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Introduction: Despite low mortality, cardiac surgery patients may experience serious life-threatening post-operative complications, often due to extracorporeal circulation and reperfusion. Miniaturised cardiopulmonary bypass (minimally invasive extracorporeal circulation) has been developed aiming to reduce the risk of post-operative complications arising with conventional extracorporeal circulation. Methods: The COMICS trial is a multi-centre, international, two-group parallel randomised controlled trial testing whether type II, III or IV minimally invasive extracorporeal circulation is effective and cost-effective compared to conventional extracorporeal circulation in patients undergoing elective or urgent coronary artery bypass grafting, aortic valve replacement or coronary artery bypass grafting + aortic valve replacement. Randomisation (1:1 ratio) is concealed and stratified by centre and surgical procedure. The primary outcome is a composite of 12 serious complications, objectively defined or adjudicated, 30 days after surgery. Secondary outcomes (at 30 days) include other serious adverse events (primary safety outcome), use of blood products, length of intensive care and hospital stay and generic health status (also at 90 days). Status of the trial: Two centres started recruiting on 08 May 2018; 10 are currently recruiting and 603 patients have been randomised (11 May 2020). The recruitment rate from 01 April 2019 to 31 March 2020 was 40-50 patients/month. About 80% have had coronary artery bypass grafting only. Adherence to allocation is good. Conclusions: The trial is feasible but criteria for progressing to a full trial were not met on time. The Trial Steering and Data Monitoring Committees have recommended that the trial should currently continue.

North Kuwait Conformance Control task force team initiated to control the uniformity of the flood front of the injected drive fluid during an oil recovery flooding operations, which helps to reduce unwanted water production, enhance recovery efficiency, and to satisfy the reservoir management and environmental objectives. In addition, it will delay pre-mature water breakthrough at the producers on short term and maximize the water flood recovery on long term. Initiatives & new approaches made by field development NK to improve the water cycling and poor sweep occurred as a flood matures with time, which considered as one of the key challenges to control the water production increase. Production/injection philosophy was redeveloped to add further strengthen our ongoing water flood performance improvement integrated efforts. Tackling the high water cut wells, drilling efforts to horizontal sidetracks, and workover of vertical wells conform to the new waterflood strategy have been taken up as ongoing efforts. In addition, some runs made using MA dynamic model to generate prediction scenarios to investigate the response of MA conformance control. The runs showed a positive impact which improve the oil recovery & reduce the water production subsequently. Most of the key producers showed an excellent response as a result of water conformance control application. Many successful cases were observed which have been resulted in water cut reduction and oil production increase. Continues monitoring and follow up is required to achieve the desired well rates so as to reduce cycling of the injected fluid while maintaining or even increasing oil production. Water and oil production responses are under a continuos monitoring as well as injection analysis and reservoir pressure response.

Reservoir souring is the in-situ generation of H2S in the reservoir itself due to waterflood operations using seawater. Some degree of reservoir souring is expected, as seawater is being injected into traditionally sweet reservoir like Mauddud. Thus, a close monitoring was required to track reservoir souring on continuous basis. One of Mauddud wells showed up H2S as first indication of reservoir souring, which was an alarm bell for production facilities designed for only sweet crude. Surface/ Bottomhole fluid samples were required to confirm whether it is localized or reservoir-wide. In order to track reservoir souring and monitor on continuous basis, a process for tracking of reservoir souring periodically was developed and initiated for the first time in 2006. Subsequently, this has been made part & parcel of fluid study requirements each year. Water flooded reservoirs in North Kuwait has been monitored and tracked in regular basis to know the souring level in the reservoir. In light of long term HSE & facility compatibility threat, a special focus was provided by initiating a task force in 2006 to track and timely tackle the issue and create a standard work flow process. All tools available in the industry for sampling, chemical dosage, H2S Measurement methods & prevention aspects with the best industry practices were comprehensively encapsulated. As of 2014, the average H2S level in Mauddud has been managed to be stabilized in an average of (10-20 PPM in gas phase) by effective containment & prevention via the adoption of the work flow process developed. In addition, improved procedure for souring sampling management was implemented for the first time in North Kuwait to capture the bottom hole samples during static as well as dynamic periods of water flooding. Expected H2S levels being very low (10-100 ppm), risk of losing and not capturing these concentrations using conventional samplers/ bottles due to absorption/ reaction with the metallurgy of the samplers was felt, thus posing a challenge for obtaining a representative bottomhole samples for the analysis of H2S. A comprehensive sampling program was made, using the non-reactive internally coated samplers for capturing bottom hole samples; performing the onsite analysis, followed by immediate shipment to the local fluid analysis laboratory and conduct all necessary analysis with expert supervision & care. As per the recommendations based on the sample analysis, water injection wells were treated for the first time in KOC with a biocide to inhibit the growth of SRB and reduce the microbial induced corrosion inside the wellbore. The combination of laboratory tests, various chemical doses and operational practices were defined and integrated with the injection water management teams. The alerts on H2S levels due to reservoir souring has been deemed as one of the best practices while progressing ahead with water flooding giant reservoirs in North Kuwait with sea water, till alternative injection fluids such as Effluent water from GCs or formation water from aquifers or options such as Nitrate treatments are adopted. Value was added to North Kuwait Water flood management by timely knowing the onset of reservoir souring through a comprehensive work flow process built and implemented to contain the threat with periodic tracking/ evaluation and accordingly tackling with tangible actions.

