Well Logging Evaluation Of Volcanic Reservoirs With "the Multi Minerals Model"

With the development of oil and gas exploration,people gradually start to pay attention to the subtle reservoir.Reservoir igneous lithology characters has become the focus of exploration targets of complex lithologic reservoir.After 40 years of exploration and development, the deep gas reservoir in northern songliao basin has obtained commercial gas flow output at about one million square (open flow potential).It approved the prospect of exploration and development will be very good.So far,we generraly use the logging data and experimental data to build a model.Then write a program to calculate the reservoir parameters and evaluate the content of oil and gas.This method did not completely use the logging data and experimental data. In different storage we can not use the interpretation model and evaluation method flexible. To contain two kinds minerals or more complex reservoir minerals, we could not properly evaluate.It seriously affects the study of complex reservoir evaluation method.The igneous rock formation in Xujia Weizi is very complex and lithology is so complicated, and although the lithology is the same the parameters of skeleton parameters are offen change,so it may appear error when calculate the components for this strata.The common logging interpretation method can not used in igneous rock reservoirs.In order to speed up the development of oil and gas exploration and establish a system specification that is based on the reliable theory, we need to research a new method.Firstly we summarize the charateristics of the logging response in songliao basin,it provide the basis for lithology identification. Secondly GR-PE and GR-TH crossplot were be used to identify the lithology in this area.The effect is good,the coincidence rate reached more than 80%. These two chart can clearly divided the igneous rocks into basic lithology, neutral lithology, neutral to acid lithology, acidic lithology. Thirdly in this paper we make full use of the element content by Elenmental Capture Spectroscopy Sonde(ECS), skeleton density, neutron porosity, capture cross section, Photoelectric Absorption Cross-section Index. According to CEPW standard points I make the mineral elements content of conversion to standard mineral content by different lithlogies.The calculation of skeleton density compared with the density of core sample,the precision is 78%.In this paper we use the multi minerals model and rock frame parameters by schlumberger to get each mineral parameters in logging.Finally, according to the actual situation in song liao basin,the multi mineralsmodel has been established based on the QAPF classification method:Quartz, Alkaline feldspar, Plagioclase, Dark minerals and porosity. And using the mineral parameters, density and acoustic time, neutron porosity, natural gamma, Photoelectric Absorption Cross-section, a computational method has been established by over-determinated epuations that can solve out each mineral content in stratum.In this paper two wells in Xujia Weizi have been dealed.The porosity that calculated compared with core analysis,the anastomosis of the result is well and the average absolute error is 0.15%,the relative error is 1.73%.