Experimental Study on Fluid Occurrence Characteristics of Class II and III Conglomerate Reservoirs in Mahu Baikouquan Formation

Abstract By using geochemical characterization methods such as multi temperature pyrolysis experiments and solvent stepwise extraction experiments, combined with nuclear magnetic resonance T1/T2 spectra, the crude oil occurrence characteristics and distribution patterns of tight conglomerate II and III reservoirs in the Mahu Baikouquan Formation were clarified, forming a set of two-dimensional nuclear magnetic fluid occurrence maps of the Mahu Baikouquan Formation. Combining centrifugal experiments to compensate for the loss of light hydrocarbons during core drilling, transportation, and storage, based on rock multi temperature pyrolysis experiments and solvent stepwise extraction experiments, it was determined that the free oil content of Class II reservoirs was 78% and the adsorbed oil content was 22%, while the free oil content of Class III reservoirs was 65.5% and the adsorbed oil content was 34.5%. The free oil saturation of Class II reservoirs was higher than that of Class III reservoirs; The two-dimensional nuclear magnetic resonance spectra of saturated pure water and simulated oil in saturated formations characterize the occurrence characteristics and distribution states of fluids in Class II and III reservoirs, clarifying the identification of longitudinal/transverse relaxation times for bound water, free water, adsorbed oil, and free oil. The content of free water and free oil is proportional to permeability; The two-dimensional nuclear magnetic resonance spectrum experiment of rock cores containing bound water shows that adsorbed oil mainly exists in pores<0.5 μ m, free oil mainly exists in pores>0.5 μ m, bound water mainly exists in pores<0.1 μ m, and free water mainly exists in pores>0.1 μ m, providing basic data support for the formulation of later development strategies.