Volume Estimation of Sour Natural Gas Using Volume Translation Peng-Robinson with Translation Equation as a Function of Molecular Weight and Acentric Factor

Research and development to improve sour natural gas volume estimation accuracy are continuously done to upgrade the industrial sectors. The accurate volume of sour natural gas is necessary for engineering calculation. The most accurate way to obtain the real volume is by performing experiments. However, it is expensive and timeconsuming to obtain sour natural gas volume with a wide variety of compositions and conditions. The volume estimation accuracy can be achieved by applying chemistry and mathematics. Natural gas volume in a specific composition, temperature, and pressure can be estimated by equation of state. Peng-Robinson (PR) equation of state, usually used in the natural gas industry, has some drawbacks in calculating volume accurately. In this paper, Volume Translation Peng-Robinson (VTPR) is applied by adding the translation equation to modified PR in Tr=0.8–1.08 and P=12.38–30.38 MPa based on well P. To simplify the volume estimation for various compounds, translation equations parameters will depend on compound characteristic. Previous researches had formulated translation equations as the function of two compound characteristics which are molecular weight and acentric factor. However, H2S and CO2 have not been involved yet. In this study, three VTPR will be formulated with translation equation as the function of molecular weight, acentric factor, and both to estimate the volume of sour natural gas accurately. Parameters are optimized using regression to get the translation equation so that the calculated volume can approach the real volume. The result is that three VTPR have lower Average Absolute Deviation percentage (%AAD) than PR to estimate pure compound volume in sour natural gas which are 2.07%, 1.05%, and 1.47% respectively. When it is applied to sour natural gas mixture, The %AAD are 0.03618%, 0.00097%, 0.00825%, respectively. It can be concluded that these VTPR could provide accurate sour natural gas volume estimation.