| The oil and gas reserves of carbonate rock reservoirs account for60%of theworld’s total reserves. With continuous progress of the exploration and developmenttechnology, acid fracturing modification technology has become the main measure ofmining, production, stable production of this type of oil and gas reservoir, its basicgoal is the formation of wider range, higher flow conductivity of acid corrosionfracture in carbonate rock reservoirs. Therefore, the size and distribution of acidcorrosion fracture conductivity directly determines the acid fracturing effect. At thepresent, the two main methods of acid corrosion fracture interval conductivityresearch are empirical formulas and indoor experiment, which cannot truly andeffectively make quantitative analysis of the formation and evolution laws of acidcorrosion fracture interval conductivity of carbonate rock reservoirs. This led tocertain blindness of the carbonate rock reservoir acid fracturing technology design.The fracture surface morphology is the major controlling factor of conductivity.Conventional fracture conductivity research measures can neither make quantitativeanalysis of the corresponding relation between fracture surface morphology andfracture surface description, nor make any explanations of the closure law in terms ofmicro-morphology characteristics. This paper systematically summarized andanalyzed the previous research results on fracture micro-morphology features,analyzed the influence of fracture interval distribution of fracture closure law bynumerical accumulation method and area integral method, through combination offracture closure amount model and cubic law of slit, predicted acid corrosion fractureconductivity under different fracture interval distribution law. This paper obtained thefollowing result through research:(1) Summarized and analyzed the defects of the acid corrosion fractureconductivity research method focused on the fracture surface coincidence degree, in combination with fracture fluid flow characteristics, put forward such research an idea,to study the relationship between non-anatomized fracture surface and conductivity.(2) Through digital imaging analysis of splitting rock core surface, obtainedanalog fracture corrosion surface morphology image and the interval distribution ofclosed acid corrosion fracture.(3) In combination with the acid-rock reaction mechanism and the fracturesurface morphology law to clarify the physical meaning of the acid fracturingcorrosion fracture interval and its influence mechanism on conductivity.(4) With two methods of numerical accumulation method and area integralmethod to calculate the initial openings and conductivity of acid corrosion fractureunder atmospheric pressure.(5) In combination with the fracture closure amount model and the slit cubic law,predicted the acid corrosion fracture conductivity under different closure stressconditions, the effect is better.This paper aims to summarize and analyze the research methods of acidcorrosion fracture surface morphology, to establish and perfect digital analysis modelof the acid corrosion fracture conductivity, study the influence law of theacid-corroded fracture surface interval distribution on the conductivity. To perfect anddevelop the basic research theory of acid fracturing technology, providing guidancefor the design and the effect prediction of acid fracturing process. |
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