Correlation of Bottom Hole Sample Data

Abstract

Abstract Laboratory data on bubble point pressures and reservoir volume factors havebeen correlated as functions of solution gas-oil ratio, calculated gas gravityof the pentanes-and-lighter fraction of the entire fluid, differential residualoil gravity, and reservoir temperatures. Introduction Several correlations of crude oil properties have appeared in theliterature. D. L. Katz in 1942 presented five methods of predicting oil shrinkage, thesebeing of decreasing accuracy for decreasing amounts of informationavailable. M. B. Standing in 1947 published three correlations of laboratory flashvaporization data of California crudes. From values of GOR (gas-oil ratio), gasgravity, liquid gravity, and temperature, his correlations will predict bubblepoint pressure, formation volumes of bubble point liquids, and two-phaseformation volumes. Curtis and Brinkley in 1949 presented several correlations. From the gas-oilratio, an approximation of reservoir volume factor and barrels of condensaterecoverable per barrel of reservoir space may be obtained; along with liquidgravity and reservoir temperature, the GOR will allow prediction of bubblepoint pressure. These last correlations seem to be more qualitative thanquantitative. Generally, laboratory bottom hole sample tests furnish information on solutiongas-oil ratios, residual oil gravities, bubble point pressures, viscosities ofoils, liquid shrinkages, and occasionally gas gravities. Each of these data hasits own applications and use in reservoir engineering calculations. Theparticular uses of correlated bottom hole sample data are found inProviding a basis for obtaining estimates of formation crude propertiesin fields where bottom hole sampling is impractical or impossible.Greatly reducing the time in obtaining the desired information.Determining the applicability of the results from various bottom holesamples to particular field problems.Avoiding, in many cases, the uncertainties of sampling by replacing it withan element over which greater control can be exercised.Permitting use of preliminary field data in application of productionprocedures before a bottom hole sample can be obtained and analyzed in thelaboratory.Serving as a check on data which may appear out of line.Estimating for a particular type crude the appropriate equilibriumconstants by working backward from the bubble point pressure.Estimating original or other past history properties of reservoirs thatwere not sampled in the past. T.P. 2931