's method by incorporating water influx and time concept to the material balance equation. The history matching process consists of modifying the aquifer parameters until an acceptable match was obtained within engineering accuracy. Example 9.2 in L.P. Dake was used as a case study. A STOIIP value of 311.48 STB was obtained with an error of 0.00195 and R value of 0.99999 which is an indication of a good fit, while the STOIIP obtained from MBal gave an error of 0.00253. The reservoir is supported by a combination of water drive and fluid expansion drive and Hurst Van Everdingen radial aquifer model was selected as the most likely case. The parameters used to obtain the history match and the STOIIP compare favourably with the expected values from L.P Dake and MBal. A good pressure and historical production simulation match was obtained.