Mari Gas Field; discovered in 1957, is one of the oldest and mature fields of Pakistan and currently the highest gas producing field of the country. Mari Field has vital role in ensuring the food security of Pakistan as it is meeting gas needs of 87% of Fertilizer Industry. Field has been developed in multiple phases with 97 producing wells and complex gas gathering network of 284 km. In recent past few years, the country's supply and demand gap for gas is on widening trend. In order to support national energy needs, MPCL management decided to take initiative of executing gas incremental and optimization drive for playing its part in meeting the crucial energy demand of country. Furtermore, it was also matter of great importance to sustain the enhanced production plateau and meeting production & revenue targets.

Multidisciplinary teams were formed for evaluation of complete system from Reservoir to delivery end. Integrated approach was adopted for assessment of system at existing state of production and targeted production rate as de-coupled models would have not served the purpose well in this particular case. This study covers the integration of sub-surface and surface facilities; linking reservoir simulator at IPR Level, through in-house simulation model developed in commercial simulator. Keeping in view the target of study i.e. incremental and sustained production, reservoir rates were constrained and hence semi-implicit approach was used instead of fully implicit modeling which saved a lot of computation time and avoided complexities. Coupled model was simulated for predicting futuristic behavior of system at enhanced production which identified bottlenecks and integrity problems in existing system and also proposed the solutions through series of sensitivities analysis. This exercise triggered the proactive approach for solving system issues and kicked-off proper surveillance of system which are mandatory to sustain the desired production plateau and ensure the mechanical integrity of system. This study further emphasized that evaluation of complete system through integrated modeling can save compression cost at by de-bottlenecking the existing infrastructure.

At present, the field is producing at 20% incremental volume over and above of initial base volume and future plans have also been formulated to sustain the production plateau as per reservoir simulator.

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