Prediction of fluid-flow parameters in a gas-cut mud, 1. A basic computer program for determining the fluid-flow parameters in a gas-cut mud

Reduction of mud density at the surface is a serious problem but it has not received the attention given to effects of density reduction in the annulus due to gas-cut. Gas enters the well bore annulus from drilled gaseous sands, shales, or durings swabbing operations.Mathematical equations and computer programs were developed to predict changes of annular fluid-flow parameters caused by volumetric changes of entrained gas as it is transported to the surface. A computer program for a microcomputer (Appendix A) was used to predict changes in the drilling-fluid density, flow rate, velocity and gas expansion. Data from a Gulf Coast well were used in the analysis and results shown in Appendix B.The computed mud density was 0.36 pounds per gallon less than the measured mud density at the flow line. The difference may be attributed to errors of gas volume measured at the surface.