H区块长8致密油层水基压裂液伤害因素室内评价及分析

发布时间：2018-06-22 06:35

本文选题：致密油层 + 水基压裂液　；参考：《西安石油大学》2017年硕士论文

【摘要】：为使致密油气藏得以高效开发,常需采用大型压裂技术对储集层进行改造,因而不可避免的大量的压裂液会进入储层对储层造成不同程度的损害。本文以致密储层H区块为研究对象,首先分析和研究了该储层压裂液潜在的伤害因素,然后通过真实支撑剂微观模型、微裂缝微观模型以及岩心伤害室内试验、渗吸实验等,研究了压裂液对该区块致密储层基质、支撑裂缝以及人工微裂缝的损害机理及影响因素,得到以下主要认识及研究成果:(1)H区块储层属低渗致密储层,渗透率范围为0.0185~0.713mD,孔隙度分布在3.2%~13.9%之间,主要渗流空间为原生的残余粒间孔以及次生溶孔和次生溶蚀缝隙,同时微孔隙发育,为主要的储集空间;储层岩石孔喉半径细小,最大连通孔喉半径在0.5~2μm。潜在伤害因素主要有:水锁、水敏、对支撑裂缝的滤饼伤害、残渣伤害及对储层及压开微裂缝的固相伤害、乳化堵塞以及聚合物伤害。(2)研究区储层岩心对压裂液具有自吸水性,自吸水效率明显高于一般地层水,同时自吸后油返排存在明显的渗透率降低,但降低的幅度存在差异,因此本文认为可以用压裂液这种自吸水的差异性,来评价压裂液对基质的伤害程度,即先用建立好束缚水的岩心自吸压裂液,然后对比自吸前后岩心渗透率的差异,伤害率越低,而自吸效率越高的体系,为低伤害体系。本文称为致密储层压裂液自吸-驱替伤害评价方法,可以做为评价致密储层压裂液伤害的一个方法,并建议自吸时间设计成5000min较好。(3)压裂液残渣对支撑裂缝伤害严重,微观实验表明,陶粒支撑剂平均伤害率为37.06%,石英砂支撑剂平均伤害率为52.17%,压裂液残渣及滤饼对石英砂支撑裂缝伤害相对更严重,而陶粒返排残渣效果明显好于石英砂支撑剂。同时残渣及未破解的压裂液易形成较高的启动压力,而启动压力过高,会造成支撑剂的分散运移,因此对于大型压裂液残渣对裂缝的伤害是不容忽视的。(4)微裂缝微观模型实验表明,压裂液进入裂缝也存在启动压力,裂缝宽度越小,压裂液注入时启动压力越高;同注入压力下,裂缝渗透率随注入量增加不断减小,同压裂液体系下返排量增加3.5倍,伤害率降低幅度为38.3%。裂缝形态对微裂缝渗透率有一定的影响,裂缝形态弯曲度大、存在凹凸面的裂缝,压裂液残渣很容易堆积,不易返排,从而对微裂缝造成伤害。(5)用岩心人工微裂缝评价致密储层微裂缝的伤害率是一种可行的办法,但环压需稳定在7~10MPa范围。本文用该方法评价了三种未破胶压裂液体系,胍胶体系伤害最为严重。
[Abstract]:In order to develop tight reservoirs efficiently, it is often necessary to use large-scale fracturing technology to reconstruct the reservoir, so a large amount of fracturing fluid will inevitably enter the reservoir and cause damage to the reservoir to varying degrees. In this paper, the potential damage factors of fracturing fluid in tight reservoir H block are analyzed and studied firstly, and then through real proppant micro-model, micro-fracture micro-model, core damage laboratory test, permeation experiment, etc. The damage mechanism and influencing factors of fracturing fluid on tight reservoir matrix, supporting fracture and artificial microfracture in this block are studied. The main results are as follows: (1) the H block reservoir belongs to low permeability tight reservoir. The permeability range is 0.0185 ~ 0.713mD, the porosity is between 3.2% and 13.9%. The main percolation space is primary residual intergranular pore, secondary solution pore and secondary solution gap, and the micropore is the main reservoir space, and the pore throat radius of reservoir is small. The throat radius of Dalian is 0.5 渭 m. The potential damage factors are: water lock, water sensitivity, filter cake damage to support fracture, residue damage and solid phase damage to reservoir and microfracture, emulsification plugging and polymer damage. (2) Reservoir core in the study area has self-absorbency to fracturing fluid. The efficiency of self-suction is obviously higher than that of normal formation water, and the permeability of oil reflux after self-suction is obviously decreased, but the range of decrease is different, so this paper thinks that the difference of self-suction water can be used in fracturing fluid. In order to evaluate the damage degree of fracturing fluid to matrix, that is to say, the core self-priming fracturing fluid with good bound water is used first, and then the difference of core permeability before and after self-priming is compared. The lower the damage rate and the higher the self-priming efficiency, the lower the damage system. This paper is called the evaluation method of fracturing fluid self-priming and displacement damage in dense reservoir. It can be used as a method to evaluate the damage of fracturing fluid in dense reservoir. It is suggested that the self-priming time should be designed as 5000min better. (3) fracturing fluid residue has serious damage to supporting fracture. Microscopic experiments show that the average damage rate of ceramsite proppant is 37.06, and that of quartz sand proppant is 52.17. The fracture damage caused by fracturing fluid residue and filter cake is more serious than that of quartz sand support. At the same time, the residue and the uncracked fracturing fluid are easy to form higher starting pressure, and the high starting pressure will cause the dispersed migration of proppant. Therefore, the damage caused by the residue of large fracturing fluid to the fracture can not be ignored. (4) the micro-fracture model experiment shows that the fracture fluid entering into the fracture also has start-up pressure, the smaller the fracture width is, the higher the starting pressure is when the fracturing fluid is injected; Under the same injection pressure, the fracture permeability decreases with the increase of the injection rate, and the back flow rate increases 3.5 times and the damage rate decreases by 38.3 times under the same fracturing fluid system. The fracture form has certain influence on the permeability of micro-fracture. The fracture form has a large bending degree, there are concave and convex fractures, the residue of fracturing fluid is easy to pile up, and it is not easy to return to discharge. It is a feasible method to evaluate the damage rate of microfractures in tight reservoirs by using artificial microfractures in cores, but the ring pressure needs to be stabilized in the range of 710 MPA. In this paper, three kinds of unbroken fracturing fluid systems are evaluated by this method, guanidine gel system is the most serious.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE357.12

【相似文献】