地层岩石抗钻特性横向分布规律

Lateral distribution law of formation rock anti-drilling property

地层岩石力学强度分析(含纵向、横向变化规律分析)是石油勘探与开发领域的重要研究方向,对于认识地下圈闭构造、掌握油气生成和运移环境、制定合理油气资源钻采方案等具有重要意义。首先,采集了中国大港油田歧口凹陷东营组、沙河街组地层共27块岩心,测定了抗压强度、可钻性级值等数据,并与对应的测井资料数据开展了相关性研究,建立了分析计算函数;其次,切分各函数不同的相关性系数作为影响权重,再复合于各因素(测井参数)独立的影响规律函数,从而建立对地层岩石强度分析、预测的多因素综合评价函数;最后,将地层岩石强度横向变化规律抽象为一个曲面拟合问题,采用三次曲面幂基函数拟合法建立了映射关系函数,从而形成一种分析地层岩石强度横向变化规律的新方法。研究成果可用于钻井设计中对指定井位、井身轨迹下的地层纵向、横向岩石力学强度及可钻性级值等的分析预测;更可为钻井工程中钻头选型与个性化设计、井壁稳定性评价等提供重要参考依据。

The analysis onformation rock mechanical strength（including the vertical and lateral variation law） is an important research direction in the field of petroleum exploration and development, which is of great significance to the understanding of underground trap structure, the recognition of hydrocarbon generation and migration environment, and the preparation of proper hydrocarbon drilling and production schemes. Firstly, a total of 27 cores were collected from the Dongying Formation and Shahejie Formation of Qikou Depression, Dagang Oilfield to obtain the compressive strength, drillability grade and other data. Moreover, a correlation re- search was conducted in combination with the corresponding logging data, so as to establish theanalytic and computable functions. Secondly, different correlation coefficients of each function were separated and taken as influence weights, and then recombined into the independent influence law function of each factor（logging parameter）, thus creating the multi-factor comprehensive evaluation function for formation rock strength analysis and prediction. Finally, thelateral variation law ofrock strengthwas abstracted as a curve fitting problem. Mapping function was established using thecubic-surface power-function fitting method, so as to develop a new method to analyze the lateral variation law of rock strength. Research results can be used to analyze and predict the vertical and lateral rock strength and drillabilitygrade in the designated well and borehole trajectory during the drilling design. Moreover, these results can even provide important references for bit selection, customized design and borehole stability evaluation in the drilling process.