Offshore Oil accounts for 30% of the world's liquid hydrocarbon production. As offshore platforms age, as is the case with some of the production facilities in the Gulf of Suez, these structures will have a increased load restriction, which makes it difficult to perform simple interventions, and forces the operator to deploy a Jackup rig or do a barge assisted operation. Some identified opportunities are not performed due to the high cost and the inherent subsurface uncertainty with brownfield assets. An alternative solution is a new generation intervention tool that allows signal transmission on conventional slickline wire. Real-time slickline (DSL) perforations use a unique technology to allow signal transmission on a standard slickline. The technology uses downhole battery-powered telemetry embedded in the downhole tool string. A radio-frequency (RF) antenna installed below the stuffing box is responsible for sending & receiving RF signals through the wire. The wire is coated with a proprietary engineered coating to ensure quality signal transmission and protects against corrosive wellbore fluids. The technology allows real-time depth correlation, pressure, temperature & vibration measurements while perforating. Moreover, the technology offers on-command explosive triggering, which improves safety over the older memory/timer version. Real-time slickline perforating was successfully introduced in the Gulf of Suez, accessing two platforms with structure load weight limitations that could not accept a conventional e-line unit. The optimized weight of digital slickline equipment was only 8 tons, compared to 35 Tons for e-line. Two wells were successfully perforated on two different platforms, adding 1200 BOPD at 10% of the rig-assisted intervention cost. The real-time slickline deployment enhanced the intervention efficiency and saved $950,000 in operating expenses. In addition to the successful deployment of several perforation runs without operational problems, the additional capabilities of DSL for surface readout (SRO) pressure & temperature data allowed the operator to optimize the time on the platform and maximize efficiency. The ability to add feedthrough jars to the string helped complete one job when the tool BHA struggled to get into the tubing after perforation. This capability is not available in conventional E-line. Real-time slickline (DSL) operations are the next generation for rigless interventions providing access to wells that e-line could not cost-effectively intervene and complete this task at a much lower cost.
This paper represents a challenging rig-less intervention in highly deviated wells with heavy oil that has always been a challenge to conventional electric line (e-line) that is not a valid intervention technique due to its inherent limitations in these harsh environments. Electric Coiled Tubing (E-CT) was utilized not only to achieve safer deployment of the guns, but also to allow real-time operations on three wells which were inaccessible due to heavy oil content and restricted e-line accessibility. A case study is presented for a campaign performed using E-CT to convey the perforating string while pumping nitrogen (N2) to lift the well and achieve flowing under-balance to maximize perforation clean-up and minimize skin. Real-time readings from gamma ray, pressure and temperature sensors were used to accurately position the guns, generate the desired dynamic underbalance, and finally validate successful detonation based on pressure and temperature responses. This was achieved while N2 lifting and firing the guns to optimize the required under-balance value providing immediate feedback related to the production gain to determine the zonal contributions and maximize the economical production gains. Dynamic wellbore behavior software modeling was also used to predict the dynamic under-balance effect for maximizing perforation efficiency. Deployment of E-CT was very challenging in terms of operational execution but was extremely beneficial for the safety of the pipe during such operations. A total of 13 runs comprising of milling, tubing cleaning and drifting were performed to remove the accumulated scales inside the production tubing and to ensure full accessibility to target intervals. Coiled Tubing (CT) dynamic modeling software was utilized to simulate the N2 rate needed to achieve the target underbalance while maintaining safe perforating parameters for the CT while firing the guns. As a result of software simulations, one of the three wells was then recommended for an acid wash treatment which achieved very effective results. 15 perforation runs were performed on the three wells re-perforating a total of 188 ft of interval, resulting in a production increase of more than 300%. This was a significant improvement compared to the previous campaign carried out in 2017 where perforating in static conditions showed no increase in production without work-over rig intervention. E-CT intervention also eliminated the need for waiting on rig schedule and avoiding deferred production.
