中南大学学报(英文版)
中南大學學報(英文版)
중남대학학보(영문판)
JOURNAL OF CENTRAL SOUTH UNIVERSITY OF TECHNOLOGY(ENGLISH EDITION)
2015年
9期
3521-3535
,共15页
王玉玺%刘波%高计县%张学丰%李顺利%刘建强%田泽普
王玉璽%劉波%高計縣%張學豐%李順利%劉建彊%田澤普
왕옥새%류파%고계현%장학봉%리순리%류건강%전택보
carbonate microfacies%quantitative recognition%bayes stepwise discrimination%backward propagation%neural network%particle swarm optimizer
Though traditional methods could recognize some facies, e.g. lagoon facies, backshoal facies and foreshoal facies, they couldn’t recognize reef facies and shoal facies well. To solve this problem, back propagation neural network (BP-ANN) and an improved BP-ANN with better stability and suitability, optimized by a particle swarm optimizer (PSO) algorithm (PSO-BP-ANN) were proposed to solve the microfacies’ auto discrimination of M formation from the R oil field in Iraq. Fourteen wells with complete core, borehole and log data were chosen as the standard wells and 120 microfacies samples were inferred from these 14 wells. Besides, the average value of gamma, neutron and density logs as well as the sum of squares of deviations of gamma were extracted as key parameters to build log facies (facies from log measurements)?microfacies transforming model. The total 120 log facies samples were divided into 12 kinds of log facies and 6 kinds of microfacies, e.g. lagoon bioclasts micrite limestone microfacies, shoal bioclasts grainstone microfacies, backshoal bioclasts packstone microfacies, foreshoal bioclasts micrite limestone microfacies, shallow continental micrite limestone microfacies and reef limestone microfacies. Furthermore, 68 samples of these 120 log facies samples were chosen as training samples and another 52 samples were gotten as testing samples to test the predicting ability of the discrimination template. Compared with conventional methods, like Bayes stepwise discrimination, both the BP-ANN and PSO-BP-ANN can integrate more log details with a correct rate higher than 85%. Furthermore, PSO-BP-ANN has more simple structure, smaller amount of weight and threshold and less iteration time.