【作者】 李玮；

【导师】 李士斌；

【作者基本信息】 大庆石油学院 ， 油气井工程， 2006， 硕士

【摘要】 目前确定可钻性指标的方式是在室内通过测试岩石试样的力学性能,或模拟真实钻进条件用微钻头来研究可钻性指标,微钻头法测定结果符合程度高,但由于室内试验滞后于实际钻进,费用高,周期长,妨碍钻井速度的提高。为解决以上问题,本文引入分形理论,对岩屑粒度分布、分形维数等特征进行分析,进而提出一种用岩屑粒度分布分形维数来确定可钻性级值的测试方法,简称分形法。由于该方法以井底返出岩屑为研究对象,可以边取样边测定,实现随钻随测,从根本上解决了传统取心法的滞后性、费用高等缺点。通过对上返岩屑进行标准化处理,很好地排除不同破岩工具、不同钻井液条件等对上返岩屑粒度分布的影响。试验表明:岩屑质量分布曲线具有良好的线性,相关系数在0.85以上,标准化破碎后的岩屑粒度分布具有更高的相关性(在0.96以上),这说明上返岩屑粒度分布是分形的。岩石可钻性计量标准是通过在室内进行岩石的微钻头可钻性试验确定的,若建立分形维数与微钻头可钻性级值的关系,即建立了分形维数与岩石可钻性的关系。试验结果显示:分形维数与微钻头可钻性级值的回归相关系数为0.7227,由此制定了一个基于岩屑粒度分布分形维数表示的岩石可钻性预测指标。经取样检验,分形法测定误差波动在2%-11%之间,整体平均值为6.5%,可见分形法描述岩石可钻性级值具有很高的精度。更多还原

【Abstract】 The active way to fix on the rock drillability needs to test mechanics of the rock sample withlaboratory experiment, or simulate the actual condition and use the micro bit method to researchthe drillability index. Although the test result with the micro bit method has a high coincidence,the laboratory experiment lags to the actual drilling, has the more expenses and the longer cycle.So it disturbs the improvement of the drilling speed.In order to solve these problems, the article propounds a kind of test method to fix on the rockdrillability classification number with the fractal geometry principle;the abbreviated name of themethod is the rock drillability fractal graduation. Objecting to the drilling cuttings returned frombottom hole, the method can test and catch sample simultaneously. In this way, it can not onlycomplete test while drilling, but also can radically solve the flaws of coring posterity and highcost. Through dealing with the upward debris standardly, the method can commendably removethe influence that different break rock implements and drilling fluid conditions have effects onthe upward debris’ grain grade distribution. The experimentation indicates that the debris’ massdistribution has a good linearity. The regress correlating modulus is above 0.85 and the debriswith standard broken has the higher pertinent (above 0.96).Based on these data, we can concludethat the upward debris’ grain grade distribution is fractal.Through doing the micro bit experiment in the laboratory, we ascertain the measurementstandard of the rock drillability. If we establish the relationship between fractal dimension andthe microbit drillability grade, we will establish the relationship between fractal dimensionand rock drillability. The test result indicates that the regress correlating modulus between fractaldimension and microbit drillability grade is above 0.7227. According to the result, we constitutethe predicting index of the rock drillability which based on the fractal dimension of the debrisgrade distribution. After sample examination, the error fluctuates between 2%-11%, and theoverall mean value is 6.5%. It is obvious that it has very high precision with the fractal methodto describe the rock drillability grade.更多还原