The use of open-hole completions in the design of production wells is a particularly appealing choice for oil companies, since it can ensure huge economic advantage compared to conventional cased-hole completions. Nowadays, most operators are looking for more innovative economical well completion design. Swell packer is one of the technology that widely used in open-hole completion strategy with combination of others completion accessories. Coupling the swell packer with open-hole completion application, it makes multiple zonal pressure isolation in the following open-hole completion possible: bare foot condition, predrilled liner, stand-alone screen, open-hole gravel pack or even open-hole fracturing packing. However, few typical implications associated with open-hole completion which complicated further the well integrity and flow performance monitoring. In 2012, 11 oil producer wells were completed in Field X with open-hole completion and installed with stand-alone screen (SAS), swell packers and double valve float shoes. First oil was achieved in April 2012 with all wells initially producing high oil rate and low water cut. However, towards the end of 2013, some of the wells started to show high water production. Production logging (PL) was conducted at Well #1 to evaluate the flow contribution and water source. It was concluded that the water was coming from the bottom of double valve float shoe. Remedial action was taken by setting a plug for water shut-off and the water rate dropped drastically. In 2015, it was decided to replicate the production/well diagnostic analysis in all open-hole completed wells. Similar results were then observed by production log (PL) and consequently, remedial action was taken accordingly. The production log (PL) interpretation, historical production plot and surface well test results were integrated and provide the required information to determine the forward production strategy in these open-hole completed wells. This paper will share multiple case studies where water source diagnostics have been performed in open-hole completions, as well as lessons learnt and best practices throughout this process.

History matching is one of the paramount steps in reservoir model validation to describe, analyze and mimic the overall behavior of reservoir performance. Performing history matching on highly faulted and multi layered reservoirs is always challenging, especially when the wells are completed with multiple zones either with single selective or dual strings. The history matching complexity is also compounded with uncertainties in production allocation, well history and downhole equipment integrity overtime. It is a common practice for deterministic history matching in reservoir numerical simulation to modify the both static and dynamic model parameters within the subsurface uncertainty window. However, for multi layered reservoirs completed with dual strings, another parameter that is most often get overlooked is the completion string’s leaking phenomenon that tremendously impacting the history matching. The objective of this paper is to introduce dual strings leaking diagnostics methodology from various disciplines’ angles. We demonstrate these dual strings leaking phenomenon impact on history matching. This paper covers dual strings leak diagnostic methodology which includes production logging tool evaluation, well’s production performance and recovery factor analysis. Possible factors that gives rise to the string’s leaks including material corrosion from high CO2 and sand production will also be discussed. We will demonstrate on how the leak phenomenon could be mimicked in the reservoir numerical model. Possible risks on future infill well identification if the leaks phenomenon is not incorporated will be also discussed. The dual strings leaks diagnosis and application in numerical simulation is illustrated on a case study of Field "D", a multilayered sandstone reservoir in Malaysia of almost 3 decades of production. This proven leak identification and reservoir model history matching methodology has been replicated for all the fault blocks across the field. It potentially unlocks more than 100 MMSTB of additional oil recovery by drilling more oil producers and water injectors in future drilling campaigns.

Fault Block M is a reservoir package consisting of three major sand layers, A, B and C, with C being the best sand in terms of reservoir properties and continuity, followed by B and A. Fault Block M was developed with water injection through commingling of eight oil producers and three water injectors. In 2012, five more wells were drilled to improve reservoir recovery. In view of a fresh reservoir understanding, the team embarked on a full scale data acquisition including quarterly pressure survey and production logging campaign in 2015 and 2016 to determine sands layer pressure and flow distribution for both producers and injectors. Based on better reservoir understanding, many replications of low cost water shut-off have been conducted, which resulted in the field achieving its highest daily production since the infill campaign in 2012. The ratio of data acquisition and well intervention costs to revenue gain has proven to be low, a perfect production enhancement solution for the current low oil price scenario. This paper reviews how production logging tool helps in reservoir surveillance and production allocation. While commingling production and injection is cheaper in development sense, commingling sand of difference in quality should be done with great care and strategy. While chasing the barrels, periodic data acquisition is crucial thus shouldn't be neglected to ensure correct understanding of production behaviour and RMP requirement.

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Compositional grading resulting from the gravity segregation in thick reservoirs is a common phenomenon observed especially in volatile oil or gas condensate reservoirs. Same phenomenon is repeatedly encountered for reservoirs with high temperature gradients. It is also not uncommon if compartmentalized reservoirs indicate areal variations in fluid properties. But drastic variation in composition and fluid properties both vertically and laterally in thin to moderate reservoirs where the reservoir seems to be connected based on initial pressure data may denote non-equilibrium conditions. In this study such conditions will be assessed for a Malay basin saturated oil reservoir and the challenges and proposed solutions are presented. The individual available samples from appraisal and early production system (EPS) development wells covering six stacked sands each comprising of four segments are thoroughly analyzed for quality and reliability. The information from fluid samples including finger prints for hydrocarbons and CO2, is integrated with pressure and full PVT data to characterize the fluid in this field. Reconciliation of PVT and well test data was harnessed to achieve to a set of representative samples for each reservoir/segment while considering reasonable compositional grading and rate of bubble point depression. The samples were then scrutinized for reliable experimental data. Various alternatives of non-equilibrium initialization vs. defining multiple equilibrium regions with compositional grading were considered. The pros and cons of each method is discussed in this paper and general hints for selecting appropriate approach is given based on type of reservoir being modeled, the purpose of study and available data. It is shown that a fit-for-purpose approach can be adopted to fulfill the requirements of the FDP while trying to reproduce the reservoir behavior. The role of reservoir management and updating the model regularly as per future performance is emphasized. The non-equilibrium reservoir systems have not been extensively discussed in the industry and limited case studies and corresponding challenges and solutions have been presented. This paper discusses fundamental phenomena encountered in dealing with such systems and presents solutions based on the nature of the problem and project objectives both in theoretical and practical sense and in this regard it is novel.