Prediction of Source Rock Characteristics of Hydrocarbon Gases in the Camurlu Field (South Eastern Turkey) by Isotopic Modeling

Abstract

From six different production wells in the Camurlu Field, which is one of the important production regions in South Eastern Turkey, gas samples were investigated for their molecular and isotopic composition in order to determine origin of gases and probable source rocks. TOC measurements, kerogen isotope analysis and Rock-Eval pyrolysis analyses were also performed using cutting samples taken from three different wells in order to determine the characteristics of probable source rocks and to utilize this data for isotopic modeling. It was specified that kerogen isotope values of these samples varied between \({\delta^{13}}\) C −28.0 and −22.9 ‰. Stable carbon isotope ratios of Camurlu gases were determined as \({\delta^{13}}\) C1: −38.2 to −33.6 ‰, \({\delta^{13}}\) C2: −32.9 to −29.1 ‰, \({\delta^{13}}\) C3: −31.1 to −29.1 ‰, respectively. In the classifications conducted according to methane, ethane and propane \({\delta^{13}}\) C and methane \({\delta{\rm D}}\) isotope values, it was observed that Camurlu gases are thermogenic gases. Isotope modeling was applied in order to determine the characteristics of the probable source rock that generated the thermogenic Camurlu gases. In the isotope modeling according to methane–ethane, ethane–propane isotopes, it was determined that hydrocarbon gases were generated from a single source rock and its maturity varies between 0.8 and 1.0 (%Ro). Organic matter type of the source rock was specified as a mixture of Type II and Type III kerogen. As a result of the assessments made, it was found that the source rock of Camurlu gases can be the Paleozoic source rocks.