Evaluating of formation quality by interating core data and well log data in E sequence, X oilfield, Cuu Long Basin

Abstract

The X oilfield has a total of 4 wells, namely 1X, 2X, 3X and 4X. Sediment E sequence of X oilfield is the object of research in this study and has been determined to consist of 3 main distribution (E3, E4 and E5) and the distribution E clay above. Well logging measurements were performed throughout the E sequence for all 4 wells, core samples were taken at distribution E4 (at well 2X and 3X) and E5 (at well 4X). From the research results, it is shown that the formation of E sequence set has poor to moderate quality, but there are locations with good porosity and permeability. The low clay content in the reservoir (the average value of core samples for wells 2X, 3X and 4X is 6.96%, 8.94% and 5.7%, respectively, is a favorable factor for flow in the reservoir. The porosity-permeability relationship has a high correlation coefficient, so it is possible to trust this relationship to calculate the permeability for locations where the permeability measurement from the core sample is not performed. In order to evaluate the formation quality E of X oilfield accurately and comprehensively in all aspects, it is necessary not only to rely on core analysis and well-logging data, but also needs to be combined with conducting DST (Drill Stem Test), as well as other geological and stratigraphic methods.The results of the determination of porosity and permeability are not the same in 4 wells, showing the complicated change of facies of E sequence in the structure of X oilfield, so when simulation a wells, it is necessary to be careful and consider carefully based on building a map of the distribution of facies, in order to contribute to improving the efficiency of the oil and gas search and exploration process, reduce geological and economic risk factors, and provide more information to evaluate accurately and efficiently price oil and gas reserves.