Growing gas resource exploitation in Saudi Arabia has increased activity in drilling deep, high pressure gas reservoirs with marginal to low permeability. Such wells generally require stimulation operations to induce production. To increase the reservoir contact area, a significant number of wells are constructed with long reach horizontal sections. Multistage fracture operations are primarily conducted using plug and perforation technology to establish reservoir connectivity and production. The stimulation work involves multidisciplinary teams conducting simultaneous operations in a limited workspace and time. The primary well intervention challenges include the following:
- Effective deployment of cement and casing inspection tools in the horizontal section
- Safe, reliable, and efficient technology to convey the perforating bottomhole assembly (BHA) to the target depths in the long horizontal section during some stages of the plug and perforation operations
- Available, reliable, and readily deployable contingency perforating option for plug and perforation operations
High-pressure, high-temperature (HPHT) horizontal gas wells have traditionally been challenging for performing tractor operations because of reliability issues. Recent technical improvements have enhanced the operating range of the tractor, enabling more consistent and dependable operations in these environments.
Based on the experience of conducting several plug and perforation stimulation jobs in Saudi Arabia, the electric-line (e-line) tractor has proven to be a reliable and consistent well intervention solution. The tractor-conveyed cement evaluation tools have produced high quality interpretable data used to design the multistage fracture job. Post-fracture diagnostic work has also been successfully performed in the horizontal sections to evaluate tubular integrity, providing valuable information for future fracture design. Moreover, tractor-conveyed perforating has proven to be an effective solution for conducting stage-1 toe perforations in comparison to other options from several aspects. The option of contingency perforating in a closed system without fluid injectivity into the previously perforated stages has helped to maintain the continuity of operations. Successful tractor interventions have been performed in wells with more than 3,000 ft of horizontal sections, total depth (TD) of more than 17,000 ft, temperatures greater than 325°F, and pressures greater than 10,000 psi. This paper describes how the state-of-the-art technology has helped to meet the technical objectives of, and had a positive effect on, large rigless production enhancement.