An onshore retrograde gas field in Abu Dhabi has several wells with severe liquid loading issue as reflected by low intermittent production rates. To overcome this, a study was performed by looking at the effectiveness of downhole and wellhead compression and their impact on the production rates. Utilizing IAM, the benefit will not only be seen at the well level but also at the field scale with the ultimate goal to increase the Recovery Factor.
The study was started by identifying the wells suffering from liquid loading issue. The wells were then ranked according to the severity of the problem based on the GLR values. Hence, the top 2 wells were prioritized as the candidates. Both the downhole and wellhead compressors were then modelled in IAM and several sensitivity runs were performed to evaluate the optimum compressor settings to see the impact on flow stabilization and wells productivity. The selected best scenarios were also compared with the base case as reference where no intervention was performed at all (natural flow).
The study reveals that both downhole and wellhead compression can give wells flowrate stability with substantial improvement on the production rates for longer duration of time compared to the base case scenario. More than that, the downhole compression shows better gain for production rates compared to the wellhead compression. This is mainly attributed to the fact that gas density is higher at the bottom of the well than at the surface and since the mass flow rate depends on the density of the gas and the volumetric flow rate, this will lead to higher mass flow rate for the same volumetric flow. Consequently, a downhole compressor will produce more fluid quantity rather than a wellhead compressor.
The study clearly demonstrates and evaluates the effectiveness of downhole and wellhead compressors to mitigate liquid loading inclusively to improve gas wells production. By utilizing IAM that is capable to capture the interactions between subsurface to surface network elements, the improvements on wells deliverability after implementing downhole and/or wellhead compression can be accounted more accurately taking into account more complex production operations with the ultimate goal to maximize the field Recovery Factor.