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On the basis of the hole-buttom model experiment, this paper studies the damage of mud and cement slurry to foemation. The study shows that the damage of mud is more serious than that of cement slurry. Since the aggressive quantity of cement particles and filtrate is limited by the percolation properties of inner and outer mud cakes and rock core, the damage of cement slurry to formation is therefore decresed. The damage in the area 122 cm inside the wellface is resulted mainly from plugging of grain, while... On the basis of the hole-buttom model experiment, this paper studies the damage of mud and cement slurry to foemation. The study shows that the damage of mud is more serious than that of cement slurry. Since the aggressive quantity of cement particles and filtrate is limited by the percolation properties of inner and outer mud cakes and rock core, the damage of cement slurry to formation is therefore decresed. The damage in the area 122 cm inside the wellface is resulted mainly from plugging of grain, while the damage to the formation 2 cm away from the wellface is resulted from the precipitates of filtrate of cement slurry. This paper also analyzes the pollution depth, the filtrate composition, the quantity of precipitates, and the separation sequence. 本文是在模拟井下实验的基础上,研究了泥浆与水泥浆对地层的损害问题。研究表明泥浆对地层的损害比水泥浆严重得多。泥浆形成的内外泥饼及岩心的渗滤特性,限制了水泥颗粒及滤液进入地层的数量,降低了水泥浆对地层的损害。在井壁1~2cm内,主要是水泥颗粒堵塞造成的损害,而2cm以外的地层则是水泥浆滤液中的沉淀物造成的损害。文章还深入地分析了水泥浆的污染深度,滤液中的成分,沉淀物的数量及析出的先后次序等问题。 This paper analyzed the characteristics of horizontal wells d amage, an d then established a set of method to calculate the drilling fluid lost circulat ion and pollution depth that vary with the horizontal section. Based on the lost circulation characteristics of drilling fluid and law of conservation of mass, by way of Cart model that applies in the fracture fluid lost, the paper came to a mathematics model of drilling fluid lose that varies with the horizontal secti on. Applying the theoretical model... This paper analyzed the characteristics of horizontal wells d amage, an d then established a set of method to calculate the drilling fluid lost circulat ion and pollution depth that vary with the horizontal section. Based on the lost circulation characteristics of drilling fluid and law of conservation of mass, by way of Cart model that applies in the fracture fluid lost, the paper came to a mathematics model of drilling fluid lose that varies with the horizontal secti on. Applying the theoretical model to calculate the equifinal damage depth which varies with the horizontal section, a formula of pollution depth which varies w ith the horizontal section through volume transformation was presented. 分析了水平井地层伤害的特点 ,建立了计算水平井段不同位置处钻井液滤失和污染深度的一套新模型。基于钻井液的浸入特征 ,模拟压裂液滤失情况 ,采用卡特模型 ,根据物质守恒方程可以得到不同井段位置处的钻井液滤失量。采用理论模型计算不同井段位置处的钻井液等效污染深度 ,然后由体积变换得出不同井段位置处的污染带半径 It is important work for reservoir protection to evaluate reservoir pollution level by drilling fluid. It is an economic and effective tool to evaluate the reservoir pollution level directly or indirectly with logging data. Based on experiments, according to the relationship between the permeability damage rate and the every factor of the reservoir, the inherent relation between the indexes of reservoir pollution evaluation is studied deeply, and the quantitative calculating model is developed between the evaluation... It is important work for reservoir protection to evaluate reservoir pollution level by drilling fluid. It is an economic and effective tool to evaluate the reservoir pollution level directly or indirectly with logging data. Based on experiments, according to the relationship between the permeability damage rate and the every factor of the reservoir, the inherent relation between the indexes of reservoir pollution evaluation is studied deeply, and the quantitative calculating model is developed between the evaluation indexes of permeability damage rate, pollution skin factor, pollution depth of drilling fluid, and the parameters of logging, drilling, reservoir physical property and electrical property. With programming calculation and real data analysis, it is found the evaluation method is correct and feasible. And the judge standards of reservoir pollution level by drilling fluid can be derived by the method for a concrete drilling region, which can provide the important basis for scientific decision making of drilling, perforating and stimulating operations in the region. 对钻井泥浆污染储层程度进行评价是油(气)层保护的一项重要工作,若能用测井资料对它实现直接或间接评价将是一项经济有效的手段。文章以实验为基础,从研究渗透率损害比与储层单因素间的关系入手,对储层污染评价指标间的内在关系进行了深入研究,并建立了各评价指标,如渗透率损害比、污染表皮系数、泥浆污染深度与测井参数、钻井参数以及储层物性和电性参数间的定量计算模型。最后通过编程计算和实际资料的处理分析,发现所研究的评价方法正确可行,并可针对具体研究井区给出钻井泥浆污染储层程度的判断标准,最终能为钻井施工、射孔作业以及增产措施的科学决策提供重要依据。
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