Coalbed-methane (CBM) production in the San Juan basin of northwestern New Mexico and southwestern Colorado has spanned more than 30 years. Some parts of the field, such as the high-permeability Fairway, are now in a mature stage of reservoir-pressure depletion. Optimization of well-production operations in the Fairway presents many challenges because of its extremely low reservoir pressure (less than 100 psi in some areas), heavy coal-fines production, difficult artificial-lift challenges, increasing CO 2 %, and the presence of paraffin, inorganic scale, and corrosion.We use history matching by reservoir simulation to help diagnose the causes of well-production inefficiencies and then plan how to mitigate them. Simulation of Fairway wells typically require the use of an increasing reservoir-permeability trend caused by coal-matrix shrinkage with the desorption of methane and CO 2 . However, we have observed in some Fairway wells that below a reservoir pressure of approximately 300 psi, there is a flattening or even a decrease in the permeability trend. This shift in the permeability trend is likely caused by coal failure (i.e., a change in mechanical properties of coal) that is evidenced in the wells by an increased amount of coal-fines production.This paper is written in two parts. The first part presents the challenges we face in operating Fairway wells and the solutions we have developed to overcome them. Field observations and operating guidelines will be shared, along with well-intervention histories where we have seen success. The second part discusses our use of reservoir simulation to diagnose the causes of reduced well-production efficiency.

Coalbed methane (CBM) production in the San Juan Basin of northwestern New Mexico and southwestern Colorado has spanned over 30 years. Some parts of the field, such as the high-permeability Fairway, are now in a mature stage of reservoir pressure depletion. Optimization of well production operations in the Fairway presents many challenges because of its extremely low reservoir pressure (less than 100 psi in some areas), heavy coal fines production, difficult artificial lift challenges, increasing CO 2 %, and the presence of paraffin, inorganic scale and corrosion.We use history matching by reservoir simulation to help diagnose the causes of well production inefficiencies and then plan how to mitigate them. Simulation of Fairway wells typically requires the use of an increasing reservoir permeability trend caused by coal matrix shrinkage with the desorption of methane and CO 2 . However, we have observed in some Fairway wells that below a reservoir pressure of around 300 psi, there is a flattening or even a decrease in the permeability trend. This shift in the permeability trend is likely caused by coal failure (i.e. a change in mechanical properties of coal) that is evidenced in the wells by an increased amount of coal fines production. This paper is written in two parts. The first part presents the challenges we face in operating Fairway wells and the solutions we have developed to overcome them. Field observations and operating guidelines will be shared along with well intervention histories where we have seen success. The second part discusses our use of reservoir simulation to diagnose the causes of reduced well production efficiency.

Completion design is a key factor in maximizing well inflow performance and deliverability throughout the life of a well. During the early stages of development of a green oil field located offshore Abu Dhabi, improved subsurface understanding from data gathering led to the modification of the initial completion design. This paper presents a systematic approach utilizing an integrated workflow to successfully optimize multi-zone horizontal well completions to lower development costs, reduce risks and increased field recovery. The final well architecture was implemented in the Early Production Scheme (EPS) and Full Field Development (FFD) phases of the development. The main achievements of the integrated completions design are: ○Increased well productivity and deliverability.○Optimized completion strategy for low efficient gas lift wells.○Reduced risks in well construction and completion phases.○Improved completion flexibility for life-of-well intervention operations.○Optimized slot allocation to increase recovery with more wells.○Utilized full benefits of conductor sharing technology.○Added flexibility to successfully appraise an undeveloped carbonate reservoir and to incorporate it into the development plan.○Adopted new methodology for lower completion design in multilayer reservoirs.○Considered simultaneous dual system injection and production (SIP) wells. The comprehensive approach presented is valuable in establishing a total life-cycle workflow during the early stage of field development, which can be embedded in any completion design strategy. The completion solutions highlight significant benefits from overcoming well-known challenges in offshore environment such as space limitations, slot availability, and cost optimization. The end product is a life-cycle design identified for each specific reservoir with reduced operational constraints and well intervention complexity.

The ultimate success of an offshore field startup depends on the strategy and integration within an organization. Even more challenging is managing the dynamic interface of subsurface and surface project delivery through the design, construction, hookup, commissioning, and startup operations. This paper presents the case study of a new field startup in Abu Dhabi from the early concept selection through the critical startup phases. Integrated multi-discipline approach underpinned the successful startup when the field achieved first oil production ahead of schedule on February 2015 and exceeded expectation despite the backdrop of global sharp decline in oil price. This paper highlights the technical and functional preparation put in place by the subsurface and surface teams to ensure full integrated readiness and plan-in-place for production start-up. It also outlines the challenges encountered to achieve operational performance and the major lessons learned from the journey. The results demonstrated in this paper shows that an integrated and cooperative approach is key in dealing with delays, prioritization, execution of processes, projects and operations. The lessons learned from subsurface and surface technical preparation, through surface project engineering and delivery phases are presented. Successful management was critical in handling the drilling rigs and barge logistics, offshore installation and commissioning phases, and simultaneous operations during the production start-up and ramp-up of the field. In addition, while encountering pressures to minimize rig time and execute the extensive data gathering program, good team synergy ensured that the milestones were successfully met even with the additional limitation of skilled technical resources. Finally, illustrated in this paper are best practices applicable for new offshore field startups. This proves that even with the financial-demanding outlook and market-down conditions, the successful startup of a new field is essential and visible.

The accurate metering of flow rates across the production chain, from sandface to sales point or custody transfer point is of vital importance. With the use of multiphase flowmeters (MPFMs), measurement of multiphase flow under dynamic conditions is possible. In well tests, the assurance of optimal flowmeter performance is of great importance because test results can significantly impact long-term field development planning and well management. We highlight the integrated approach implemented to improve flowmetering performance for a new oilfield offshore UAE In offshore fields, MPFMs have been installed on production towers to measure production of individual wells. In the first phase of field development, commingled flow from all wells is also metered at the outlet of the manifold tower (MFT) before entering the subsea line to the processing facility. The installed MPFMs eliminate the need for traditional test separators or dedicated test vessels. However, since multiphase flow is complex, turbulent, and chaotic, the acquisition of accurate, reliable, and repeatable rate measurements can be a challenge. Fiscal measurements must also meet statutory requirements for accuracy in hydrocarbon accounting and production allocation. We present the case study of a new field, the initial challenges encountered in achieving quality test data, and the systematic approach established to streamline flowmeter performance. This approach comprises representative fluids description, results validation, and calculation model optimization, which has resulted in improved performance of wellhead and MFT flowmeters. The process of streamlining flowmeter performance verification and optimizing flowmeter utilization to track individual well performance has resulted in cost savings and improved production optimization. Well-specific pressure-volume-temperature (PVT) models have provided optimal conversion of line conditions to standard conditions, with reduced uncertainties introduced by pressure, temperature, and effluent variations. As a consequence, ideal production allocation factors were achieved, yielding confidence in the use of well test data for production and reservoir management purposes. An added benefit is the increased confidence in the data quality for history matching of the dynamic model. Effective production monitoring as new production streams from different reservoirs come on line has enhanced production reconciliation due to reduced uncertainty from commingled flow and improved production forecasting. The principles employed in multiphase flow measurement technology are not new. However, real-time, accurate flow rate measurements are essential for good decision-making, sound engineering analysis, and effective life-of-well management. The application of a case-by-case approach to flowmeter configuration, combined with an efficient monitoring approach, has proved very valuable to achievement of effective reservoir monitoring and well management.