Benefits of assessing the solids production risk in a north sea reservoir using elastoplastic modelling

摘要

A reliable, non-conservative assessment of the risk of solids production is essential in order to identify the optimal completion strategy. A technique for such an assessment is devleoped in this apper through a geomechanical study of the Everest Complex of the North Sea, involving wells 22/10a-T2 and 22/10a-T6. The process is based on calibrating depth indexed measurements at discrete point using core data. The core samples were selected to be representative of the complete range of porosities and various clay volumes throughout the reservoir. The first step is the construction of the reservoir mechanical model by combining geophysical well logs, the results of laboratory tests on core samples, and other field data, particularly drilling histories. In the second step, critical drawdowns calculated using elastic-brittle modelling are calibrated using predictions determined at single points using an elastoplastic theory (Bradford and Cook) which incorporates the influences of plastic hardening and dilation. Results calculated using a new elastic-perfectly plastic model, which is derived in this paper, are also included. This model is suitable for use with log data. Results have been verifed by simulating production through a perforation with thick wall cylinder tests on whole core from 22/10a-T2 (Nicholson et al.). The results of the modelling provide formation failure data to build a map of the sanding potential in the Everest reservoirs.