Understanding the fluid flow in the reservoir is one of the main factors affecting the success of waterflood projects. The level of reservoir heterogeneity and complexity of the structure are the main challenge factors to understand the fluid movement. Interwell water tracers is a significant approach especially in reservoirs that have high level of complexity to have better understanding of the injected water flow directions, flow units and reservoir geology. Raudhatain-Mauddud reservoir is highly heterogeneous layered reservoir, bearing different oil qualities. The waterflood started in year 2000 and within a short period the oil rate has increased significantly but with rapid increase in the water cut. The management of Mauddud waterflood project became more complex with increasing the number of injectors and establishing injection in all layers. Interwell Tracers have been utilized to understand the complex injected water movement in the reservoir to improve waterflood management process. Different conservative water tracers have been injected to track the injected water movement between the wells. Tracer breakthrough has been detected in many producers with wide range of tracer's residence time between the wells. Performance of tracer concentration in the stream of each well versus time has proven the flow through different flow units. The Tracer information has been utilized qualitatively and quantitatively to understand the fluid movement laterally and vertically between the flow units and provided invaluable information that has been used for optimizing Mauddud reservoir waterflood, calculating the swept volume and to optimize wells production. This paper presents a detailed review of case history for utilizing the Interwell Water Tracer information to understand the fluid flow in the reservoir and the approach to manage Waterflood operations and optimizing wells` production.

The effectiveness of stimulation using hydrochloric acid in high permeability, fractured carbonate reservoir is a challenge due to several reasons like fast acid spending rates, high leak off and non-effective diversion. All these limit the success rate of matrix stimulation using hydrochloric acid. Ultimately the communication between reservoir and wellbore will be less optimum leading to less than expected well performance. The industry is in continuous search of an effective stimulation technique through which good communication between reservoir and wellbore can be established. In the pursuit of maximizing oil production, Kuwait Oil Company is implementing various new technologies. Recently, acid tunneling technology was piloted in an old producer well in one of its prolific yet challenging Mauddud carbonate reservoir. Acid tunneling is a new approach of stimulation that supersedes normal matrix stimulation in carbonate reservoirs to enhance reservoir contact by creating tunnels through dissolution of rock in acid. Mauddud is a super-giant depletion-drive oil reservoir in NK field undergoing massive development efforts with enhancement in oil production through phased pattern-water flood. The reservoir has 10 layers and the average permeability of the reservoir ranges between 15 md to 1D predominantly due to fractures and vugs, which are distributed and extended variedly from layer to the other. The acid tunneling pilot was performed in an old well in Mauddud limestone located in south-eastern part of Raudhatain field where the rock quality is poor compared to the crestal area. The well was selected for pilot due to poor production. The well does not enjoy injection support due to a sealing fault between it and an injector, lying a kilometer away. The well penetrated three layers A, B and C in Mauddud. Two tunnels of 25 ft each were created using 15% HCl acid. The well showed good production after acid tunneling job and the productivity index of the well increased three times. The well is still showing good performance even after one year. These pilot results lead to full scale field implementation of this technology. The paper presents a case study describing advantages of acid tunneling, well selection criteria for this technology application, selection of effective acid concentration for the job and also limitations of the technology. All these informations work as a guideline to implement this technology in mass scale.

