Technology Study Of Safety Evaluation And Risk Precaution In Petroleum & Natural Gas Initial Processing System

Natural Gas Company of Daqing Oilfield Limited Company, as national oil dissolved natural gas processing base, mainly takes charge of associated natural gas initial processing, crude oil stabilization, natural gas liquids and natural gas gathering, storage, purification, transportation, distribution by pipelines. Many insecure elements exists in such a petroleum & natural gas initial processing system for its essential characters and factors of personals, equipment, management, circumstance and many others. The safety issues in production is becoming more and more important with the existence of combustible, explosive and toxic materials and the trend to higher temperature, higher pressure, larger scale in petroleum and chemical Industry. To secure safety operation of the company, a safety evaluation method in light of China's national conditions to petroleum & natural gas initial processing system is build based on the successful experience from foreign countries and combining with company's operation realities, which could offer operation management technical directions and provide helpful references for building safety evaluation system and drawing up emergency response plans of petroleum & natural gas initial processing enterprises.This paper studied technologies of safety evaluation and risk precaution, briefed technological processes and chemicals in petroleum & natural gas initial processing system identified and detailed dangerous factors in operations of every processing plants and pipeline network. Meanwhile, this paper introduced some advanced safety evaluation methods adopted home and abroad, including grading-criterion-improved Safety Check List method, classical Dow Fire & Explosion Index Method.Complying with nation's laws, regulations, related active standard specifications, making application research after combination with the real conditions of petroleum & natural gas initial processing system in Daqing, contraposing characters of processing plants and technical process, this paper conducted analysis of current operation of petroleum & natural gas initial processing system, conducted technology research for identifying major hazardous installations, conducted technology research for risk evaluation, conducted technology research for accidents precaution and risk control, conducted technology research for consequence simulation analysis of great accidents, developed a system of safety evaluation and risk precaution for petroleum & natural gas initial processing system, established qualitative and quantitative analysis method in production plants and distribution & transportation system, built a set of risk evaluation technology system of hazardous factor identification, qualitative and quantitative risk evaluation in dynamic and static state of petroleum & natural gas initial processing system, risk early-warning, risk pre-control. The research comprehensively considers the influence from factors of static risk, dynamic risk, management and circumstances, and can give evaluation results matching the present situation of production operation and management technology of petroleum & natural gas initial processing system, corresponding early-warming and control measures.First, after a comprehensive consideration of many factors including materials, processes, equipment, circumstances and management, we determined methods to identify major hazardous source and identified major hazardous sources in the system. We comprehensively used qualitative method (Safety Check List), semi-quantitative method (KENT method), quantitative method (index-number method) and dynamic variables evaluation method to formulate hazardous factors comprehensive evaluation method, KENT method, dangerous degree methods for production plants, pipeline network, valve rooms and Rating Scale method for single equipment. We established risk evaluation model and corresponding evaluation criterion for petroleum & natural gas initial processing system.In hazardous factors comprehensive evaluation method, we take quantity index of major hazardous materials in a unit as a base and modify this index by other indexes including processes, equipment, plant buildings, safety devices and circumstances to calculate the risk index of this unit. We take average risk index of units with higher risk index in this plant as the risk index of this plant to determine the inherent danger degree of this plant. Meanwhile, we also evaluate safety management in the plant and give its safety management degree. This method has a consideration of overall factors, gives an evaluation results matching present operation situation, is easy to grasp and handle.In Kent method (also known as Expert Score Technique), we divide pipeline into sections, score factors to cause section failure point by point (third part destroy, corrosion, design fault, improper operation), calculate the sum of the scores, combine leak impact index of sections and generate a relative risk index to show risk degree of sections. The larger the number of risk degree, the less dangerous the section is. The smaller the number of risk degree, the more dangerous the section is. Since this method comprehensively considers pipe's real dangerous factors and gathers volumes of tactical data and experience from operator, it can give a convulsion with high reliability. This method works well for pipeline network evaluation.We use Rating Scale method to evaluate single equipment. We rate and score evaluated equipment according its service life, served years, types and reasons of accidents occurred, resulted consequence, influenced degree, influenced range and occurred probability of accidents, and difficulty to prevent these accidents, and calculated the accident level of this equipment by multiplying these scores.In dynamic variables evaluation method, we considers time dependent character of operation and management in petroleum & natural gas initial processing system, modify results from static evaluation with three aspects of general operating condition, exceptional operating condition and failure or abnormal condition. We can get a real time risk state of production plants and pipe networks by combining results from static evaluation and dynamic evaluation.We established consequence simulation model for great accidents including leaking & diffusing, pool fire, jet fire, fireball, vapor cloud explosion. With established models, we can calculate possible results, radius of light injury, radius of serious injury and radius of death caused when accidents accrue.Third, we judge the evaluation results to decide accept it or not and take suitable measures to control and manage risks. For production plants, we take two typical plants as investigated subjects, that is, Nanba Oil Stabilization Plant and Xingjiu Light Refrigeration NGL Recovery Plant. For storage and transportation system, we take one transportation team as investigated subject, that is, No. 2 gas transportation team of No. 2 Storage and Transportation Group. On the base of analysis and theoretic calculation of available plants and pipe networks, we put forward qualitative and quantitative methods to evaluate plants and pipe networks, analyzed and optimized given methods, and analyzed and compared the qualitative and quantitative evaluation results.The last, on the basis of evaluation technology research, we used software engineering method in Windows environment, developed risk evaluation software for petroleum & natural gas initial processing system, established platform of risk evaluation for petroleum & natural gas initial processing system on B/S model with software of Microsoft Visual Studio .Net 2005 and SQL server 2005, built a networked safety management information library. This platform can realize many functions including networked safety information management, basic data acquiring, major hazardous source identification and consequence simulation of great accidents.Safety and risk evaluation is an effective method of enterprise's safety management. Foreign countries have acquired some successful experience in this field after decades of research and gained giant economic and social benefits. Thus, the technology development of safety evaluation and risk precaution will undoubtedly have a profound effect on the development of modern enterprise.