Numerical Study on the Gas Leakage and Dispersion at the Street Intersection of a Building Group

Accidents involving natural gas leakage and dispersion pose a significant threat to human life and property.This threat is especially relevant at the street intersection at which dense buildings,heavy traffic flow,and complex underground pipe networks meet.Scholars have conducted numerous studies on gas leakage and dispersion,but investigations of natural gas leakage and dispersion at the street intersection of a building group are not in-depth.In this paper,we presented a three-dimensional(3D)physical model based on the Computational Fluid Dynamic(CFD)methodology to study the natural gas leakage and dispersion at the street intersection of a building group.We validated the CFD methodology applied in the research based on the data from the field tests and wind tunnel experiments.Then,we simulated and analyzed the pressure,wind,and concentration of natural gas dispersion at the street intersection.The simulation results showed that vortex regions,low-pressure zones,and a building group effect could cause a build-up of natural gas concentration under perpendicular wind direction conditions.In addition,the area of hazardous region tended to increase first and then drop with the dispersion height.In the case of this study,the maximum area of hazardous region is 200 m2 located in the height of 55 m,which is the middle plane in the computational domain.The results in the paper can provide scientific references for the safe operation and emergency-management decisions of municipal gas.

Technologies in Discovery and Exploration of Fuling Shale Gas Field, China

Marine shale gas in South China is widely distributed and demonstrates an enriched resource. Compared with the North American commercial shale gas field, the shale formation in South China is featured by old age, multiple stages tectonic movements, and high thermal evolution degree and complex reservoir forming conditions. As a result, the existing theories and technical methods of exploration in North America cannot be simply applied to South China. Since 2007, based on the in-depth study on a large quantity of analytical test data, we have conducted the theory and technology research for the southern marine shale gas, found Wufeng-Longmaxi Group deep water shelf high-quality shale gas critical parameters coupling laws, proposed the “Binary Enrichment” theory for highly evolved marine shale gas in southern complex tectonic zone, and established a zone selection and evaluation criteria, which are based on the quality of shale, for the key of preservation condition, and for the purpose of economy. Taking this as a guide, we selected Longmaxi formation Lower Silurian of Fuling area in southeastern Sichuan Province as the preferred breakthrough field for the shale gas exploration. The Jiaoye 1 well has the daily gas production of 20.3 × 104 m3, which embarked the found of China’s first large-scale business development gas field, the Fuling shale gas field. And we submit the first domestic shale gas proven reserves of 1067.5 × 108 m3. The Fuling shale gas reservoirs are deep water shelf marine high-quality shale, with favorable thickness and even distribution, without dissection in the middle. They are typical self-generation and self-storage shale gas reservoirs. The gas fields have high production gas well;high pressure gas reservoir, good gas components and good exploit results, and there for the Fuling shale gas field is characterized by mid-depth, high pressure, high reservoir pressure, and high quality gas accumulation. Up to March 24, 2014, all of the 101 fracture-gas testing wells have obtained middle and upper shale airflow, with the average single well test production of 32.6 × 104 m3/d. In the exploration and development process, technology series in geological evaluation, horizontal well, drilling, well completion, piecewise fracturing techniques have been gradually formed. It is of great importance to commercially develop the domestic shale gas and promote the restructuring of China’s energy structure.