Munga field of the Greater Nile Petroleum Operating Company (GNPOC) in Sudan has several wells that have commingle production from the Aradeiba, Bentiu-1 and Bentiu-2 formations. These formations are highly variable in terms of the reservoir properties, oil types and pressure regimes. Because of the contrast properties of different layers, the water cut phenomenon is relatively fast and severe which hampers the productivity and ultimate recovery of the individual well as well as the field.For effective Reservoir Management and to limit the declining trend of the field, Water Management Techniques are applied in some of the wells of this field. Information obtained in the process was used for reservoir model calibration, well productivity prediction, low productivity diagnosis, and generation of new drainage points and remedial action for water management. This paper discusses the technical details of three cases corresponding to the wells Munga-XX and Umm Sagura South-XX (USS-XX) and Munga-XY in which, a multidisciplinary approach has been implemented in order to determine depletion profile, produced oil and remaining reserves, locate any "by-passed" oil zones, determine oil and water contributions from each zone and shut off the excess water production while maintaining or increasing oil 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.

Perforating a gas well efficiently requires applying technological advances to carry out a safe operation without compromising well productivity. In this paper, is discussed the application of a pre- job plan methodology called perforating well on paper to the perforation operation of SITRA 3-4. This methodology involved tension simulation, perforating gun and charge selection, conveyance hardware optimization, best underbalance value selection, as well as modeling of gun shock, gun movement and reservoir behavior when shooting multiple zones with different pressure regimes. Simulation methodology was performed as well real time during the perforating job to optimize static and flowing underbalance without compromising the safety of the operation and maximizing production gains.

Through Tubing Mechanical Shut off Process using electric line has been an economical and successful way to isolate undesired perforated intervals in cased whole completions. During the late 1980s & early 1990s the technology became more reliable so the oil & gas industry began to put more trust in eline capabilities for the through tubing shut-offs. Many of offshore operating companies including Gulf Of Suez Petroleum Company "GUPCO" adopted the technique in order to minimize the number of rig work overs and accelerate add rate activities using rigless units. TTBP has proved very reliable in most of the cases however; the success rate has been debatable for highly deviated wells with high-pressure differential across the plug. Eline applications normally struggle at deviations > 60°, because of losing the gravity force driving the tools downward, limitations of tool string length due to dogleg in the angle build up sections. Several through tubing options are now available to overcome these challenges, for example coiled tubing, which requires rig assist for offshore sattelites application, & eline tractoring, which adds more cost to eline job and depends on local availability in the area of operation. TT mechanical shut offs face some challenges more than ability to deploy tools to required depth. Several types of through tubing cement dump bailers are available in the market; however not many jobs were performed in deviations > 70°, there is always a debate about capability of bailer to dump all cement on depth at such deviation where gravity force is minimal. In addition, the effect of cement slumping in higher deviations is another challenge for building a good cement sheeth that guarantees good sheer bond strength and able to withstand required pressure differential. A Challenging example was an offshore horizontal well where the primary target is required to be isolated and the objective is to test a new reservoir in the field which was not tested before in the area. Due to uncertainity in productivity, saturation & fluid type "Oil or gas" of the new characterized reservoir. The operations was intended to be at the minimum possible cost in order to keep the business risk at the lowest level. The target perforation interval was located in the build section of the horizontal well where deviation angle is 74-76 degrees. The existing perforations were flooded out and it was necessary to isolate prior to test of the target reservoir. Isolation using through tubing bridge plug on eline was assessed and different operation risks were evaluated, conveyence to the target depth without an eline tractor was assessed in the planning phase using a tension model. Slickline operation was modified to confirm the validity of the model and we successfully reached the target depth using slickline. During the planning phase, we considered many precautions to guarantee job success. A successful mechanical shut off job in a deviation of 74-76 degree was confirmed by positive test to the plug and the successful production from the well that produced more than 10 MMSCFD & 300 Barrels of condensate per day.

This paper aims to highlight the benefits of using selective perforation as a method of risk reduction and optimization during perforating thin separated oil-bearing intervals going through selection criteria, job design, economic evaluation and precautions during the operation. During the design of four perforation jobs in a campaign using the conventional through tubing perforation (TTP) technique, it was noticed that the number of runs were too much with consequent high intervention risk, thus alternatives were evaluated to mainly reduce intervention risk with a smart, reliable, cost effective and simple perforation technique within the pre-determined operation time frame. The other options included alternative deployment methods such as coiled tubing (CTU) perforation, extended reached perforation (ERP) and selective perforation techniques. A comparison between options has been made based on the following criteria: availability, simplicity, reliability, intervention risk and feasibility. As a result of proper filtration and comparison between all different options, the selective perforation using addressable switches was selected to be the optimum solution for this case based on the comparison criteria mentioned above. Going through the design phase, multible loading sheets for guns laydown have been generated and optimized to reach the simplest operational procedures and minimum number of runs. Then, workshops have been made for engineers in both office and field to be familiar with the operation to reduce operational risks and consolidate the operational procedures. The design of service for the whole job including the final operational procedures, risk assessment and gun loading sheets was finalized and distributed to all disciplines to assure alignment during the operation. During job execution, operation has been followed step by step using single point of accountability (SPA) to accelerate and align decision making and plan modification during operational issues. Finally, a post job evaluation has been made to document the whole procedures of design and execution and the lessons learned during the operations. A final comparison between conventional and actual selective perforation job showed the reduction in number of runs and thus time and intervention risk by 33%. In addition, the incremental increase in cost was completely covered by the time saving from the utilization of supporting vessels (Rig & boats). The major aim of this paper is to clarify in a step-by-step style the method of evaluating the well for addressable switches technique and how to properly prepare the people for the job and the design of service till execution followed by post job evaluation.