Paper: A Special Sealant Process For Subsurface Water

Each year production is lost due to water influx from naturally occurring or induced channels or fractures. A special sealant process has been developed to help control subsurface water movement. The process consists of two individual states separated by a water spacer. Multiple treatments may be applied to control more severe downhole conditions. The first stage consists of about 200 gal/ft of a solids-free, non-Newtonian fluid with a viscosity of approximately 200 cp for matrix penetration. As much as ten pounds of solids per gallon may be added to this fluid for channels or fractures. This stage forms a very stiff gel when it contacts synthetic or formation brine. In fresh water zones where little salt is present, a preflush of concentrated brine is injected ahead of the first stage. The second stage consists of 10 to 30 sks/ft of low water-loss, accelerated cement slurry. This cement slurry is used to complete the special sealant process by forming a permanent, high-strength plug. To fit specific well conditions, solids may be added to the cement slurry. Successful sealant treatments have been performed in West Texas and New Mexico to correct subsurface water movement in producing wells. Most applications have been in naturally occurring or induced channels or fractures creating undesirable water flow. Sealant treatments up to 8,000 gal of first-stage fluid followed with 600 sacks of cement have been used.