Abstract

This paper examines the use of coiled tubing deployed thru-tubing inflatable packers in a straddle configuration. Many times this straddle option can be used to prolong the life of a well without the time-consuming and resource-sapping operation of having to perform a complete well workover. Couple the resulting economics with the operational advantages of not having to kill the well and a completion in situ inflatable straddle option may and has offered operators in the global oil and gas industry a very real and viable option.

During the course of this paper the inflatable straddle option is examined and discussed as is the operational deployment and options of such a system. Running a single trip straddle and running a multiple trip down hole assembled system are highlighted. Four case histories will be disseminated to provide a balanced opinion on the effectiveness of such a system. The four case histories include a chrome system to match the already installed completion metallurgy and the highlighted wells will vary in geometry up to that of a horizontal gas well.

The paper goes on to discuss the longevity of such a system with at the time of submitting this abstract one of the featured systems having been in position in a producing environment for in excess of five years.

Introduction

There are many reasons for the requirement to run a straddle system into a wellbore. The most common application is the requirement to isolate a section of the wellbore while at the same time leaving the ability to access the wellbore below the isolated section. Some applications aim to isolate an upper or intermediate injection or production zone. Others need to isolate a damaged section of the wellbore or straddle a malfunctioning production packer. Still others provide a sealed velocity string or remedially install either flow control devices or sand control screens. A straddle option can provide the operator the option of prolonging the life of the well without the need of a workover. While a workover may well offer the most complete solution to the problem in hand there are reasons why a workover may not be the chosen way forward for the operator. These reasons may include logistics, equipment, time, matrix damage and cost, amongst many others.

For whatever reason, once a straddle option is selected, the choice of running an inflatable system will in all probability be based on the geometry of the wellbore. It would be very unlikely, for example, to select an inflatable system where a mechanical solution could be used.

History

The first deployment on coiled tubing of a thru-tubing inflatable element was undertaken in Alaska in 1986. Initial requests were to provide upper zone isolation in order to allow for coiled tubing treatment of the lower zone. In the intervening 15 years thru-tubing inflatable technology has advanced considerably with a market niche having been created. Today a thru-tubing inflatable tool exists for every known operation conducted on coiled tubing where more traditional remedial type tool systems exist.

It is now possible to plug, pack, squeeze, treat and straddle with an inflatable element on coiled tubing.

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