RAMA-Pilot1 is a Mauddud open-hole well which is located in Raudhatain field-North Kuwait. The well had a barefoot completion and it was producing on ESP. Due to low rock quality, the well was performing less than expected levels.It was selected as an acid tunneling pilot for this project to create tunnels and new pathways inside the open-hole section. This is to increase reservoir contact, improve well productivity & eventually increase the near wellbore deliverability. Two tunnels were created successfully inside the open-hole section and the results indicated that the productivity index increased by 3 times from 1.3 to 3.87 bpd/Psi. This successful job was also possible from the lessons learnt, from an earlier attempt of acid tunneling in an Effluent Water Disposal (EWD) well. The job was not successful, and subsequent failure analysis of the job showed an "undersize tool in an oversize hole". So this time sufficient care was taken to measure the hole size properly to size off the acid tunnel tool accordingly. RAMA-Pilot1 success had not only lead to restore & increase wellproduction, but it would also pave the way to enhance oil production and opening up possibilities for field wide applications especially in low PI carbonate reservoir wells. Also, it is considered for improving EWD wells performance by this technique. RAMA-Pilot1 is the first "dendritic" well with extensive wormholes created by acid tunneling for maximum reservoir contact. The whole effect is aptly demonstrated by the change in PI of thewell before and after the acid tunneling as mentioned before. This technique can be planned for any type of wells (EWD, oilwell, water injector) provided there is an open hole and tunnel that is created will be stable. Econimically, acid tunneling technique compares favorably with alternative stimulation options in both time and money savings.

Front-tracking and monitoring of pattern water-flooding are crucial reservoir management activities in the Mauddud (MA) carbonate reservoir. This depletion drive reservoir has been on water flooding since 2000. To help understand the complex water movement that has been observed following implementation of the water floods, it is essential that water tracers be employed in MA injection wells. The use of tracer technology is becoming increasingly important to the petroleum industry and it has proven to be an efficient tool to investigate reservoir flow performance and reservoir properties that are controlling fluid displacement processes. Inter-well tracer has proven to be successful in identifying direct communication between the injection and production wells, flow patterns within the reservoir, thief zones, swept pore volume, reservoir layering, and flood performance. Tracer studies have also been used to complement the information provided by other reservoir characterization methods such as pulse and interference testing. Water tracers were employed in MA since 2007 at a pilot level, which is gradually expanding to full-scale implementation. Monitoring tracer breakthough information have provided invaluable information concerning the influence of faulting and stratigraphy on fluid migration within the reservoir which has been used to guide calibration/updating MA model and planning more tracer projects. The tracer data have been used to reduce the uncertainty attributed to well-to-well communications, and vertical and horizontal flow barriers. The study presented in this paper includes two injection wells which have been on waterflood since 2000. Different water tracers were injected in this field since 2007. Produced water samples were collected for tracer detection. This paper includes discussions on the implementation of tracers in a carbonate reservoir presenting detailed analysis and interpretation of the results.

Raudhatain-Mauddud, a super-giant depletion-drive oil reservoir in North-Kuwait, is undergoing massive development efforts, with a planned enhancement in oil production through phased pattern-waterflood. The Phase1-development covers the crestal-area of the structure, which is the focus for current development efforts through 8 inverted 9-spot patterns. This poster outlines the successful integration of a lot of team's collaboration to significantly improve the operating procedure for water flooding. This effort required a new way of managing this reservoir: a comprehensive approach of balancing voidage with injection, conducting extensive surveillance/analysis to assess the efficacy of various courses of action and, most significantly, adjusting various teams' "key performance indicators" to align injection and production allowable with sound reservoir management principles. An innovative unified information management system was used to monitor voidage replacement ratio (VRR) to provide a basis for pattern balancing. A very extensive surveillance operation provides the data necessary to monitor individual pattern balance and water cut performance, optimizes areal sweep efficiency by adjusting injection and production allowable, assist in planning water-shutoff operations, and design new completions. Time lapsed monitoring and the surveillance data indicates the reservoir is relatively well connected. However, after applying the new management approach, individual waterflood pattern balance is significantly improved and the field-wide VRR is around 1.2. All of these activities have led to the enhanced understanding of the waterflood behavior and the model updates. Sound reservoir surveillance and waterflood management procedures implemented within a diverse group of teams that have performance goals aligned with "best practice" has resulted in effectively re-balancing this major waterflood.