Abstract

Each year hydrocarbon production is lost due to water influx from naturally occurring or induced channels or matrix permeability. The complexity of correcting these widely varied water production problems in injection and producing wells manifests itself both in determining the cause and in formulating and executing the corrective measures. This paper emphasizes two sealant processes now available through advances in chemical technology.

Sealant one begins as a low-viscosity inorganic fluid that forms a stiff gel in situ after a predetermined pump time has elapsed. The placement technique involves pumping a calculated volume of sealant into the formation matrix, followed by a small volume of cement fail-in, at low pump rates and pressures. A long-lasting barrier to water production is achieved with a recommended volume of sealant.

Sealant two consists of pumping three chemical stages separated by a water spacer. The first stage is a brine solution. The second stage is a 200 cp, non-Newtonian, solids-free fluid which enters the matrix permeability. For channels or fractures where matrix penetration is not essential, as much as 10 lbs of other materials/gal of fluid may be added. This stage forms a very stiff gel when it contacts formation or prepared brines. The third stage is a low-water-loss, low-density, accelerated cement slurry to which solids may be added. This cement slurry reacts with the second stage to complete the sealing process by forming a permanent, high strength plug.

Successful sealant treatments have been performed in sandstone and limestonedolomite formations to control subsurface water in naturally occuring or induced fractures and matrix permeability, thus improving water-oil rations in producing wells. A survey of successful treatments demonstrates the adaptability of these two sealant processes, whether the need is deep matrix sealing or plugging of highly productive channels. In the vast majority of cases, water production problems can be remedied by the application of one or the other of these customtailored processes.