Well Logging Reservoir Evaluation Of Shahejie Formation In Dagang Shallow Sea Area

With the unmatched relationship between energy supply and demand and the gradual deepening of reservoir development,complex reservoirs,especially thin bed and low-permeability ones,have been playing a more and more important role in the new reserves and petroleum production.In the shallow sea fields of circum-Bohai Bay area which is the hotspot,thin bed and low-permeability reservoirs develop widely.Thin-bed, low-permeability and low-resistivity are the three main characters of these reservoirs.Limited by the resolution of logging instrumentation and interpretation methods,there are many problems in the thin-bed recognization,fluid interpretation and reservoir paramater interpretation.All the problems above limite the accuracy and credibility of reservoir evaluation and become barrier of reservoir development.Taking the well logging evaluation research of Shahejie Formation in Dagang oil field, Bohai Bay as an example, the log-curve high resolution process,which aims to thin-bed reservoir,and the fluid interpretation methods are carried on, and then, a suit of methods for reservoir evaluation with well logging is built. In this research, three innovative results are obtained as follows:1) processing log-curves with the method of blind deconvolution, which can decrease the influce of surrounding rock on the thin beds in logging and can improve the log-curve's resolution;2) obtaining new logging parameters for thin bed evaluation with Hilbert transform;3) building a suit of fluid identification methods for the low permeability reservoir of our research area.Make reservoir evaluation research with the above methods in the research area, 1)make interpretation and evaluation of reservoir parameters based on the research of the relationship of lithology, petrophysical property and fluid-bearing property;2) establish criterion for reservoir classification: oil sand AC≥225μs/m,RT≥4.5??m, dry sand AC≥210μs/m, water sand AC≥245μs/m, RT<4.5??m; 3) characterize the heterogeneity of interlayers and inside layers; 4) make research on the origin factors of the low-permeability and low-resistivity properties and then establish a suit of methods to recognize the fluid of the reservoir based on the analysis of the origin factors above; 5)make reservoir classification with multi-parameters, such as lithology, petrophysics, thickness and well test. 6) classify the reservoirs into three hierarchies by parameter optimise and BP network.In this dissertation, a suit of well log interpretation and reservoir evaluation methods for our interesting area is developed,this is meaningful for reservoir evaluation research based on well logging in shallow sea field of Dagang and other similar areas.