The Study Of Seismic Response Characteristics Of Dolomite Reservoirs

Carbonate reservoir is an important oil and gas reservoir,which is a hot and difficult point in geophysical exploration.Carbonate reservoir rocks are characterized by strong heterogeneity and anisotropy,as well as complex pore structure and diverse pore types.These characteristics make existing laboratory testing methods bring great challenges to the study of carbonate reservoir elastic characteristics.Therefore,it is of great significance for carbonate reservoir exploration to collect carbonate rocks from different areas for experimental study.In this paper,the appearance and microscopic characteristics of 61 samples collected from three regions were firstly analyzed,and the carbonate rocks were divided into dolomite and limestone,and then the samples were classified into 6categories according to particle size,mineral composition and pore structure.It is found that the pore permeability relationship and pore structure are different in the three regions.The pore permeability relationship of the samples in northwest China is exponential,while that in southwest China is not obvious.Secondly,some factors affecting the errors and accuracy of laboratory small diameter plunger samples under normal temperature and pressure were analyzed experimentally.In order to avoid the leakage phenomenon caused by torsion transducer,shear transducer was selected to measure the shear wave during the experiment.Under the pressure condition,it is found that the pressure time has no influence on the accuracy of velocity measurement,but has some influence on the amplitude study.Finally collected 61 pieces of samples under the dry and water saturation is the atmospheric pressure and pressure under the condition of the speed of testing,found in northwest in tahe area,limestone of p-wave velocity mineral composition,is the main controlling factors in limestone containing argillaceous biggest influence for the vertical and horizontal wave velocity of the sample,main controlling factors of the dolomite of p-wave velocity particle size,the smaller the particle,the greater the speed.The main controlling factor of the velocity of carbonate rock in Pengzhou area is mineral composition.The main controlling factors for the velocity of vertical and horizontal waves of carbonate rocks in Yuanba area are mineral composition and pore structure.In micrite bioclastic limestone,the higher the bioclastic content is,the lower the velocity will be,and the greater the velocity change will be under pressure.In carbonate rocks with fractures,the velocity change will be obvious under pressure.