Experimental Study On Factors Affecting The Velocity Of Cambrian Carbonate Reservoirs

In recent years,the focus of China's oil and gas exploration has gradually shifted from conventional reservoirs to deep and ultra-deep reservoirs.Fewer exploratory wells have encountered such reserviors,so the data in the wells are scarce and lack basic rock physics data.Thus,this paper takes the Cambrian carbonate outcrop samples from the Tarim Basin in the Aksu area as the research object,and conducts basic lithological observations on the outcrop samples on the four geological sections.The velocity and porosity of the samples are measured under indoor and pressure conditions respectively.The permeability parameters were tested.The experimental results show that most samples of Cambrian carbonate samples in the Aksu area of Xinjiang have different macroscopic minerals and mineral gravel.The longitudinal and transverse wave velocity ranges under temperature and pressure are 4680m/s-6814m/s and 2722m/s-3495m/s with large heterogeneity;Under the pressure condition,the longitudinal wave velocity shows a significant step-like change,and the transverse wave velocity rises relatively gently.According to the heterogeneity of the sample,we proposed a method for observing the heterogeneous characteristics of the sample by using the polarization characteristics of the shear wave.By testing the polarization direction of the transverse wave,it is known that the heterogeneous characteristics of carbonate samples can be divided into three categories:velocity heterogeneity,amplitude heterogeneity,and velocity amplitude are heterogeneous.This heterogeneity is mainly caused by the distribution and size of the minerals in the sample,and may also have the effect of cracks.