Minimize Risk and Improve Efficiency Associated With Electric Coiled Tubing Perforating Operations

Abstract

A perforating job conveyed with electric coiled tubing (CT) was recently completed in a high angle well offshore in the UAE using a combination of several new technologies which allowed this job to be completed safely and efficiently. Perforating operations with electric coiled tubing in offshore environments with restricted space have been considered hazardous and were avoided in the past because of the requirement to connect and finally arm the gun system while working at the wellhead below the coiled tubing injection head and other heavy equipment. Following the old standard operating procedures for explosive operations, arming the gun with the explosive detonator had to be done after the electric coiled tubing head was attached to the gun string. This gun arming activity is potentially hazardous as the work is being done in a tight space below very heavy equipment hung off on a crane line. Jobs using these old operating procedures were often cancelled as the potential risk to personnel and equipment was deemed to be too high. Also the length of perforating gun that could be run in one trip was severely limited by these procedures. Recently several new perforating gun and deployment technologies have been introduced to the field that make the electric CT perforating technique much more efficient and safe compared to past operations. These technologies includeA new expendable electronic addressable switch device providing electrical control and a safety barrier to each detonatorA simplified radio safe detonator which incorporates several intrinsic safety featuresAn electric deployment bar for perforating used to deploy the guns into a live well before the electric CT is connected. In addition to the above, a CT intervention was optimized to accomplish several tasks as part of the same offshore barge visit for a rigless intervention in a producing well with one CT rig-up. In addition to the perforation runs, CT was run to acid stimulate both existing zones and the newly perforated zone in the well. CT was also used to convey production logging tools to measure the production characteristics along the entire deviated section. This paper will describe how the combination of these new and existing technologies contributed to a safe coiled tubing perforating operation, improved overall efficiency and improved production from the well. There are many opportunities worldwide for perforating with electric coiled tubing and the application of these new technologies will enable more of these jobs to be attempted and to be completed safely and efficiently. Introduction Coiled tubing (CT) is being used more and more to convey tools and perforating guns into wells where it is required to maintain wellhead pressure control and push equipment into highly deviated or horizontal sections or carry heavier loads than a wireline system can handle1. Another advantage of CT conveyance is the ability to pump fluids into the well as part of the conveyance operation. Over the past few years more and more CT equipment is being fitted with electric logging cable (e-line CT) to replicate the features available with electric wireline operations, mainly surface readout of tool measurements and, in the case of perforating, being able to establish accurate depth control, fire the guns using electric detonators and using switches to shoot perforating guns selectively.