Abstract

With continual increase in water production from maturing reservoirs comes the expense of installation of surface handling equipment, disposal and environmental concerns and a reduction in production efficiency from hydrocarbon producing wells. These costs run into millions of dollars every year, dealing with this problem. The operators of these wells have utilized differing technologies and procedures in efforts to control production of these unwanted fluids. Water shut-off applications in one way or another are an everyday part of well servicing work. Some of the methods and practices currently used today to help combat this problem include, placement of cements, plugging back the zone with the aid of mechanical isolation devices, pulling the completion and performing work-overs, and the utilization of purposely designed cements or chemical water blocking agents. Initial efforts to utilize such fluids proved encouraging but methods were required by the operators in order to allow accurate placement of these chemicals. Some of the drivers are;

  • Economics, in terms of the relatively high cost of such fluids and;

  • The reaction of such water blocking chemicals when placed incorrectly within producing formations and the inability to reverse engineer such misplacements.

Couple these problems with the well geometry to be worked in and the solution of placement can be seen to involve many diverse complications. For this reason the requirement for innovative through-tubing zonal isolation solutions has never been greater. Through-tubing inflatable technology has, for some time now, been providing high-expansion devices in order to provide our industry with an economical and reliable method of isolating and placing water blocking treatment fluids. In this paper we will focus on current inflatable tools that are available today and how they can be utilized to provide cost effective water shut-off solutions at the source of the problem.

History

Coiled tubing deployed through tubing inflatable technology was introduced to the global oil and gas industry as long ago as 1985, with initial field testing conducted in the Prudhoe Bay oilfields of Alaska. These early tools were designed to allow for the selective acid treatments of lower zones without the requirement of having to first kill the well and then perform a full completion workover. The premise was to re-design existing tubing or drill pipe conveyed inflatable packing element technology devices in such a way as to make all the tool functions compatible with the limited workings of coiled tubing (limited push and pull and hydraulic actuation) while at the same time increasing the expansion, pressure and temperature capabilities of the tools. Early successes of these types of devices allowed for the rapid development of this new niche sector within our industry to a point today where we have many service providers supplying their end users with a choice of through tubing inflatable tools that offer almost as full an array of solutions as available in more traditional packing element style service tools utilized in a full bore type environment. Water and/or gas shutoff has probably been the most prevalent application for through-tubing inflatable tools - either as a bridge plug or cement retainer for mechanical wellbore isolation, or as treating packers for the diversion of chemical water isolation treatments into the reservoir. Here, the expansion capability of the inflatable tool allows water isolation while avoiding the often prohibitive cost of a workover or sidetrack, particularly in mature reservoirs with limited reserves. The tools available on the market today include but are not limited to both permanent and retrievable bridge plugs, single and resettable retrievable packers, permanent cement retainers, production and injection straddle systems and dual element selective stimulation and treatment tools. Coupled with the development of the inflatable service tools is the research, development and operation of coiled tubing, electric wireline and slickline running tools that when run in conjunction with the inflatable tool below will offer a safe, reliable and efficient system with which to economically provide an innovative wellbore solution to even the most complex of wellbore problems.

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