Abstract

The Montney formation of northern Alberta is a very low permeability reservoir with regions of liquid-rich gas production. The reservoir is typically developed using multi-stage fracture horizontal wells with multiple wells per pad. The produced gas ultimately flows into a gathering network that may have both high and low pressure systems. The primary objective of this paper is to present an efficient workflow for preparing and utilizing an integrated gas reservoir / network model of a Montney field as a tool to determine the optimum facilities plan for the field. Pipeline infrastructure planning is needed to accommodate the large amount of drilling that will ultimately support future LNG demands. Optimizing the development is critical, especially during times of low commodity prices.

This paper presents a simplified tight gas reservoir modelling workflow, which has proven to be successful in the Montney and other fields. The workflow integrates available technical work on a field into one simplified full-field development planning tool. Basically, for each current and future well, a simple gridded numerical reservoir model is developed that matches the short term flush production and the long term type curve predictions. The wells are then attached to a gathering system model, thus creating a tool for optimization and planning. Type curves alone are not adequate for short term planning because they do not react to changes at the surface.

The implemented workflow has proven to be effective for optimizing development such as the sizing and timing of compression and the scheduling of infill activations. It has also been useful for quantifying back-out of existing production upon infill drilling and ensuring that facilities such as pipelines and compressors are properly sized. The timing and impact of switching rapidly declining wells from high pressure to low pressures systems was also considered when optimizing the system.

The workflow has allowed for full-field shale gas models to be developed with reasonable model construction times and manageable model running times. The workflow could be applied to other similar fields or formations, such as the Horn River in north-eastern British Columbia or the Duvernay in central Alberta.

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