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The volume ratio between vapor and liquid of hydrocarbon inclusions is an important parameter for PVT simulation. Moreover, the judgment of the boundary between vapor and liquid is very important for the accuracy of the vapor/liquid ratios. A method for accurately determining the volume of hydrocarbon inclusion has been developed in this study. High resolution Laser Confocal Scanning Microscopy was used to obtain three-dimensional images of hydrocarbon inclusions. The liquid phase boundary was determined by three-direction coordinates under transmission light and fluorescence. 3DforLSM software was used to calculate the liquid phase volumes of hydrocarbon inclusions. Line scan was carried out across the vapor and liquid boundary using Laser Confocal Fluorescence Microscopy, in order to determine the vapor phase boundary according to the change of fluorescence intensity. The average of the results from multiple scans was used as the diameter of the vapor phase. This method avoids the error of manual judgment of the vapor and liquid boundary with a precision of 0.02 μm. The method improved the analytical precision of vapor/liquid ratios and allows for more reliable reconstruction of the trapping pressure by hydrocarbon inclusions.

PVT simulation of hydrocarbon inclusions can be used to reconstruct trapping temperature and pressure. Vapour/liquid ratio is an important parameter affecting PVT simulation. However, due to the lack of a hydrocarbon inclusion standard, the accuracy of the vapour/liquid ratio measured by Confocal Laser Scanning Microscope (CLSM) has not been investigated. In this paper it is proposed that a synthetic hydrocarbon inclusion standard can be used for correcting CLSM and the theoretical vapour/liquid ratio of hydrocarbon inclusions can be calculated based on the known hydrocarbon composition, trapping temperature and pressure. The actual vapour/liquid ratio can be obtained by CLSM. The differences between the actual values and theoretical values can be used to calculate the error of actual vapour/liquid ratio, so as to complete the error calibration of CLSM. Experimental results confirm that the absolute error of CLSM with high resolution is less than 0.5%, and thus CLSM can provide accurate parameters for the PVT simulation of inclusions. This study affirms the accuracy of CLSM for determining the vapour/liquid ratio of hydrocarbon inclusions, and further confirms that PVT simulation of hydrocarbon inclusions can provide reliable data for hydrocarbon accumulation.

Shale evaluation is an important part of oil-gas geochemistry research and the basis for understanding potential of oil-gas resources. Taking the shale in the first member of Qingshankou Formation in JYY1 well in Changling Sag as object, the paper evaluates the heterogeneity on the basis of organic characteristics and well logging curves. It is considered that the shale mainly belongs to Types I and II of kerogens, in low mature-mature stage. The characterization model of reservoir heterogeneity and grading evaluation of shale show that the dark shale in the first member of Qingshankou Formation is mainly Level-II resource, partly Level-I and a little Level-III, and the overall resource level of source rocks in the upper member is better than that in the lower member of Qingshankou Formation. [ABSTRACT FROM AUTHOR]

There is a set of high quality semi-deep to deep lacustrine dark shale developed in the first member of Qingshankou Formation(K2qn¹) in Changling Sag, southern Songliao Basin, with large sedimentary thickness and stable distribution. A lot of residual hydrocarbon exists in shale layers with shale oil resource potential. Based on massive data of well logging, oil testing, core sampling and experimental test, the paper comprehensively analyzes the main controlling factors of enrichment including content and distribution of residual hydrocarbon, lithofacies assemblages, reservoir space and mineral compositions in the shale. The results show the residual hydrocarbon is mainly medium-light oil, with good fluidity and enrichment range of 1800-2500 m vertically. The shale of K2qn¹ can be divided into bedded, laminated and interbedded lithofacies types, and the content of residual hydrocarbon in the former two types is high, with TOC more than 1.5% generally, Type I and Type II1 of organic matters, pyrolysis Si more than 2x10-3, porosity more than 5.5%, mesoporous-macroporous pore size, brittle mineral content more than 50% and good fracturing property, which is the major enrichment pattern of shale oil. Through superposition of main controlling factors of enrichment and evaluation of favorable lithofacies, JYY-1HF well is optimized and deployed in Qian'an enrichment area and 16.4 m³/d of shale oil flow is yielded after fracturing. The shale oil resource of K2qn¹ in Changling Sag is estimated to be 35x108 t by pyrolysis S1 method, proving that the southern Songliao Basin has considerable shale oil resource potential. [ABSTRACT FROM AUTHOR]