Abstract
Oil wells performance can be determined from completed zone productivity, completion type and size, and surface facilities. A significant surface tool, wellhead choke, can profoundly impact on the well performance. Determining the optimum choke size can result in improving the production of the well by altering the wellhead pressure, therefore the pressure drop. Increasing the bean size above optimum might result in decreasing wellhead pressure below flowline pressure and prevent the oil from flowing.
To determine the optimum choke size for oil well; live trial and error could be helpful, though it is not practical and need to be combined with a well simulation analysis and history matching. A multiphase flow simulator is applied on a set of selected wells, having bottlenecks and backpressure issues in Kuwaiti oilfields. The simulation has been developed by choosing a precise flow correlation that presents a reliable flow behavior and pressure drop results. A comparison of different flow correlations was performed against the actual test readings to eliminate a potential error from the simulation against the actual readings.
Changing the choke bean size was a quick, effective, and economical solution to overcome the bottlenecks and backpressure issues in individual candidates. Simulating the formation productivity and assessing the well performance and changing the choke size can increase the successfulness chance of the live trial and error procedure. It can also help in categorizing the wells whether to be a candidate to have choke size change, or another solution is required to flow the well such as a surface pump, artificial lift, or changing the receiving facility pressure, if possible. All the selected eighteen wells are vertical or slightly deviated with an oil API gravity between 32 and 35 degrees, and the flow behavior correlations were between the Beggs and Brill (1973) empirical correlation and the Ansari (1994) mechanistic model. The comparison between multiple sensitivity analyses proved that both models are reliable and can be applied to the selected field. Simulating the wells had increased the choke size debottlenecking approach successfulness rate by 70 percent, and increase the oil production up to 6,000 barrels per day.
A debottlenecking analysis is presented in this project, and supported with data matching and field test results. The procedure to optimize the choke size is explained in details using a multiphase flow simulator and an in-house developed excel sheet. Several additional approaches were analyzed to overcome backpressure issues, like using ESP artificial lift method.
