Study on Mechanical Data Logging for Small Diameter Drilling using Neural Network Techniques

在地下采矿中，在开挖和建造支架之前，获取有关岩石结构的信息，包括不连续面的分布，是很重要的。钻机在工作面上的机械数据，如扭矩、推力、转速和冲程，对了解地下结构是有用的。为此，进行了室内试验和现场试验，研制了一套机械数据录井系统。1.通过室内实验发现，钻机扭矩或推力的大小反映了岩石类型的差异，地层与裂缝的分离在扭矩/推力比或扭矩/钻井速度每转记录中表现为一种特定的模式。2.作为神经网络技术的一种算法，采用自适应共振理论(ART2)和反向传播网络(BPN)从钻机的力学数据中提取岩层边界和裂缝对应的模式。利用这两种算法，先后成功地估计出了不连续面的位置。3.在现场实验中，在便携式钻机上安装了数据采集系统，用于采集力学数据。利用该钻机在某煤矿井下进行了可行性研究。4.结合野外实地测量的多组测井资料，重建了含不连续面的地层的二维结构。从这种结构可以估计出不连续面的方向，这是很难从仅从一个钻孔获得的测井数据来评估的。

In underground mining it is important to obtain information about the rock structure, including distribution of discontinuities, before excavation and constructing supports. Mechanical data from a drilling machine at the working face such as torque, thrust, revolution and stroke can be useful for understanding the underground structure. Therefore, both laboratory and field experiments were carried out in order to develop a mechanical data logging system. A data analysis system using neural network techniques was also developed for objective interpretation of the logging data and to display the log of strata and discontinuities.1.From the laboratory experiments it was found that the level of torque or thrust of a drilling machine reflected the difference in rock types, and the separation of strata and cracks appeared as a specific pattern in the log of torque/thrust ratio or torque/drilling speed per one revolution.2.As an algorithm of neural network techniques, adaptive resonance theory (ART2) and back propagation network (BPN) were employed to extract the pattern corresponding to a rock layr boundary and cracks from mechanical data of a drilling machine. Using both algorithms sequentially the location of discontinuities were successfully estimated.3.For the field experiments, a data acquisition system was attached to a portable drilling machine for the collection of mechanical data. A feasibility study was conducted using the drilling machine at an underground coal mine. It was confirmed that the discontinuity log estimated by the analysis conformed to the core sample reconstructed from borehole TV data.4.Combining several sets of the logging data measured at a local area in the field study, a two-dimensional structure of the strata including discontinuities was reconstructed. From this structure it was possible to estimate the orientation of discontinuities, which was difficult to evaluate from the logging data obtained from only one drill hole.