The evaluation of horizontal gas wells using routine logging tools is more challenging, when compared to vertical holes. The standard practice is to deploy logging tools on a drill pipe, typically known as Pipe Conveyed Logging (PCL), however, this standard conveyance method is risky and time-consuming. Therefore, this paper focuses on the optimization project to convert all PCL runs, including formation testing, into time-efficient operations by using groundbreaking wireline conveyance techniques.
Assessing fit-for-purpose alternative options is necessary to de-risk open hole logging operations. Firstly, a thorough review of the logging requirements was performed for reservoir section in each hole size, namely 8-3/8″ and 5-7/8″. Concurrently, the wireline conveyance techniques present within the services provider's portfolio, were evaluated against the normal borehole conditions, open-hole risk profile and potential saving opportunities. Thus, the tailored risk-based workflow created suitable conveyance methods for each application. It ensured that the newly initiated solutions matched with operational needs. Considerations were also made to upgrade the existing technologies to meet the logging objectives.
An extended-reach wireline deployed tractor system was implemented to pull the tools for over 2,800 ft of open hole of up to 87 degrees inclination, across highly depleted carbonates in the 8-3/8″ deviated section. This technology combines the use of an electric-driven tractor with low-friction taxi wheels. It provides better data quality due to enhanced tool stand-off and saves more than a day of rig time compared to a conventional PCL run.
In addition, in the 8-3/8″ section, formation testing runs were conducted using high-tension cables with up to 60 dg inclination, and maximum overbalance of 3,920 psi. Up to 14 pressure points per run were taken down to 13,700 ft without deploring any differential sticking incidents or tool obstructions.
PCL runs were replaced with through-the-bit logging services across the 5-7/8″ horizontal reservoir, typically stretching across 5,000 ft. This unique conveyance platform is designed for long laterals, and it consists of a suite of logging tools which is integrated to the drill string, allowing the combining of logging operations and reaming trips. Prior to running the stage-frac lower completion, the reservoir was successfully logged.
This innovative engineered approach was implemented across large scale, multiple rigs, in one of the most prolific gas fields, accelerating the learning curve of logging operations optimizations. It has helped to decrease risk and lower well construction costs, by saving more than one day of rig operation time. Thus, alternative conveyance methods will enable operators and service companies to work tightly together, driving logging efficiency in the Middle East and other basins.
