Distribution Characteristics of Pore Fluid in Gulong Shale Oil by Nmr T1-T2 Spectrum

Abstract In view of the development of nano-micron pores and foliation fractures in the Gulong Shale and the complex law of fluid occurrence, the fluid distribution in five states of dry sample, saturated oil, saturated water, centrifugation and after gas drive is compared and studied through one-dimensional nuclear magnetic resonance and T1-T2 two-dimensional nuclear magnetic resonance experimental analysis. At the same time, the production characteristics of the Gulong Shale oil after gas drive are analyzed in terms of small, medium and large pores. The results show that the NMR porosity is larger than that of the weighing method due to the presence of fluid in the pores of shale samples before oil saturation; The organic pore oil phase and inorganic pore oil phase of the Gulong shale can be divided by T2=1ms. The two-dimensional spectrum signal of the fluid is mainly distributed in the range of T2=0.1-1000ms. The fluid types are mainly clay bound water, capillary bound water, inorganic pore movable water, organic pore light oil, asphaltene and inorganic pore oil phase. The distribution range of clay bound water, capillary bound water and inorganic pore movable water is T2=0.11ms, 1-10ms and 10-100ms respectively, The distribution range of organic pore light oil and asphaltene is T2=0.1-1ms, and the distribution range of inorganic pore oil phase is T2=1-1000ms; The asphaltene content in dry rock samples is 26.3%∼63.5%, the organic pore light oil content is 6.1%∼20.3%, the clay bound water content is 19.6%∼48.9%, and the inorganic pore oil content is 0%∼17.5%; The content of asphaltene in saturated oil samples is 4.2%∼32.9%, the content of organic pore light oil is 13.4%∼29.6%, the content of clay bound water and capillary bound water is 6.5%∼32.0%, and the content of inorganic pore oil phase is 36.0%∼47.5%. After the breakthrough of shale core gas drive, the recovery degree of shale oil has no obvious change. The oil phase in the large pore (or fracture) is the easiest to be used, while the medium pore oil phase is relatively difficult to be used, and the small pore oil phase is basically not used. The recovery degree of the medium pore oil phase is the key to affect the total recovery degree.