Entropy weight method and analytic hierarchy process for evaluating the development effect in carbonate gas reservoirs,Sichuan Basin
For various gas reservoirs,the development effect is not all the same due to many factors.Especially for the carbonate gas ones in Sichuan Basin,the evaluation is mainly emphasizing on some reserve,development and economic indexes according to existing assessment standards.There are few tools available for fully taking the weight of multiple indexes into consideration,and also less practical standards.Most are common-used industrial or data normalization standards.Instead,an evaluation benchmark that ought to change with evaluated samples may describe their essential characteristics more accurately.Therefore,taken 55 represen-tative gas reservoirs of the Lower Cambrian Longwangmiao Formation in Moxi area(so-called Longwangmiao gas reservoirs)as ex-amples,some ways for evaluating their development effect were discussed.Results show that(i)evaluation indexes may be screened out via the first way of principal component analysis to establish an index system suitable for this evaluation.A total of 11 indexes are involved,including internal rate of return,full cost per unit,investment in production capacity of one hundred million cubic meters,net present value,producing rate of reserves,well-controlled reserves,calibrated recovery,gas recovery rate,degree of reserve re-covery at the end of stable production phase,stable producing life,and reducing rate in the production-decline stage;(ii)integrating entropy weight method with analytic hierarchy process,the second mathematical way may be employed to analyze the weight controls of each index on the development effect quantitatively and qualitatively.The top three on the list are internal rate of return,well-con-trolled reserves and net present value.In other words,these three ones exert the most remarkable influence on the development effect;and(iii)the third way of cluster analysis is used to define the quantitative criteria for index scoring.As a result,a new methodology for the effect evaluation is created for the carbonate gas reservoirs in the basin.After its application to the gas reservoirs,the evaluated findings are in well agreement with actual development.This innovation not only can be used for the effect evaluation in the middle and late development stages,but figure out controls on the effect difference through index comparison.It provides technical reference for all sorts of gas reservoirs to formulate and implement development schemes.
Carbonate gas reservoirEvaluation index systemEffect evaluationEntropy weight methodAnalytic hierarchy process
万方数据
维普
