Umm Gudair (UG) field is one of the major oil fields of West Kuwait asset. Minagish Oolite (MO) reservoir is the main oil producer contributing more than 95% of the current production in the UG field. The field water cut has been increasing and currently is around 60%. The increasing water cut in the UG-MO reservoir is posing a major challenge in maintaining the oil production rate as the higher mobility of water compared to the oil will lead to a decline in the oil production rate and prevent oil producing zones from contributing effectively. The increase in water cut is attributed to the rise of the OWC and the natural water aquifer that underlays the oil column and extended across the reservoir.
UG-MO reservoir consists of different carbonate layers all are hydraulically connected with high vertical to horizontal permeability ratio (kv/kh) that ranges from 0.8 to 1.0. The high kv/kh ratio leads to water coning phenomena especially in the high pearmability zones. The petrophysical properties of the UG-MO reserviur shows lateral variation in permeability in each layer. The fluid PVT properties are consistent arcoss across the field with slight change vertically, the oil viscisity ranges from 2-8 cp and H2S and CO2 levels are 1.5% and 4%, respectively.
In order to address the increasing water production in UG-MO wells, the Field Development (FD)-UG team decided to implement Inflow Control Device (ICD) completions in deviated cased hole wells, open hole high angle deviated wells and horizontal wells. In addition, the work extended to install ICD completion in existing horizontal wells. The current total number of ICD wells in the UG-MO reservoir thirty-four
To maximize the success of the ICD installation campaign, the FD team along with the completion equipment provider have undertaken key steps in developing a robust design criteria and workflow upon the completion of the assessment phase. The assessment phase included a reservoir simulation study conducted by the asset with a third-party consultancy firm to determine the increased incremental oil and the decrease in water production from ICD completion implementation across the field, in addition to a metallurgy study to identify the suitable material for ICD completion to be used in the UG-MO reservoir.
The workflow included identification of the design objective for each type of well and consideration of the reservoir fluid properties and reservoir rock characteristics. The compartmentalization is based on the permeability that is estimated from recorded logs in addition to boundary mapper technology in some existing wells and the nozzles size selection is based on sensitivity runs on well-centric simulation models.
The performance of the ICD completions in UG-MO is showing good results and success in the new drilled open hole horizontal wells and high angle open hole deviated wells while the results of the cased hole wells showed limited success due to associated well integrity issues (e.g. poor cement jobs and ineffective remedial jobs) and the complexity of the completion with the presence of Electrical Submersible Pumps (ESP). Moreover, the performance of ICD as re-entry in existing horizontal wells showed moderate results.
The application of ICD will add value when the objective is clear, and the design criteria/ workflow is well defined and modified with time based upon the results and the performance evaluation.