The Development of a Low-Cost Method for Monitoring Methane Leakage from the Subsurface of Natural Gas Fields

The leakage of methane from the subsurface on the coalfield or natural gas field invariably becomes an important issue nowadays. In notable addition, materials such as activated carbon, zeolites, and Porapak have been successfully identified as adsorbents. Those adsorbents could adsorb methane at atmospheric pressure and room temperature. Therefore, in this scholarly study, a new method using adsorbents to detect points of methane leakage that can cover a wide-scale area was developed. In the beginning, the most capable adsorbent should be determined by quantifying adsorbed methane amount. Furthermore, checking the possibility of adsorption in the column diffusion and desorption method of adsorbents is equally necessary. The most capable adsorbent was activated carbon (AC), which can adsorb 1.187 × 10−3 mg-CH4/g-AC. Hereinafter, activated carbon successfully can adsorb methane through column diffusion, which simulates the situation of on-site measurement. The specific amount of adsorbed methane when the initial concentrations of CH4 in a bag were 200 ppm, 100 ppm, and 50 ppm was found to be 0.818 × 10−3 mg-CH4/g-AC, 0.397 × 10−3 mg-CH4/g-AC, 0.161 × 10−3 mg-CH4/g-AC, respectively. Desorption of activated carbon analysis shows that methane concentration increases during an hour in the temperature bath under 80 °C. In conclusion, soil methane leakage points can be detected using activated carbon by identifying the observed methane concentration increase.

Experimental Investigation On Hydrate Dissociation in Near-Wellbore Region Caused By Invasion of Drilling Fluid: Ultrasonic Measurement and Analysis

As we all know, development and utilization of clean energy is the only way for society to achieve sustainable development. Although natural gas hydrates is a new type of clean energy, uncontrollable hydrate dissociation and accompanying methane leakage in drilling operation threaten drilling safety and marine environment. However, dissociation range of natural gas hydrates around wellbore can't be reasonably and clearly determined in previous investigations, which may lead to the inaccurate estimation of borehole collapse and methane leakage. Then, the marine environment will be greatly damaged or affected. The purpose of the present work is to experimentally explore the dissociation characteristics of natural gas hydrates around wellbore in drilling operation, and analyze the influence law and mechanism of various factors on hydrate dissociation. It is expected to provide reference for exploring effective engineering measures to avoid the uncontrolled hydrate dissociation, borehole collapse and accompanying methane leakage. The experimental results demonstrate that acoustic velocity of hydrate-bearing sediment can be accurately expressed as quadratic polynomial of hydrate saturation, which is the theoretical basis for determination of hydrate saturation in subsequent experiments. Owing to the fact that hydrate dissociation is an endothermic reaction, hydrate dissociation gradually slows down in experiment. Throughout the experiment, the maximum dissociation rate at the beginning of the experiment is 8.69 times that at the end of the experiment. In addition, sensitivity analysis found that the increase of stabilizer concentration in drilling fluid can inhibit hydrate dissociation more than the increase in hydrate saturation. Hydrate dissociation was completely inhibited when the concentration of soybean lecithin exceeds 0.60wt%, but hydrate dissociation definitely occurs in the near-wellbore region no matter what hydrate saturation is. In this way, based on the requirements of drilling safety and environment protection, hydrate dissociation and accompanying methane leakage can be controlled by designing and adjusting the stabilizer concentration in drilling fluid.

In-situ marine gas hydrate production methane leaks electrical monitoring system

In the process of gas hydrate exploitation, methane leakage needs to be monitored in real time, so an in-situ electrical monitoring system for methane leakage is designed. The monitoring system is mainly composed of monitoring cable, acquisition station, power module and general control platform. According to the electrical principle, the system carries out regional monitoring on the seabed formation, forms the resistivity map, and realizes methane leakage monitoring. The cost of the monitoring system is low, and it can be remotely controlled or automatically collected data according to the preset program, so the system has good application and research value.

Well-to-Wheel analysis of natural gas for hybrid electric truck application

Compressed natural gas as an alternative fuel obviously has a great potential to reduce the greenhouse gas emissions. Although several studies on the life cycle are quite comprehensive for passenger vehicles, it is problematic to apply these results to heavy-duty electric hybrid trucks. This paper describes the Well-to-Wheel methodology for environmental impact from the gas production to its final application. The CO2 equivalent emissions and the methane leakage point will be identified at the end. The results indicate that compressed natural gas-based trucks have 18.7% less CO2 equivalent emissions than diesel-based ones. However, this benefit may be affected by methane leakage, particularly, in the recovery phase. Reducing methane emissions upstream could be an opportunity to optimize the pollution performance of heavy hybrid electric trucks.