Study Of Underground Capillary Pressure Curves Measurements And Their Influence On Development Performance

Capillary pressure curve is basic data for development program formulation andcalculation. Nowadays, capillary pressure curve measurement in laboratory is to measure therelationship of pressure and non-wetting phase saturation, then convert the curve intocapillary pressure curve under formation condition with the wetting angle and fluid interfacialtension force. However, the wetting angle and interfacial tension force of the fluid rocksystem can not be measured precisely, so the conversion calculated capillary pressure curvesunder reservoir condition have a certain error. Thus, the calculated oil water distribution intransition zone is not accurate.Aiming at the situation of inaccurately measurement of underground capillary pressurecurves, diaphragm method is used in this dissertation to emulate the real oil water fluidsystem and underground pressure conditions, and to measure the real underground capillarypressure curves, including oil water drainage capillary pressure curves, water oil imbibitioncapillary pressure curves, water oil imbibition capillary pressure curves with the initial watersaturation less than connate water saturation, and CO2oil drainage capillary pressure curves.Also, mercury injection capillary pressure curves of the same cores are measured andconverted to compare with the oil water capillary pressure curves. Capillary pressure curvesaffecting factors are discussed, and capillary pressure curves’ effects on different models’development performance are also studied with numerical simulation.The study shows that, the measured oil water capillary pressure curves can be usedinstantly without conversion. Mercury injection capillary pressure curves and oil watercapillary pressure curves can be transformed with a certain coefficient, but the transformcurves can not be matched completely. Core pole structure, measuring methods and rockwettability all have influence on the shape of capillary pressure curves. Different capillarypressure curves has different impacts on the oil water transition zone, initial oil water distribution and oil water producing performance during development of the simulationmodels.