Evaluation Method Of Transmission System Process Design Adaptive High Sour Gas Field Set

In recent years, with the exploitation of China’s high sour gas field of a large area, its difficulty development and high safety and environmental protection requirements put forward very high requirements for high sour gas gathering process design of our country. With some risk assessments of several built pipelines being done, some high risk points come out while the design meets the requirements of the design standards. Also it exposes that the design standards are the minimum standards to ensure the safety even though some corresponding protection measures have been taking for the high risk areas during design stage. The security measures are hard to grasp due to the lack of systematic risk analysis. Therefore, the adaptability evaluation of the design indexes needs to be carried out in the design stage to perfect the design scheme continuously for improving the initial operation safety of the system and avoiding unnecessary and unplanned maintenance and replacement during the operation and maintenance managing process. Based on a lot of literature investigations, this paper studies the method of the adaptability evaluation for the high sour gas field gathering system process design. The main research contents are the following aspects:(1) Based on the literature and field research, this paper summarizes and analyzes the current situation of the pipeline/station integrity management and the integrity management of the high sour gas field gathering and transportation system during the design stage. Also, this paper puts forward an adaptability evaluation of the corresponding process design indexes combined with its design characteristics during the design stage of the high sour gas field gathering and transportation system.(2) This paper defines that the adaptability evaluation method is proper for the design of the high sour gas field gathering and transportation system with its volume percentage of H2S higher than5%which is called high/extra-high H2S containing. And the object of the evaluation is the main process scheme of the gathering and transportation pipeline/station. The main process scheme means the main process involving the conveying medium, especially the corrosion design indexes related to the safety of the sour gas production, the design indexes related to the safety of the pipeline or the important equipment of the station and the external environment indexes.(3) This paper determined the adaptability evaluation method for the process design of the high sour gas field gathering and transportation system with the indexes system evaluation and the two-level evaluation including the key index and the normal index. According to the characteristic of the process design of the pipeline and the station, the index system is divided into two parts for the pipeline and the station, while the station including the gas gathering station and wellsite.Based on the process design characteristic of the pipeline, the gathering station and the wellsite, the relevant standards/specifications and engineering practice, it established the corresponding index system for the adaptability evaluation.(4) This paper choses the improved fuzzy AHP as the weight calculation method for the indexes by using the rank of the index weight given by the technical experts from the CPE Southwest Branch Company and the Matlab program to calculate the weight of each index.(5) The author developed the adaptability evaluation software of the process design for the high sour gas field gathering and transportation system with the platform of Visual Basic6.0.This program can do the adaptability evaluation for the gathering and transportation pipelines, stations and wellsite separately with simple operation and friendly interface. Using the program, it can get the adaptability evaluation score of the process design along with its degree of adaptability and unoptimal indexes.Besides, some corresponding design suggestions can be gived out according to the evaluation results.(6) An adaptability evaluation has been done on the preliminary design of the internal gathering and transportation engineering of the Longgang gas field trial production by using the software. The degree of adaptability of the design of the pipeline between Longgang001-6well and001-7gathering station, the Longgang001-7gathering station and the Longgang2well are high by the evaluation results.It means that the process design indexes of them have good adaptability according to the high sour gas field gathering and transportation system.The results also exposes that some design indexes still could be improved to increase the overall reliability for the design of the gathering and transportation system.