This paper presents the field implementation of a shallow-penetration conformance sealant (SPCS) system for water and gas control applications. This system combines an organically crosslinked polymer (OCP) gel system with fluid-loss control additives and noncement particulates. The additives/particulates provide leakoff control properties, which can lead to shallow matrix penetration of the sealant. This filtrate from the leakoff is then thermally activated at a predicted time. After exposure to the bottomhole temperature of the well, it forms a three-dimensional (3D) gel structure that effectively seals off the targeted interval. This system can be considered an alternative to conventional cement squeeze operations in scenarios where these types of treatments are not an option. The system can either be bullheaded into the wellbore or deployed with coiled tubing (CT). The limited and controlled leakoff into the matrix during the squeeze results in a controlled depth of invasion. Selective reperforation of treated zones is an option if the zone still has hydrocarbon potential. The system can be easily washed out of the wellbore compared to cement, which must be drilled out. Case histories are presented along with lessons learned from more than 250 treatments highlighting the diagnostic stage.
The SPCS system has been successfully tested to withstand a differential pressure of at least 2,600 psi and is resistant to acid, CO2, and H2S environments. (1) SPCS performance testing, (2) recent improvements to the system, (3) design considerations and best practices for field implementation, and (4) case histories are discussed. The working temperature range of this system is 40 to 400°F. To date, more than 250 treatments have been performed with the SPCS system globally to address conformance problems, such as perforation shutoff, gravel-pack isolation, fracture shutoff, poor zonal isolation, and/or casing-leak repair. Because of the capability of the SPCS system to withstand pressure, workover operations have been successfully performed in previously treated wells, including acid stimulation, sand control, and frac-pack treatments, among others. A primary objective of this paper is to help provide assistance during the candidate selection process and design of this particular sealant treatment.