Laboratory Evaluation And Analysis Of The Damage Factors Of Water Fracturing Fluid In Chang 8 Tight Reservoir Of H Block

In order to make the development of tight oil and gas reservoirs efficiently,it is often necessary to adopt large-scale fracturing technology to reconstruct the reservoir,so that a great deal of fracturing fluid will inevitably enter into the reservoir to cause different damage to the reservoir.The tight reservoir in H block as the research object,firstly analyzes the harm of the reservoir fracturing fluid potential factors and research,and then through the real proppant microscopic model,micro cracks and micro model of core damage test,imbibition experiment,study the fracturing fluid to the reservoir block matrix,support factors artificial cracks and micro cracks damage mechanism and effect,get the following main research results and understanding:(1)H reservoir belongs to low permeability reservoir permeability,porosity distribution in the range of 0.0185~0.713 mD,3.2%~13.9%,the main seepage space for primary residual intergranular pores and secondary pores and secondary dissolution pore gap,and development,in space as the main reservoir;reservoir rock pore throat radius is small.The largest connected pore throat radius in 0.5~2μm.Potential damage factors include water lock,water sensitivity,cake damage,residual damage,solid phase damage to the reservoir and micro cracks,emulsion plugging and polymer damage.(2)the study area of reservoir cores with self absorption of fracturing fluid,water efficiency was higher than that of formation water,and self-priming oil flowback obvious permeability decreased,but there are differences in lower,so it can use the fracturing fluid water difference to evaluate the degree of matrix the fracturing fluid,i.e.with the established bound water imbibition core fracturing fluid,then compare the differences before and after imbibition core permeability,damage rate is low,and the higher the efficiency of self suction system for low damage system.This paper is called the method of self Imbibition Damage Evaluation for tight reservoir fracturing fluid,which can be used as a method to evaluate fracturing fluid damage in tight reservoir.It is suggested that the design of self absorption time is better than 5000 min.(3)fracturing fluid residue serious to support micro crack damage,experiments show that the proppant average damage rate is 52.17%,quartz sand proppant average damage rate is 37.06%,fracturing fluid residue and filter cake of quartz sand to support fracture damage more serious,while ceramsite flowback residue is better than quartz sand proppant.At the same time and did not crack the residue of fracturing fluid is easy to form high starting pressure,the starting pressure is too high,will cause the dispersion of proppant,so for large scale fracturing fluid residue damage to crack can not be ignored.(4)the micro fracture micro model experiment indicates that the fracturing fluid into the cracks are starting pressure,crack width is small,the fracturing fluid injection starting pressure is high;the same injection pressure,permeability decreases with the injection quantity increased,with the fracturing fluid system under the backward displacement increase 3.5 times,the damage rate is reduced by 38.3%.Fracture morphology has a certain impact on the micro fracture permeability,fracture morphology is large,there are concave convex cracks,fracturing fluid residue is easy to accumulate,not easy to row,thus causing damage to the micro cracks.(5)it is a feasible way to evaluate the damage rate of micro cracks in tight reservoir with the core micro fracture,but the ring pressure should be stable in the range of 7~10MPa.In this paper,three kinds of fracturing fluid system are evaluated by using this method.