OREANDA-NEWS. July 17, 2014. The technology of water shutoff treatment with cutting out part of the production casing is successfully applied at TATNEFT Company for oil recovery enhancement.

The technology of isolating behind-the-casing flows developed by the TatNIPIneft experts is applied to restore the integrity of the cement sheath and isolate beds of the pay section in the well in the absence of oil bearing horizons below the cut-out interval.

The engineering development has been field tested in more than 60 wells of TATNEFT and its use continues. Most of the activities were carried out in the injection wells. The success ratio of application of the behind-the-casing flows isolation technology with cutting out part of the production casing in the cross flow interval exceeds the success of similar operations carried out through a special hole in the production string by more than 15 percent.
Unlike other technologies of liquidating casing cross flows the objective of this technology is not sealing the cross flow channel, but creation of a new well lining in the cross flow interval.
The interval of the production casing cutting out is selected individually for each well on the basis of geophysical studies allowing to assess the technical condition of the filter and the cement ring in the sections adjacent to the filter.

In the process of the technology implementation part of the production string is cut out in the cross flow interval and application of expanding reamers allows removing the old cement stone and mud cake thus providing for optimal conditions of adhesion of the cement stone and the rock through increasing the cement slurry contact area with the formation.

The annulus and channels of water influx to the well are plugged with two possible options of the process completion: injection of the mortar leaving a cement bridge in the interval from the bottom to the lower edge of the producing formation drilled part, i.e. without leaving a sump, or running a liner in the cross-flow interval followed by cementing the liner in case of a sump presence.

The economic effect is achieved through reducing the water cut of products produced.