Combined use of Confocal Laser Scanning Microscopyand PVT simulation for estimating the composition andphysical properties of petroleum in fluid inclusions
- 作者：Aplin ; A.c. ; Macleod ; G. ; Larter ; S.R. ; Pedersen ; K.S. ; Sorensen ; H. ; Booth ; T.
- 关键词：Confocal microscopy ; PVT simulation ; fluid inclusions ; palaeobarometry
- 刊名：Marine and Petroleum Geology
- 出版年：1999
- 期刊代码：37_02648172
- 类别：pw
- 出版时间：March 15, 1999
- 卷：16
- 期：2
- 页码：97-110
- 文件大小：367 K
摘要
We present a method to determine the composition and PVT properties of petroleum inindividual petroleum fluid inclusions. Confocal Laser Scanning Microscopy is used to generatethree dimensional images of single petroleum inclusions. Because liquid petroleum fluorescesunder the laser, the images readily distinguish the liquid and vapour within the inclusion and canbe used to determine the inclusions volumetric liquid:vapour ratio. Using PVT modellingsoftware, the liquid:vapour ratio is used along with the homogenisation temperature to determinethe bulk composition, phase envelope, isochore and a range of physical properties of the includedpetroleum. This is done using an iterative series of PVT calculations which match twoparameters: (1) the molar volume of the petroleum at room and homogenisation temperatures; (2) the liquid:vapour ratio of the inclusion at room temperature. Key uncertainties in the methodare explored, including the accuracy with which the liquid:vapour ratio can be determined; thecomposition of the titrant gas used in the iterative procedure; and the composition of thepetroleum chosen to model the physical properties of the included petroleum. Data from coevalinclusions suggest that the saturation pressure, Gas–Oil Ratio, viscosity, molar volume, densityand surface tension of included petroleum are determined with a precision of a few percent.Confirmation of the accuracy of the method awaits tests using inclusions grown in the laboratoryunder carefully controlled PVTX conditions. However, it is likely that the physical properties ofincluded petroleums are more accurately modelled by fluids which are genetically related tothem. If proven to be accurate, the method will provide a routine method for determiningpalaeopressure in petroleum systems. Finally, we present data from a Central North Sea examplewhich are geologically realistic and which for the first time record the evolution of fluid pressureand petroleum composition in a petroleum reservoir.