Excessive undesired fluid production, either water or gas, is a widespread problem withinthe oil and gas industry that can detrimentally affect the profitability of hydrocarbon-producing reservoirs, thus limiting their economic life. A wide variety of chemical technologies have been implemented throughoutthe years for controlling unwanted fluid production with some degree of success. However, when these types of treatments are applied to horizontal or highly deviated wells, placement control becomes a critical factor. Depending on fluid density differences and wellbore deviation, conventional conformance treatments can slump/rise along horizontal sections, compromising the placement accuracy and overall treatment success. This paper discusses the development and application of a thixotropic conformance sealant (TCS) system specifically designed to help control unwanted fluid production in horizontal or highly deviated wellbores. The stress-dependent (thixotropic) rheological properties of the TCS system provides rapid viscosity increase afterplacement, allowing the treatment to remain in place until in-situ crosslinking occurs at a predicted time, helping provide a competent and precise seal across the targeted area.

The TCS system is based on an organic-crosslinked polymer gel system combined with optimized rheological modifiers. It provides a predictable and controllable crosslinking time to obtain adequate placement. It can be placed into the wellbore by bullheading or using a coiled tubing (CT) unit. Once it is strategically placed into the zone to be shut off, in-situ gelation is activated by the reservoir temperature, plugging the permeability of the treated area, thereby limiting undesired fluid flow. The TCS system can be formulated to allow penetration into the formation matrix or to bridge off at the formation face for limited leakoff, to help provide a controlled and shallow penetration at the formation face. Laboratory data ispresentedas well as preliminary results of field applications.

Other thanthixotropic cement slurries, the TCS system is the first conformance technology tailored to horizontal applications within the oil and gas industry, helping reduce excessive undesired fluid production while extending the economic life of the wellbore and reservoir. The TCS system is applicable to different completion types such as openhole, slotted liners, openhole gravel-packs (OHGPs), and casedhole gravel-packs (CHGPs), among others.

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