This paper presents a unique successful application and implementation of testing procedures in an exploratory cretaceous well in Bahrah field (North Kuwait). Used to evaluate productivity and characteristics of a reservoir and clearly understand the reservoir's potential, which helps in reducing the risks related to developing the field for a long-term with sustainable production, and selecting the optimum completion and artificial lift method.
The exploratory vertical well BH-X drilled to explore the hydrocarbon potential within the Northern Area of the Bahrah field targeting cretaceous Sandstone formation, with a total drilling depth 10,780 ft. Open-hole logs and collected WL open-hole fluid sample post drilling proved the oil bearing in the sandstone formation. The cement bond evaluation behind slim casing liner showed some doubt in quality in particularly cement image of ultrasonic tool. Decision was taken to proceed with testing without cement remediation, and perform a DST with down-hole real-time pressure gauges. The Formation interval was perforated using dynamic underbalance casing guns post displacing the completion fluid in hole OBM with filtrated brine. The Nitrogen (N2) lifting through Coiled tubing (CT) was used for well activation and to evaluate the well productivity on rig since the well ceased to flow naturally. Since these pressure events and analysis are crucial in making decisions in a low cost environment, It was decided to retrieve the downhole pressure data for preliminary Pressure Transient Analysis (PTA), which indicated that the formation skin was positive. Therefore, acid wash was performed to the sensitive sandstone formation to enhance the production rate.
However, the results post the acid wash treatment showed increment in water cut. RIH with Water-Flow Log (WFL) to check the water source and identified channels behind pipe was challenging due to unavailability of E-coiled tubing. Thus, a unique solution was used to achieve a drawdown and dynamic condition while recording conventional WFL against the testing zone by using N2 and utilizing the DST tools functions. WFL results indicated the source of water behind casing above the test interval. Therefore, a cement squeeze job was performed and cement bond log was recorded again post the remedial job, which confirmed a good improvement in cement bond. The targeted interval was re-perforated utilizing dynamic underbalance perforation with STIM guns, the well was activated by CT using N2 lifting and showed clear improvement in production with zero water cut.
Overall, a unique methodology while using real time data has delivered better decision making and operational capabilities during rig and testing operations, which assists in reducing well testing operations cost and time.
