Inflow Predictions and testing while underbalanced drilling

摘要

With increased interest in underbalanced drilling, including coiled tubing drilling, the importance of realistic inflow predictions and the potential for formation evaluation based on rate measurements is also receiving increased attention. This paper addresses these points by introducing new models for inflow predictions at various levels of complexity and accuracy for spreadsheet and calculator applications. The methods can handle both homogeneous and layered reservoirs, and essentially traps the expected formation response within a narrow range based on drilling speed and the ratio of vertical to horizontal permeability.