Abstract

Gas compression has been widely adopted by the petroleum industry and is validated as a reliable method for improving reserves base. As depletion drive gas fields mature, their reservoir pressure declines with an associated reduction in gas production rates. This phenomenon is even more pronounced in fields where aquifer water breaks through and results in rapidly falling well head pressures which naturally result in reduced reserves recovery over the producing life of the field. Compression at wellhead or at the facility elongates well and field life resulting in tapping additional reserves, which may be left behind in case surface compression facilities are not put in place in a timely and phased manner.

Compression was initiated at Bhit Gas Field from 2009 and implemented in a phased manner over several years. In first phase, well head compression was deployed to ensure a continuous plateau rate and provide additional gas recovery at 100 psig suction pressure which was selected through matching compressor curves against well deliverability. In second phase, booster compressors at selected wellheads were installed to further drop pressures d upto 50 psig. This was followed by optimization where existing compressors were not only swapped, relocated and reconfigured but also spare compression capacity was utilized by merging wellhead to nodal compression to further drop pressures upto 20 psig leading to increased recovery. Surface optimization actions were justified by set of forecasted results from simulation model utilizing compressor curves.

This paper will demonstrate the continuous surface optimization performed as a function of reservoir and well response with the ultimate aim of enhancing reserves recovery by comparing actual field performance with Forecasts from a numerical simulation model. Highlights on the benefits of timely identification and implementation of compression needs achieved through significant cost savings and reduced project time to market will also be presented

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