Advances in Micro Gas Chromatography (GC) FAST TWO MINUTE ANALYSIS OF C1 TO C8 HYDROCARBONS FOR MUD LOGGING APPLICATIONS USING A TEMPERATURE PROGRAMMABLE MICRO GC FUSION —DEBBIE ALCORN, INFICON INTRODUCTION TO MUD LOGGING “Mud logging” refers to the creation of detailed reports of a borehole on a well site during active drilling. Liquid, or “mud”, is used as the drilling fluid to bring gas, formation fluids, and rock cuttings to the surface for analysis. A mud log provides key geographical information, including lithology, rate of penetration, and hydro carbon content. The concentration of C1 to C8 compounds is critical and must be performed on a continuous, 24-7 basis GAS CHROMATOGRAPHY FOR MUD LOGGING Gas chromatography has been used for mud logging since the mid-1950s to characterize reservoir fluid composition. Each reservoir is composed of different amounts of hydrocarbon species. By separating these species, gas chromatography provides reliable and stable hydrocarbon composition measurement on a continuous basis. The reported concentrations are then used to determine the ratios of certain compounds, which help identify zones of producible oil or gas. In this study, C1 to C8 hydrocarbons will be analyzed using gas chromatography. MICRO GC FUSION FEATURES INFICON Micro GC Fusion is a small, transportable GC with microelectromechanical systems (MEMS) technology. FEATURES INCLUDE: n Rapid temperature ramping n MEMS thermal conductivity detector for ppm to percent analysis n Front panel display n Web-based, license free software n Wi-Fi connectivity n On-board hard drive for data storage n Modular configuration EXPERIMENT A two-module GC system was used: n Module A – 8m QBOND, variable volume injector n Module B – 10m PDMS, variable volume injector Two methods were developed: n Isothermal analysis of C1 to C5 within 34 seconds n Temperature programmed analysis of C1 to C8 within two minutes complete cycle time RESULTS C1 TO C8 HYDROCARBONS A temperature programmed method was used to analyze an expanded range of compounds. C1 to C8 compounds were analyzed with a total cycle time of two minutes. With the temperature programmed method, compounds such as ethylene and propylene were also analyzed. RESULTS C1 TO C5 HYDROCARBONS C1 to C5 compounds were analyzed within 34 seconds using the isothermal method. Repeatability was excellent, with Area %RSD values less than 0.6% and Retention Time %RSD values less than 0.1%. CALIBRATION STANDARD – C1 TO C5 COMPOUND AMOUNT (%) 1 nitrogen 99.191 2 methane 0.200 CALIBRATION STANDARD – C1 TO C8 COMPOUND AMOUNT (%) 1 nitrogen 98.054 2 methane 0.5 3 CO 2 0.197 4 ethylene 0.095 5 ethane 0.2 6 propylene 0.103 Module A 55C(15s hold) ➔ 220C(10s hold) 7C/s, 35 psi, 30 ms injection time, Helium carrier gas 3 ethane 0.101 4 propane 0.100 5 iC4 0.102 6 nC4 0.103 7 propane 0.197 8 iC4 0.098 9 nC4 0.098 Module B 75C(9s hold) ➔ 220C(12s hold) 7C/s, 33 psi, 80ms injection time, Helium carrier gas 7 iC5 0.102 8 nC5 0.101 AREA %RSD LAST 10 RUNS RETENTION TIME %RSD 1 nitrogen 0.09 0.037 2 methane 0.57 0.041 3 ethane 0.51 0.049 Module A 55°C, 37 psi, 15 ms injection time, 5 second pump, Helium carrier gas 10 iC5 0.102 11 nC5 0.102 12 nC6 0.12 13 benzene 0.021 14 cyclohexane 0.032 15 nC7 0.01 16 methylcyclohexane 0.01 FUTURE DEVELOPMENT The temperature programmed method will be further optimized for speed and capability. Different column lengths and types, alternative detector, and back flush injectors are being evaluated. CONCLUSION Using isothermal operation, C1 to C5 compounds can be analyzed in less than 34 seconds using Micro GC Fusion with excellent repeatability. 4 propane 0.05 0.000 5 iC4 0.33 0.025 6 nC4 0.46 0.024 7 iC5 0.39 0.000 8 nC5 0.33 0.021 Module B 90°C, 33 psi, 15 ms injection time, 5 second pump, Helium carrier gas 17 toluene 0.011 18 nC8 0.02 Using rapid temperature ramping, C1 to C8 compounds can be analyzed with a two minute cycle time. Additional compounds, such as CO 2 , ethylene, propylene can also be analyzed.