Drilling depleted reservoirs can present many challenges from a drilling, completion and production perspective. Formation damage due to increased overbalance for example, is well documented as a particular concern. But could we see some drilling benefit from increased formation damage at higher overbalance?
This paper will outline experience in drilling depleted reservoirs and discuss the impact of formation damage on well productivity, injectivity and drilling performance. In several examples, the benefits of formation damage outweigh the deficits and we propose a planned approach for future wells in depleted reservoirs. Formation damage is measured in the same way as for assessment of the productivity or injectivity impact but the data is applied to a different challenge. The additional pressure drop in the near wellbore area as a result of formation damage can protect the reservoir and minimise fracture propagation. Whilst formation damage can be important in depleted reservoirs it is largely irrelevant if wells cannot be drilled. With the method proposed wells can be planned, drilled, completed and produced (or injected).
The paper proposes better understanding of the impact of formation damage in order to enable drilling, completion and development of depleted reservoirs or intervals and proposes a new methodology to use formation damage as part of a well planning workflow.