特低渗透储层微缝特征及对注水开发效果的影响

通过对大庆头台地区扶余油层描述研究入手,特别指出了除显裂缝之外的微裂缝系统,它对提高储层岩石的渗流能力,提高特低渗透油藏的开发效果有着十分重要意义。本文首先描述特低渗透储层的岩块及显裂缝系统及其特征,指出显裂缝系统大致由四组裂缝组成,长度大于2cm,渗流能力很强,约为岩块系统的1100倍;岩块系统包括基质和微缝部分,微缝一般长度小于2cm,规模小,包括岩块之内。微缝和岩块基质的储渗条件差别很大,微裂缝的渗流能力是基质渗流能力的83倍。其次描述了特低渗透储层微裂缝发育特征,指出微缝呈条带性分布,并且微缝间呈平行或雁式排列,具有明显的方向性,条带性随着岩性的变化而变化。微缝又可划分为有效缝和无效缝,有效缝对渗流起作用,无效缝充填方解石,对渗流不起作用。第三论述了特低渗透储层微裂缝对注水开发效果的影响,指出在线状注水排距210m条件下,徽缝发育区适合于线状注水,注水后压力比较低,油井产量相对较高。总之,本研究对特低渗透储层评价研究及经济有效投入开发具有重要指导意义,开拓了一个新的领域。

THE EFFECTS OF MICROFRACTURES FOR DEVELOPMENT THE LOWEST PERMEABILITY RESERVIOR IN WATER INJECTION

This paper described lowest fracture reservoir structure, especially the micro fractures in rock mass starting from study ofcharacteristics of reservoir, it has very important significance for enhancing the result of developing the lowest permeabilityreservoir. There are four microfracture groups in the micro fracture system, with a length of more than 2 cm and percolation a-bility of 1100 times as large as rock mass system. A rock mass system is consisting of matrix and microfracture. The length ofmicro fracture is less than 2 cm. It has the small scale in the rock mass. There is a big difference in the percolation ability be-tween the microfracture and the matrix with that of former is 83 times as large as the latter. In terms of the microfractures char-acteristics of the lowest reservoir, it distributed like zone and is in parallel or "wild goose" array with constant direction. Mi-crofracture zones vary as the property of rocks. The microfractures are divided into effective and ineffective ones. The effectivemicro fracture may play an important role in liquid percolation while the ineffective microfracture may not because of filling calcitein them. The paper also described the effects for the development of the lowest permeability reservoir at injecting water mode.The reservoirs with more microfractures would be suitable to linear injection under 210 m of row distance. With the small inject-ing pressure, a high oil production would be maintained. In conclusion, this study has very important meaning for the evaluationand economic development of lowest permeability reservoir, and creates a new study area.