Recent technological advances in inflatable packing element design has allowed non-conventional workover techniques to be accomplished through the production tubing. The improved capabilities of these production tubing. The improved capabilities of these elements, coupled with new tool designs allowing workovers to be completed with coiled tubing or electric wireline, has seen growing applications. These workovers include, selective and zonal chemical treatments, temporary and permanent plugback operations, intermediate zone blankoff, production and injection flow profile modifications and formation fracturing. They are completed without pulling the production tubing from the well, and thus do not production tubing from the well, and thus do not require a rig on the well. Since these tools are snubbed in the well with coiled tubing or electric wireline, thus eliminating the need to kill the well, heavy weight kill fluids, which may cause formation damage, are not required. These tools have been designed to operate with hydraulic pressure and workstring tension within the coiled tubing limitations.
The advancement of this technology has led to a major cost saving alternative to conventional rig workover techniques. The recent improvements made in this equipment has substantially improved the capabilities and reliability of these methods. Major operating companies, utilizing these methods, have realized substantial cost savings in their workover programs.
This equipment has been designed to run through major sizes of production tubing and set in the larger production casing below. The inflatable elements have production casing below. The inflatable elements have the capability of being set in casing diameters over three times their run-in diameter. The tools may also be utilized in wells with much higher temperatures than previous technology allowed.
This paper outlines the development of these Thru-Tubing systems and application techniques that have been developed as a result of their field use. It discusses case histories of applications using this technology and the resulting increase in well performance. This paper also describes auxiliary performance. This paper also describes auxiliary equipment that has been developed to allow these tool systems to be used safely on coiled tubing and electric wireline.
An alternate method to complete workover operations has been developed within the last few years. This method involves running Thru-Tubing inflatable tools through the production tubing and setting them in the casing below to perform zonal isolation for the workover process (Fig. 1). The production tubing, therefore, stays in place throughout the workover operation, thus making recompletion after the workover unnecessary. The dramatic improvements in inflatable packing element design made within the last few years has now made the expansion and differential pressure requirements for this type of service possible. pressure requirements for this type of service possible. The ability to run tools through the production tubing has obvious advantages in the time that is required to complete these workovers. The inflatable tools used to conduct these operations have been designed to be run on coiled tubing. This makes it possible to perform workovers without a conventional rig on site, another economic advantage, Coiled tubing conveyance of these tools also makes it possible to conduct workover operations without killing the well, since the tools are snubbed in the well. This eliminates the possible formation damage that can occur when heavy weight kill fluid is used to control the well.
All of the Thru-tubing tools that have been designed are centered around the inflatable element.