Effect of CO2 Gas on the Logging Measurements and the Impact on Porosity Calculations

Summary Gas fluids have a definite impact on the nuclear logging measurements affecting thereon the estimations of the porosity and lithology. To overcome the effect, the hydrocarbon corrections have been designed based on the fluid properties located in the vicinity of the well bore logging area, equations to correct the effect have been supported with laboratory analysis, however the true fluid in the invaded zone is not always clear. The presence of CO2 gas (and contaminants in general) brings into the equation another uncertainty that has not been well documented and till today remains unknown.