Study On Log Evaluation Method For Pyroclastic Rocks

Porosity and permeability of reservoir are the basic and important parameters in the interpretation of well logs. They are very important basis for computation of the reserve of oil-bearing reservoirs. For such complex pyroclastic rock formation, a single old log is not sufficient to calculate the formation parameters. Basing on the prior investigations on the method of calculating reservoir parameters, this paper searches method suitable for calculating formation parameters in pyroclastic reservoirs.This paper investigates the volcanic clastic reservoirs in the Hailar Basin Wuerxun - Bell Depression. As the pyroclastic rock reservoirs have complex lithology and logs logged by several kinds of logger. Logging data will be standardized so as to control the quality of logging data. This paper attempts to explain the use of traditional methods of interpretation of well logs in pyroclastic rock reservoir, but failed to achieve satisfactory results.These investigations are held in Hailaer basin of Daqing oil field. Firstly, there is the standardization of processing for logging date.Other floors will be corrected by the standardization of data. The corrections of the logs eliminate the influences of the many factors.After the standardization, the real situation of underground could be more accurately reflected by the logging data.Generally, logging data standardization on the basis of a region with a layer has the same geological characteristics of geophysical, so different well from the logging data of the same type have own distribution. When the standard layer of the key well have been established after the standard distribution pattern of oilfield, the influences of the many factors will be eliminated by the relevant technical analysis of the wells and a comprehensive analysis of data logging。The second is skeleton parameters of the martrix.It's an important part of strike porosity and saturation.This paper is through the frame components to calculate the parameters.At present, the oil and gas layer of explanation are restricted by the identification of reservoir and lithology in Hailar basin. The complication of ithology and diverse ithology lead to log response character- ristics of clutter and the deterioration of law, and also influenced the rate of interpretation in the water layer.Finally, there is saturation and penetration of calculation. In formation evaluation and analysis of oil and gas, regional explained the parameters of a reasonable choice is very important.Porosity reservoir rock is the most important one of the physical parameters; it is mainly used to evaluate a reservoir and the reservoir capacity of the relative size. In accordance with fluid movement in the bay to the situation of freedom of the pore fluid can be divided into the pores and porosity. Free fluid pores are those of mutual connectivity, and in general under the conditions of fluid pressure in that part of which flows pore. The total pore or absolute rock is the sum of all the pore space of the whole, independent of the pore size, shape and porosity channel cross-section, regardless of whether they are closed or not.Formation permeability is a complex parameter, and calculated by logging data. It is influenced by the porosity of rock, clay content, particle size, separation and other factors affecting quality. The high-impact and credibility of the parameters are porosity. As the reservoir permeability and porosity of the structure is very close, so clastic rock formation penetration may be to some extent reflect the formation pore geometry of the size of the value of the function.The paper gives the basic principles and implementation approaches of logging data normalization and mathematical statistics. Some interpretation models were eliminated by the logging data and core analysis data of this region. Some well logging data were processed and get some basic conclusions on how to select and apply these interpretation models. A relative mature methodology which suited for pyroclastic rock reservoir in this region was gained. The work established an important base on distinguishing oil and water layer for the future.On the basis of the comparisons above, it can be found that a more precise value of saturation may be obtained.