Through tubing perforating guns that are deployed by means of electric line has been the most economic perforation technique to provide connectivity between the pay zone and the wellbore in cased hole wells. Conventional E-line guns was the most common type of guns used, however during the last two decades various types of guns has been raised to improve the perforation efficiency. In offshore operating companies including Gulf of Suez Petroleum Company "GUPCO" rig-less perforation has been proved to be the cheapest stimulation method, in case of re-perforating an existing interval, when compared to coiled tubing jobs that requires rig-assist or even acid bull-heading which will need at least a fully prepared vessel for chemical tank storage in addition to the highly cost acid itself. Moreover, it is much cheaper than tubing conveyed type that is always accompanied with rig work-over. So using dynamic under-balance gun has become a smart solution that will recover all debris in perforation tunnels in order to achieve the maximum oil recovery. When using conventional guns for re-perforating existing intervals there is a large contrast in the degree of success, and it was obvious that in law draw-down wells re-perforating the low productivity intervals has minor improvement and in most cases it was useless this was latterly explained to be resulted from the insufficient underbalance. In this work, implementation of a specific type of guns (Dynamic under-balance perforating guns) will be presented. The mentioned type generates in-situ underbalance creating an instantaneous and controlled surge of formation fluids into the well, which cleans the perforation tunnels up to 97% and enhances the well's productivity. The dynamic under-balance perforation technique has been tried in four wells that seemed from production logs are contributing with little share or sometimes not sharing at all which has been attributed to skin effect. After re-perforation, the results were outstanding with an increase of 20–40% in the total liquid rate and incremental increase in the oil rate with more than 2000 BOPD in the mentioned wells. The stated results revealed that the oil-bearing intervals are now competing with the high productivity high water cut intervals which considered a valuable gain with considerable very low job cost. The new guns type has proved its success especially when compared its results with the previous re-perforation jobs using conventional guns in the same wells where the incremental oil gain was much less. It can be used as a cheap alternative for near well-bore stimulation jobs especially for offshore platform wells.
Scale deposition is a major concern in Gulf of Suez Fields, variations in water composition and operating conditions resulted in the deposition of full spectrum of scale depositions in different fields. The common practice in GOS is to prevent scale deposition by periodical scale inhibition treatment. However the field experience showed variation in efficiency of inhibition under different operating conditions which results in some cases in scale deposition. In this case we are obliged to react and do intervention to clean out these wells either with chemical dissolution or coiled tubing clean out which is sometimes becomes costly and stand clueless in front of hard scale. Typically, in offshore operating fields, rig-less solutions is the optimum. A simple, innovative, and cost effective Torque action debris breaker tool is a new rig-less solution deployed on slick-line unit. The tool can be run at different sizes to allow for optimum scale removal. Activation is achieved via downward jarring action. The TADB tool applies a new operating concept different from milling. The tool consists of a sharp knife with a broach body. The operating mechanism uses the jarring down action in order to apply jackhammer force on the scale accumulation, which allows decreasing the bond between different layers of scale and between the scale and tubing. Another advantage is having the knife rotating after each jar action, which allows this force to be applied on different positions of scale accumulation adding more efficiency. The tool was first deployed in Egypt in one of the challenging oil wells offshore gulf of suez, which has a historical scale deposition issues "mainly hard deposition of zinc & lead sulfides". several trials were performed to clean out the well historically using coiled tubing operations using barge assist, it took 2 months of operation to achieve partial success & the well was worked over later. The Torque Action debris breaker was tried against the same scale type and found successful. allowing the well to be drifted with 2.7" compared with 2.25" before the job. The operation cost is by no means comparable to the previous cost of coiled tubing operations. Following this wells three other wells were intervened using the same tool and showed much better progress of scale clean out in comparison with other slick-line tools & historical coiled tubing performance in these wells. The implementation of this technology has generally optimized operating cost compared to lengthy and costly CT/WO operation minimizing footprint, equipment, manpower, job duration, and provide a more environmentally friendly solution.
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