Research On Gas Well Production Decline Law For Low Permeability Gas Reservoir

With the comprehensive development of low permeability gas reservoir, people realizedthat in order to achieve eiffcient development, lower cost strategy should be taken,Optimization well building process and reduce the construction investment is one of theeffective means. Therefore, following the continuous exploration and development, Suligegas ifeld of Changqing gradually fomed downhole throtting technology as the core of wellbuilding process model which prevent wellhead hydrate formation objectively，however, withthe problem that downhole choke may cause lower production and casing pressure recoverybecause of such factors as the bottom effusion, which is hard to produce with the constantpressure or stable production over a long peirod. The unstable monitoirng flow and casingpressure brought diiffculties to dynamic analysis, it’s an urgent need to further study thetechnology of using this kind of data to dynamic analysis. Among them, how to use this typeof dynamic datea to conduct Arps decline analysis for get reliable result is the main contentof this paperThis article try to find trends and patterns rfom unstable production and casing pressurewith production data preprocessing, in order to overcome instable effection of downhole choke,make the dynamic data applicable to the Arps decline analysis. By the means of researchingdevelopment characteirstics of Sulige gas ifeld, the different stages of alternation relationshipbetween production and time，casing pressure and production, cumulative production and time,instantaneous production and cumulative production to analysis the real change trend andregularity, and then using Arps method to determine the type of gas wells decline and initialdecline rate to calculate development indicators, predict the dynamic, evaluate productivity, soas to achieve the aim of dynamic decline analysis for gas well.Following the production data processing and analysis of81gas wells with downholethrotting technology in the esat of Sulige gas ifeld，drew a conlusion that these wells can befitting with Arps exponential (constant percentage) decline which meet the rule of exponentialdecline.Finally, proposed three dynamic characteirstics of gas well production daily—reducedpressure, reduced daily gas yield and water yield, which can represent production informationthat relfected by huge date in production daily and can be used in productioncapacity quantiifcation analysis, that makes gas well production daily with mathematicalstatistics method is feasible.