The Importance of Clay Behaviour for Geomechanical Modelling of Gas Production in Unconsolidated Reservoir Sands

Highly unconsolidated reservoirs may give rise to important compaction and subsequent sea bed subsidence are expected during reservoir pore pressure reduction which may have an impact on sub-sea infrastructures, borehole stability and completion integrity of wells. In this paper, 1D and 2D geomechanical analyses were performed to infer the most important parameters for reservoir compaction and assess the impact of parameter uncertainty on compaction and subsidence prognosis. Owing to the complexity of the reservoir architecture, geomechanical modelling is challenging due to; lateral and vertical heterogeneous distribution of sand / clay facies at large scale (reservoir grid cell) and smaller scale, and scaled geomechanical properties of the grid cell; large proportion of clay within the reservoir intervals and potential drainage of the clay during reservoir production.