ABSTRACT
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 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 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 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 equipment that has been developed to allow these tool systems to be used safely on coiled tubing and electric wireline.
