Abstract
The company is executing an underground gas storage project at an unprecedented scale. The intent of this paper is to demonstrate the execution methodology and technologies that the company employed to achieve within set deadlines and deliver the work on time and under the given budget. This paper, therefore will focus on outlining all planning, design as well as drilling & completions strategies utilized by the operating company during the execution phase.
During Phase 2 of the project, the Drilling Contractor was engaged to deliver a total of 40 wells within a short period of time. These wells were planned to expand the total gas storage capacity at the Tuz Golu facility to ca. 5 bcm of natural gas stored in underground salt caverns. Tuz Golu wells are vertical with three (3) casing string wells. These land wells are big bore and commence from the installation of the 30″ conductor at a depth of 120m using a small 150-ton conductor rig.
Pre-installation of conductors significantly helped accelerate the project delivery schedule. Main drilling operations commenced in January 2020. Since the structure wasn't fully explored in spite of 2D seismic work and the first phase operations, a number of wells drilled encountered no salt leading to their abandonment. As a result, the total duration of the project was consequently extended. Re-Engineering and lessons learned during execution helped deliver a successful learning curve in both drilling and completion operations. The strategy of the company to drill a well in stages of top hole, main drilling and the completion using multiple rig operations was successful, bringing an overall well time from 55 at the beginning of the project to 20 days per well. Thorough planning and design of the wells allowed the company to deliver the projects with well integrity, full suitable for gas storage operations. As a result, the project was executed on time and well within the planned budget thus delivering an excellent value to the stakeholders and main client.
The Drilling Contractor has been proactive to employ this staged approach from the very beginning of the project. Irrespective of the delays the Drilling Contractor continued operations with the intermittent rig count of 4 to 8 rigs. A large scale operation demanded careful planning and continuous application of lessons learnt from the first phase which were successfully embedded and implemented.
