镇原-泾川地区储层下限标准的研究

RESEARCH OF THE LOWER LIMIT OF RESERVOIRS IN CHANG 6-8 OIL RESERVOIR SETS, ZHENGYUAN- JING CHUAN AREA

镇原-泾川地区延长组长6-长8储层属于低孔-特低渗透型储层,储层下限标准的研究是划分有效储层的基础,也是油层识别和容积法储量计算的前提.通常认为,低于下限标准的储层是不具备产能的.依据毛管压力资料,通过帕塞尔法、渗透率敏感法、相对渗透率曲线与毛管压力曲线叠合法、孔喉分布4种方法对该区储层下限进行研究. 结果表明,有效储层的孔喉下限约为0.25μm,与孔喉下限对应的渗透率为0.1×10-3μm2,孔隙度为8%.然而储层下限受地质因素和现有储层改造技术的影响,其值也不是一成不变的.因此,必须结合油藏的实际情况,对储层下限做出适当的调整.

Chang 6-8 oil reservoir sets have relatively lower porosity and much lower permeability in reservoirs in Zhengyuan and Jingchuan area. Research of lower limit of reservoir set is not only the base for disdinguishing effective reservoirs from non-effective ones, but also the precondition of identifying oil reservoir and reserve calculation with volumetric method. General speaking , it's hard for reservoir which is below the lower limit of reservoir to produce oil. We have researched the lower limit of reservoir by the method of Purcell, the sensitivity of permeability, the superposition of relative permeability and capillary pressure curves, distribution of throats at the base of information of capillary pressure. Our research indicates that the lower limit of throats is 0.25μm, the low limit of permeability and porosity which are corresponding with the lower limit of throats is 0.1×10-3UUUUm2 and 8% respectively. However, the lower limit of reservoir may change because of geological complications and the reconstructive measures upon reservoir. We should adjust the lower limit of reservoirs according to the actual conditions of reservoirs.