Study Of Logging Interpretation For Tuffaceous Sands Reservoir In Wuerxun Depression

Currently, As the scale and depth continues to increase on oil and gas exploration, in many parts of the world, An increasing number of hydrocarbon reservoirs are found in pyroclastic rocks, for example, there develop a large-scale reservoirs of pyroclastic rocks in Hailar Basin of China. Volcaniclastic rocks are transition type rocks between magmatic rocks and sedimentary rocks, however,With the Pyroclastic rocks raservoir was found to have more and more, people are paying more and more attention to volcaniclastic reservoir evaluation. the current oil and gas exploration and production areas mainly concentrated in the Wuerxun - Bell depression in Hailar Basin, The main difficulty at present are low accuracy of exploration and the difficulty in discovery of oil and gas layer, which will restrict the pace of development of oil fields. Due to the broad distribution of tuffaceous, tuffaceous sandstone reservoir as the most typical and the most important reservoir, so the establishment of a tuffaceous sandstone evaluation method of logging will have a very important significance in Wuerxun-Bell depression of Hailar Bsain.. In the course of the study, first of all, basic data have been collected, collated and analyzed, then Reservoir geological characteristics and the lithology, physical property and the logging response characteristics of the tuffaceous sands reservoir have been studied. We find tuffaceous sandstones have complex composition, which skeleton contains clay and tuffaceous. Due to porosity, permeability, saturation by the impact of tuffaceous, so we need to determine the content of shale and tuffaceous. First,by determing the framework parameters, we establish total porosity regression formula, the computed porosity is very close to the porosity by core analysis.next, The authors research and analyze the ordinary logging methods which are used to calculate shale content. Aiming directly at the lithology this region and according to core analysis of clay content, This paper strikes the regression equations of shale content by multiple regression of the neutron density intersection method, natural gamma index empirical formula and resistivity empirical formula. in order to calculate the tuffaceous content,The volume model has been established, and tuffaceous sandstone skeleton are formed by sandstone (quartz, feldspar and lithic components), tuffaceous and muddy components, then by determing the framework parameters of the components, programming is used to strike all parts of the volume content. Quantitative interpretation of logging in the establishment of tuffaceous sandstone porosity equation effectively, we consider the impact of clay and tuffaceous on the porosity of logging, and then try to remove in order to seek effective porosity.Evaluation of oil and gas saturation is the core of quantitative evaluation of the oil layer, although a number of other well logging technology can also provide relevant information of the reservoir saturation, at present, the most use of log interpretation is still the resistivity-based saturation evaluation .This paper analyzes the saturation model at home and abroad, including saturation model consideration of the impact of clay, the skeleton and multi-porosity. in which Oshinobu Itoh Based on experimental data and found that the skeleton tuffaceous sandstone also have some additional conductive similar to clay.Therefore, this type of reservoir, the conductivity can not be fully in accordance with the Archie formula. Reference the Oshinobu Itoh saturation model, We has a certain improvement for the saturation model in view of tuffaceous sandstone. In the conductivity model, the additional conductive of clay can not be ignored, at the same time the existence of tuffaceous rocks increase the conductivity, This role is first called tuffaceous additional conductivity. Therefore, the resistance of tuffaceous sandstone will be parallel by the resistance of tuffaceous, muddy and the formation water. The water saturation computed in accordance with the established model contrast with the test conclusion accuracy rate reached 82%, greatly improving the accuracy of the saturation model application than the past in this region.By determing the formation effective porosity and hydrocarbon saturation, the layer can not be distinguished between the merits of the production layer, productivity and water content and so on, to solve such problems, it is necessary to know the permeability and irreducible water saturation and other parameters. Conventional logging data is not directly related with the penetration rate, the theory and practice show that: permeability and porosity and irreducible water saturation there is a good correlation. Under normal circumstances, penetration increase with the porosity rate increases, penetration reduce with the irreducible water saturation increases. In reservoir evaluation irreducible water saturation is a significant parameter, it is very important to determine the nature of fluid, estimate the oil and gas reserves and determine penetration rate. Although many methods of logging can reflect the water content of strata, there is no logging methods which can directly reflect the number of bound water. In this paper, statistical methods are taken, though multiple regression we establish regression equation which fit for determing the irreducible water saturation of the tuffaceous sandstone in Wuerxun depression. By calculating effective porosity and irreducible water saturation, we use the formula which contains irreducible water saturation and porosity in order to derive penetration rate. The porosity, saturation, permeability and irreducible water saturation computed in this article are applied to the specific paragraph of the wells, and have achieved good results.Using the information of core analysis and a variety of other methods to carry out the calculation of reservoir parameters, in this paper, There is a suit of logging interpretation system which fit for the tuffaceous sandstone in Wuerxun depression, they will be of great significance for the development of Reservoir Evaluation of tuffaceous sandstone.