Research On Design And Effect Evaluation Of Pressurization Scheme In Yulin Gas Field

Yulin Gas Field is a "low permeability, low pressure, low yield, low abundance" gas field which locates in the Ordos Basin. The gas reservoir type is complex,and the reduction speed of pressure is fast.So it is difficult to develop. Since Yulin Gas Field start rolling development in2001,the gas well pressure reduces rapidly with the extension of development time. It will be not able to meet the pressure requirements of gathering pipe network. In order to ensure the improvement of recovery rate and the economic development of gas fields, the technology transformation must be done on the surface gathering system. In this paper, based on some successful experience relating to transformation of gathering systems, a comprehensive study has been conducted on the pressurization technology solutions and evaluation technologies of Yulin Gas Field. The main research works and related results are as follows:(1)The pressurization technology level of domestic and foreign gasfield and the current research status on relevant theories are summarized. The process and characteristics of pressurized system in several domestic gas fields have been analyzed.(2)By analyzing the current developing situation of Yulin Gas Field, multiple pressurization programs are put forward, such as gas-gathering-station pressurization, central pressurization, regional pressurization and combined pressurization. The features, the site of booster stations and the pressure range of gathering network are introduced. Some important economic technical parameters of each programs, like pressurizing scale, network’s pressure, compressor’s operational states, remoulding pipelines and investment cost, are calculated.(3)The concept and features of pressurization program effect evaluation are defined.By comparing the basic principles, procedures, advantages, disadvantages and scope of some modern comprehensive evaluation methods, including AHP, fuzzy comprehensive evaluation, artificial neural network evaluation, gray comprehensive evaluation and data envelopment analysis, we preferred the fuzzy comprehensive evaluation as the basic method to evaluate the effect of pressurization program.(4)The evaluation index system and evaluation guidelines, consisting by technical level, economic level, security level and environmental protection level,are constructed. Utilizing AHP to determine the weights within the index system. And a fuzzy comprehensive evaluation model of gas pressurization program has been built.(5)Based on C#, a programming language in Microsoft Visual Studio2010,the "Gas Pressurization Program Effect Evaluation Software"has been developed.Some functions, including index system edition, weight calculation, fuzzy evaluation and; data storage,have been achieved.This is a simple, user-friendly and versatile software.(6)A fuzzy comprehensive evaluation has been conducted in the five Yulin-Gas-Field alternatives by using the developed software. The calculation results of Weighted Average Method (WAM) about the five alternatives show that the regional pressurization alternative is the best program. According to "the principle of maximum proximity", we can judge that the alternative belongs to the "excellent" level in the fuzzy comprehensive evaluation system.