Fast Sampling Field Deployable Mud Gas Carbon Isotope Analyzer

Sheng Wu,Andrew Sneddon,Le Lu,Andrei Deev,Yan Zhuang,Yongchun Tang,Zhengyou Wang

doi:10.3390/geosciences10090350

Abstract

We report the details of a field deployable mud gas carbon isotope analyzer for mud gas analysis based on coupling a gas chromatograph with a mid-infrared spectrometer using a quantum cascade laser and hollow waveguide. The GC–IR2 (gas chromatograph–infrared isotope ratio) system features a fast sampling cycle as short as 123 s for analyzing all three components, i.e., methane, ethane and propane. The samples are automatically diluted so the system could carry out effective measurements while sample concentrations vary from 400 ppm to 100% purity. The accuracy is guaranteed through periodic reference calibration, and variations due to field temperature changes are minimized.

Highlights

Compound specific isotope analysis (CSIA) has profound impact on geological exploration of oil and gas
In 2007, Los Gatos Research introduced the first field deployable CSIA instrument [7] based on a near-IR laser and cavity-enhanced absorption platform, i.e., the off-axis integrated cavity output spectrometer (OA-ICOS) [8], and have been applied by Geoservices in mud logging for almost ten years, with methane isotope analysis only
This implies that a GC system with a flow rate at 12 sccm, and even with the split coupling open to the air, the refresh rate is faster than 12 sccm/13.5 μL, or 15 Hz

Summary

Introduction

Compound specific isotope analysis (CSIA) has profound impact on geological exploration of oil and gas. The advances in optical absorption spectroscopy, in particular the transformational progress in cavity-enhanced absorption spectroscopy in the near infrared (NIR) during the past 24 years, have made such field deployable machines technically feasible. There are still many detailed technical difficulties that slow the progress of a gas chromatograph–infrared isotope ratio (GC–IR2 ) instrument that could conduct precise and fast measurements, and yet be free from interferences. In 2007, Los Gatos Research introduced the first field deployable CSIA instrument [7] based on a near-IR laser and cavity-enhanced absorption platform, i.e., the off-axis integrated cavity output spectrometer (OA-ICOS) [8], and have been applied by Geoservices in mud logging for almost ten years, with methane isotope analysis only.

Methods

Results

Conclusion