A Study Of Groundwater Environment Impact Assessment For The Natural Gas Production Projects In Daniudi Gas Field

Currently, regional groundwater environmental security issues caused by large-scale gasdevelopment gradually become a hot research and focus. For gas fields adverse impact on theenvironment, in order to ensure the normal and orderly development of natural gas industry, anurgent need for gas field development groundwater environmental impact assessment. Theworking procedures, evaluation content and the methods of evaluation technique contained in"Technical Guidelines for Environmental Impact Assessment-Groundwater Environment"(HJ610-2011) basically apply to gas exploitation projects, but due to the influence ofgroundwater environment caused by gas field exploitation exists some profession characteristics.Therefore, the practical application of the guidelines may be have some problems.In this paper,taking the gas production project of big8-65wells of horizontal well in daniudi gas field as anexample, through the engineering analysis to gas field development projects, the influence of thegroundwater quality and quantity was cleared. By analyzing the impact of the project ongroundwater quality is more prominent. Through the analyses of pollution sources in thedrilling phase, the production operational phase, the decommissioning phase and accident phaseand the environmental impacts on groundwater in those stages, the conclusion is that undernormal circumstances the drilling phase, the production operational phase and thedecommissioning phase will have little effect on groundwater, accident phase will impact thegroundwater environment. Collation and analysis of the study area’s natural geography, geology,hydrogeology, development and utilization of groundwater and other information, clear therelationship between the strata,the aquifers and the development mesh layer. By analyzinggeological and hydrogeological conditions of gas field, the water quality and the water levelwere monitored, and the status evaluation of the water quality and the water level were donebased on the evaluation standard and evaluation method Selected by "guidelines". The evaluationshow that the groundwater quality overall is good but individual points exceed the standard,excessive factors are ammonia, nitrate, nitrite, iron, and level dynamics changes little. Thecorresponding water line are drawn. Pumping test and water penetration test, calculate therequired parameters of the numerical simulation. The hydrogeological conceptual andmathematical model according with practical situation is established with GMS, and is identifiedand verified according to the model parameters obtained.Based on the numerical model, combined with the actual exploitation, Solute transport model forecasts the conditions that themud sewage treatment plants, the methanol sewage treatment plants, the sewage treatment plantsand the treated wastewater reinjection wells under accident conditions which can affectgroundwater environment, and according to predictions combining with guidelines appropriatecontrol measures. are proposed. On this account, the groundwater environmental impactassessment of gas field development provides a scientific basis better for gas constructionprojects’location decisions, engineering and environmental management.