【作者】 任晓娟；

【导师】 曲志浩；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2006， 博士

【摘要】 流体在低渗透储层中的渗流规律明显不同于中高渗储层,因此研究和认识低渗储层岩石孔隙结构及其流体的微观渗流规律对认识低渗层流体的渗流规律具有重要的意义。本文对10个油气区块低渗砂岩储层岩石的孔隙结构进行了全面系统的研究和分析对比,在此基础上对低渗储层岩石的表面性质及储层岩石表面弱亲油性质存在的原因进行了分析研究;同时砂岩微观模型实验和岩心实验在微观尺度上和岩心尺度上对弱亲油低渗储层岩石中油水的渗流规律及其影响低渗储层油水渗流的主要因素进行了大量的室内实验研究,主要取到以下认识: （1） 成岩作用的强弱、填隙物成分、岩石颗粒之间的接触关系、孔隙类型是影响低渗储层岩石孔隙结构的重要因素。低渗砂岩储层岩石渗透率与孔隙度存在正相关关系,毛管压力曲线形状复杂,孔喉分布多呈双峰、多峰分布,孔隙结构参数之间及随孔隙度、渗透率的变化存在一定的规律。根据本文提出的结构渗流系数的概念,从孔隙结构的角度将储层分成了四类,Ⅰ类孔隙结构储层为一般低渗储层,渗透率大于1.6×10^-3μm²;Ⅱ类孔隙结构储层为特低渗储层,渗透率范围在1.6～0.8×10^-3μm²;Ⅲ类孔隙结构储层为超低渗储层,渗透率范围在0.8～0.3×10^-3μm²;Ⅳ类孔隙结构储层为致密层,渗透率小于0.3×10^-3μm²; （2） 低渗储层岩石表面粗糙、结构复杂、表面积大、电性强,一般具亲水性,低渗储层岩石表面的亲油性是由于表面存在弱亲水性的矿物及原油中极性物质的存在造成; （3） 低渗弱亲油储层的油水分布及油水微观渗流特征明显不同于亲水储层,存在孔隙表面自发的界面流动现象,润湿性对驱油效率影响不明显,孔隙结构是影响低渗储层水驱油效率的主要因素; （4） 润湿性对低渗储层油水相对渗透率曲线特征具重要影响,但其影响规律明显不同于中高渗储层,渗透率和储层的微裂缝对低渗储层油水相渗曲线的形状影响显著,但不同润湿性条件下其影响规律明显不同。 本文取得的研究成果对划分评价低渗储层及认识低渗储层油水渗流机理具有较大的理论意义。更多还原

【Abstract】 It is very significant to research the pore structure and fluid flowing in low permeability porous media because the flowing in low permeability reservoirs is different from high-middle permeability reservoirs. The pore structures of ten oil and gas rock layers in different oil fields have been studied completely. This paper has also researched the surface characteristics of low permeability rock, the reason of oil-wet property in low permeability rocks, the oil and water flowing in weak oil-wet low permeability porous media and the factors affecting on oil and water flowing by use of sand micro-models and core experiments. The results are as follows:1. The degree of diagenesis, the composition packed in pore, the contact association between particles and pore type are the important factors affecting on the pore structure of low permeability rocks, and the permeability of low permeability rocks has the relation to the porosity positively.2. Mercury capillary cures have complicated shapes. Thus the pore distribution is commonly double or multi-peaks distribution. The pore structure parameters are some related to rock permeability and porosity, and some parameters have connection with one another. The structure flowing coefficient is brought forward for expressing affecting ability of pore structure on fluid flowing. Based on the structure flowing coefficient, low permeability rocks are divided into four kinds, that is, Ⅰ type of pore structure rocks, its permeability is more than 1.6×10^-3μm², is general low permeability reservoir;Ⅱ type of pore structure rocks, its permeability is 1.6-0.8×10^-3μm², is lower permeability reservoir;Ⅲ type of pore structure rocks, its permeability is 0.8-0.3×10^-3μm², is super-low permeability reservoirs;Ⅳ type of pore structure rocks, its permeability is less than 0.3 ×10^-3μm², is dense low permeability reservoirs.3. The rock of low permeability reservoirs has rough and complicated surfaces, and its surface area is larger and more electric, and of hydrophilic property. The weak water-wet minerals and the polar substances absorbed on rock surface will make the surface of low permeability rock oil wet.4. The oil and water distribution and flowing in weak oil-wet low permeability rock are different water-wet rock, and oil phase can flow on rock surface spontaneously. It is not the main factor affecting on displacing oil efficiency, and the pore structure is the main factor of influence on displacing oil efficiency.5. There is the important influence of wettability on oil and water relative permeability curve of low permeability cores, and it is very different from high-middle permeability cores. The permeability and micro-fracture are the primary factors affecting on the curve shape of the relative permeability of low permeability cores, and their influence is very various because of the different wettbility.These results are very important to valuate low permeability reservoirs and realize the oil and water flowing mechanism through low permeability pore media on theory.更多还原