Challenges and Achievements of Drilling Record MRC Wells for Appraising and Developing an Offshore Tight Carbonate

Abstract

This paper describes the field development planning strategy for appraising and developing an offshore reservoir area via extended reach extra-long maximum reservoir contact laterals drilled from an artificial island. These single production and injection laterals are completed in excess of 20,000 ft on top of tens of thousands feet of drilled well path to reach the drain landing point. These laterals have a dual purpose, as in addition to reservoir appraisal, is to maximize the productivity and injectivity in an on-going development of a tight carbonate reservoir. The well planning process starts from a careful selection of reservoir target coordinates to maximize the oil in place being developed from the artificial island and to enable reservoir testing and appraisal. From this data, initial 3D well designs are generated based on island location and rig capability to ensure ability to drill and run completion to total depth. The generated well tracks are used in a reservoir model to forecast production uplifts and inflow/outflow profiling along laterals. A strategic drilling step-out program has been implemented to extend drilling reach and completion deployment incrementally along with a reservoir surveillance program. The program was designed with built-in risk mitigations for any potential drilling and completion issues. The implemented program has enabled drilling into new areas and testing the reservoir properties at a small incremental cost of extending horizontal laterals. This has led to huge cost savings versus a very expensive appraisal program from a wellhead platform that included drilling a new well in addition to topside facility changes and pipelines conversions along with associated maintenance costs. The data gathered from these wells have enabled reduction of geologic uncertainty and de-risking of future developments. As a result, the field development footprint of developed oil resources was extended by additional 20% without the requirement of building additional drilling structures. Additionally, there is a well count reduction via lateral extension thus leading to capital costs saving. There were initial challenges encountered during lower completion deployment but they were resolved successfully in subsequent wells. An outcome of this strategy was the successful drilling of maximum reservoir contact wells with tens of thousands feet of drilled well path to reach the drain landing point and then with single horizontal drains exceeding 20,000 ft. The drilled wells resulted in unprecedented records in UAE and globally in terms of well total length, horizontal drain length and completion deployment.