Successful Fluid Characterization in a Multiple Layer Carbonate Reservior for Production Optimization Using Formation Testing Technology

Abstract

The Middle Minagish formation is a major producing oil reservoir in West Kuwait where accurate formation evaluation is crucial. The complex carbonates of this field, coupled with a long history of production and water injection, gives a rise to the substantial variation of oil and water saturation throughout the field. These complexities necessitate a careful completion design for the optimal production. The objective of this case study is to show the success of the formation sampling and fluid identification in a multiple layer carbonate reservoir. The operation of the formation testing technology was conducted across the water zone, in challenging wellbore conditions and water-based mud. The timely, precise results aided to a better characterization of the reservoir and fluid properties.

A formation testing tool string was deployed in a deviated 8.5" open hole to acquire pressure data, fluid type identification prior to the well casing and completion. The main fluid typing sensors were resistivity, density, viscosity, capacitance, pressure and temperature. The formation testing program was accomplished successfully, and the objectives were met with the minimal fluid sample contamination, as validated later with the laboratory results, highlighting the real-time data precision for the decision making.

The formation testing and sampling data set was integrated with the open hole interpretation in real-time to support the well completion final design. Overall, the formation fluid identification and sampling data showed a clear discrimination between the formation and drilling fluids. In addition, a water sample was collected and later used for the water compositional analysis to test its compatibility for future field development applications.

A novel formation tester along with real time monitoring allow achieving the logging and welling objectives with high quality data. The results supported the selected well completion design and resolved uncertainties of the Minagish Oolite reservoir to maximize production and increase the operation efficiency.