Material balance analysis, a primary engineering technique, is an indispensable tool used for understanding the production performance and field management of mature gas reservoirs. Compilation and analysis of pressure-production data together with acomprehensive geological understanding including in-place hydrocarbon volumes and inter-block communication are prerequisites for material balance analysis. Deviation of observed P/Z data away from a straight idealised line necessitates further study, as it often indicates erroneous estimates of participating in-place volumes, aquifer support or reserves. Lack of pressure measurements, questionable stratigraphic correlations and uncertainty surrounding aquifer propertiesor reservoir connectivity highlight the requirement for further evaluation. The objective of study is to develop a multi-tank material balance modelfor a mature, heterogeneous and compartmentalised carbonate gas field. Ultimately, the model must besufficiently robust to elucidate the field's production mechanism and optimise future field-development opportunities. In this field, the pressure production behavior can be divided into two trends, an early rapid declining pressure trend, followed by a stabilised gradual pressure decline. Owing to higher drawdown in the field's early production life and insufficient recharging, the quick pressure decline underestimates the initial in-place gas volume. This volume is not adequate to support the sustained gas production rates observed in later years. This observation required further detailed analysis regarding the nature of zonal communication across adjacent reservoir intervals to better understand the production behavior of development wells during the design of the material balance model. This paper discusses a study in which material balance analysis is coupled with multi-field network models. Implementation of this workflow can be usedto drive subsurface developmentsin a relatively short period.

Sand Monitoring workflow was introduced in R field to manage and minimize the risk that sand production poses to the production facility by monitoring the sand production and its resulting erosion rate, and raise alarm immediately when these conditions violates the allowable threshold. The workflow serves as an enabler to the sand management process that are put in place at the field. By leveraging the automation from IO and complement it with additional processes, we came up with a holistic approach that is used to minimize the risk to the production facility. The defined Sand Management methodology starts with the automated workflow processing. The workflow utilizes data from field sensors and processes them to conduct risk assessments, and some mathematical calculation that are based on proven correlations. Based on these processes, the workflow will generate output of sand production risk assessment, calculated erosion rate, estimated remaining pipe thickness as a result from the erosion rate and critical drawdown monitoring. To complement the output from the workflow, additional processes that utilizes the outputs are introduced as part of the sand management process. Some of these additional processes are: Correlation calibration by comparing the estimated pipe thickness from the workflow against computerized radiography or unit thickness manual measurement.Conduct Sand Depositional modelling at the high-risk location identified from the workflow to optimize sand handling capacity and monitoring.Extend the monitoring by utilizing network modelling software to assess the erosional risk from interlink of pipelines between jackets.Choke health monitoring and estimation based on choke CV and modelling. The sand monitoring workflow has increased personnel efficiency by automating repetitive and tedious work and give out the result in an easily interpreted manner. The automated alarm has been proven to be useful in proactively engaging operations to tackle the problematic matter. Production interruption related to sand production has been effectively reduced by 50% after the implementation of the new Sand Management methodology. The introduction of the workflow into the new methodology uses marginal cost, but maximizes the return on existing asset through the realization of their production potential, as well as proving on how multidisciplinary integration and collaboration between operator and the service company can be successful in a mature field despite the risk associated.

In a complex offshore gas network covering both green and mature fields' production to LNG plants, end-to-end integration is essential in building a portfolio that can maintain output. Often in the course of identifying conceptual development opportunities by individual field, this aspect isoverlooked in the broader context of regional optimization. To provide assurance of production sustainability to meet commercial agreement, it is imperative to formulate a development plan that integrates subsurface and surface elements to accurately quantify the remaining reserves and thus the value of the asset. As such, this paper will focus on the methodology of formulating this optimized development plan to incorporate subsurface and surface network modeling and demonstrate the importance of this system for excellent asset management and future development. A series of reservoir evaluations has been performed on a simple one-dimensional model and three-dimensional model depicting the gas reservoir performance. The analysis is further enhanced by using subsurface and surface production network modeling. The key advantages of this workflow compared to the conventional field development plan (FDP) approach is that the field capacity is derived based on pressure interface and existing production constraints to capture any backpressure effects for anyinfill drilling or upgrading projects. In this field example, the integrated network model has resulted in a simpler yet more reliable technical proposal where synergistic opportunities and the associated potential production challenges can be identified.Higher level goals on production attainment and cost avoidance can be achieved through circumventing the potential production hiccups for new development. A detailed analysis workflow using real time data will be discussed as part of technical assurance.The key benefits include full field optimization and opportunities identification,and generation ofa representative business case in a timely manner to meet the demands of managing a dynamic gas system.

Critical drawdown pressure for sand onset and its accuracy with change in water cut is a continuous area of study. The numerous parameters like grain cementation, viscosity of fluids, actual physics of sand production with fluids leads to a lot of uncertainty. In practical terms, it has been observed that these mechanisms lead to reduction in Uniaxial Compressive Strength of rocks. The objective of this paper is to present a novel method that not only helps on understanding the effect of water production on sand failure but to further predict the volumetric expected sand production up until a certain tolerable error. A sand prone field within Malaysian region was identified and core tests were done to evaluate UCS and other rock strength parameters at different saturation of water to simulate the effect of water on rock strength. CDP evaluations were done and the values were calibrated with actual field data to have an accurate understanding of CDP values at different water cuts. Lastly, with the findings from field production data, limit was pushed further to develop a novel method to predict the volumetric sand production. The proposed novel method has helped not only in understanding the effect of water production on sand failure but also on the amount of sand to be produced under different drawdown pressures with a reasonable accuracy. These results proved very useful in implementing Company's Holistic Sand Management strategy. The integration of this method with water cut predictions from reservoir simulation models helped the team to quantify the continue increasing sand production due to water cut increase. Company is replicating similar workflow in other sand prone fields for an effective sand management. The approach is very novel as the theoretical modelling work has been effectively calibrated using real field data. This method has provided a high degree of confidence in estimating the amount of sand to be produced under different production conditions. Authors consider this as a breakthrough in field of holistic sand management and very useful workflow for all other operators to emulate.

Well testing is one of the most vital data obtained, which provides numerous information that is related to the well's performance. It is also important to acquire an accurate rate test for reliable allocation and production planning. This paper's objective is to analyze and compare the accuracy of two different types of multiphase flowmeter (MPFM) against a conventional portable test separator. These two types of MPFMs are from two different vendors and each has its own mechanism. A portable testing campaign was initiated with the intention of comparing the MPFMs’ phase rates against those of the separator. The portable testing unit (PTU) was connected downstream to the MPFMs, which were visited pre-campaign by their respective vendors and the required calibration was conducted. A total of 41 wells from various reservoirs and production conditions was evaluated with multirate tests. Overall, the results showed a considerable difference between the phase rates of the traditional test separator and those of the MPFMs regardless of the type where both MPFMs did not meet the minimum requirement of having an acceptable error percentage and only nearly 50% of the tests were within an error range of 10%. One MPFM marginally outperformed the accuracy of the other one. Two problematic regions with high discrepancy between the two metering types were identified either under low-liquid rates or high gas-volume fraction (GVF). Some identified causes will be discussed, which can be of high use by operators who are willing to conduct such comparisons.