Abstract

Fluid flow through oil and gas reservoirs can induce movement of parts of the rock within and through the pore network. This movement or "fines migration" can have a significant impact on well and reservoir performance. Laboratory testing and detailed mineralogical study can help with quantification and qualification of the potential for and impact of fines migration. Laboratory core flood testing can be used to try to predict the potential for fines migration in any fluid phase and at any velocity. The design of the tests and the limitations of such testing need to be considered before data is too rigidly employed. Ideally, tests should be conducted with the same fluids as will be present in the reservoir, under the same temperature and pressure conditions (including consideration of depletion) and the flow rates carefully selected to replicate reservoir velocities. If tests are conducted carefully then various conclusions on the impact of fines migration on well and reservoir behaviour can be drawn. Several new cases will be presented that demonstrate the potential use of good data and the danger in badly designed tests.

Definition of the size, shape and composition of mobile fines is important in order to understand the potential impact of the fines. Quantification of potential mobile fines is useful but data must be carefully analysed. High fines content is an indication of potential fines migration damage risk but is by no means a definitive predictor. Instead, mineralogical identification needs to be coupled with physical flow testing in order to identify the risk.

If good quality data is acquired the risk of fines migration damage or excessive fines production can be identified and in some cases, appropriate mitigation against fines migration can be adopted. Several cases from oil and gas production wells and water injection wells will be used to illustrate best practice and identify the consequences of inadequate testing.

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