Transient Wellbore-Pressure-Buildup Correlation Helps Engineers to Ensure HIPPS Safe Operation

The objective of this study is to develop a correlation for transient wellbore-pressure buildup and relate it to the high-integrity pressure-protection system (HIPPS) response time in multiphase flow. The developed correlation gives an accurate estimate of the pressure buildup with time under shut-in conditions. It provides guidelines to set the HIPPS activation pressure considering different reservoir and wellbore parameters to ensure the safety and timely response of HIPPS. The correlation was developed by performing transient simulations to calculate the wellbore-pressure-buildup time under shut-in conditions accounting for different reservoir and wellbore parameters. The input data were gathered from three oil fields with various fluid properties, reservoir pressures, productivity indices (PIs), depths, and shut-in wellhead pressures (SIWHPs). Before feeding the data to the dynamic flow simulator, the reservoir data were tuned to match the well-flow conditions. After completing the transient simulation for every well, the pressure-buildup data as a function of time were collected and used as input to develop a correlation using the nonlinear-regression method. The results of this study show that the most influential parameters on the pressure-buildup behaviors are fluid compressibility, PI, flowing wellhead pressure (FWHP), and well measured depth (MD). In addition, we observed that there is a strong relationship between the fluid compressibility at FWHP condition and the time it takes to pressurize the wellbore to maximum pressure. The higher the fluid compressibility, the longer it takes the system to pressurize. The newly developed correlation provides a guideline for setting the HIPPS activation pressure and ensuring the wells’ safe operation.