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钻井中，需要对将要钻达的下部地层深度进行预测，特别是在定向井的钻探过程中显得尤为重要。目前的井斜角、方位能不能满足钻达目标靶区的地质需要，或者地下地质情况（地层厚度、倾向、倾角）发生变化后钻井措施的相应改变，以及需要调整改变的钻井参数怎样确定等，都需要经过严密的计算和分析。文章对钻井轨迹和地质情况进行了分析，从地质层位的小层入手，对构造的走向、倾向、倾角，地层的真厚、铅直厚度，钻井的方位、井斜角、实钻地层厚度等参数进行了分析，在三维空间的基础上，建立了实钻的数学模型，明确了各参数间的关系。推导出的公式适用于包括定向井在内的钻井参数计算，可以在地层钻厚预测、深度对比，钻达目标靶区的水平位移及井斜角、方位角的调整，穿越储层厚度的计算及钻井参数的调整，目标靶区是否在气水界面以内及钻达预想海拔高程的钻井参数调整等多个方面进行运用，这对下步钻井达到地质目的具有重要的指导作用。

Monitoring Calculation of Directional Well with Drilling

In the process of drilling, it is important to predict the drilling formation depth, especially directional drilling. Whether the present deviation angle and azimuth could meet the demand of drilling to the target area, or the drilling measures should be changed in light of the present geological situation (the formation thickness, dip direction, dip) and how to determine the drilling parameters to adjust or change etc. are needed to rigorously calculate and analyzed. Starting with the sub-layer of formation, the parameters of drilling trajectory, geological condition, structural run, dip direction, dip, formation's actual thickness, plumb thickness, azimuth, deviation angle and drilled formation thickness are analyzed in this paper. On the basis of 3-D spatiality, the mathematical model of real drilling is established and the relationships among the parameters are clearly defined. The formulas derived in this paper suit to calculate various drilling parameters, including those of directional drilling, which plays an important role in guiding drilling to the geological target.