Discussion on problems in temperature measurement of fluid inclusions in sedimentary rock

摘要

The analysis of fluid inclusions in sedimentary rock is one of the important ways to study the migration and accumulation of oil and gas, in which a microscope and a heating and freezing stage are used for measuring the homogeneous temperature and ice-point temperature and through the correction of them, the temperature and pressure of oil-gas accumulation are obtained for the research on migration direction and accumulation stages of the oil and gas. However, there are many factors in the measurement which can influence the reliability of the results, and some practical problems in the process and their preliminary means of settlement will be discussed in this paper. The samples from Shengli oilfield are mostly cemented by carbonate rock and as a result, the of quartz overgrowth is not widespread and the inclusions are mainly developed in the fracture of quartz grains. It is relatively difficult to determine the formative stages of inclusions in fracture, because there may be a wide range of homogeneous temperature among them and it is often to obtain obviously different data in the same fracture. For example, in the measurement of samples from Well Che660, the difference of homogenous temperatures of fluid inclusions in a same fracture of quartz grain is as high as 20°C～50°C. The reasons for this are that the fluid inclusions may: 1) be captured in different periods, 2) be captured with non-homogeneity, and 3) grew together a second time after distortion. The homogenous temperature is meaningful in the first circumstance, but can create misunderstanding in others. In the process of measurement, we Shave distinguished the factors resulting in temperature differences through various methods to remove the invalid data and ensure the accuracy and credibility of it, and the main methods are given below.