Serhii Kryvenko, Texas Tech University
The fault effects on the build-up pressure distribution of oil wells were investigated by using numerical and analytical approaches. The limitations and benefits of analytical and numerical solutions of the build-up test were listed in the research. The effects of reservoir boundaries on well responses by using analytical solutions were analyzed. Schlumberger software package “ECLIPSE” was used for the numerical simulation, where the model was discretized to 200 by 200 by 5 grid blocks with the length of each side of the grid block as 75 feet horizontally and 7.5 feet vertically. The model with one production oil well and one injection well with the same characteristics were simulated to prove the well image theory, compare it to the analytical solution and validate the model. The boundary of the reservoir, excluding the fault, was never reached due to the presence of the observation well. Multiple cases, such as one sealing fault, two intersecting faults, semi-permeable faults were analyzed in the model. Horner plots and derivative type curves were built to define the signature of the reservoir. Sensitivity analysis was proposed for each case to provide the correlations between the reservoir parameters. Early time off-trend behaviour in build-up test data by using numerical approach was investigated. Semi-permeable fault signature was defined as the decrease of the slope on the derivative type curve after the establishment of the radial flow. The Horner plot in case of two intersecting faults showed the slope four times more than in case of a homogeneous reservoir.