PDC钻头泥页岩地层钻进泥包机理及对策研究进展

PDC钻头发生泥包时,切削齿和钻头体上会黏附大量的泥页岩切屑,影响破岩效率,弄清泥包机理是了解泥包影响因素、预防和清除泥包的前提。为此,通过调研、分析近年来国内外PDC钻头泥页岩地层钻进泥包发生机理、防止和清除泥包等方面的大量文献,从钻井液类型及性能、钻头结构、钻头水力学参数和PDC钻头其他处理等4项技术方面,总结论述了预防和减少PDC钻头泥包的新成果、新方法和新动态。进而认识到:①从微观层面研究泥页岩岩屑与钻头表面的黏附机理是研究泥包机理的未来方向;②通过向水基钻井液中添加化学添加剂以使其具有油基钻井液的性能的方法具有可取性;③预测泥包的钻头结构参数和水力学参数的确定需要大量的实验研究;④建立井底流场特点与钻头泥包的量化关系是今后数值模拟的研究方向。

Bit balling mechanism and research progress in countermeasures for PDC bit drilling in mud shale formations

Massive mud shale cuttings will adhere to cutters and bit body when PDC bit balling occurs, which affects rock breaking rate. To clarify PDC bit balling mechanism is the prerequisite for summing up influence factors and studying the methods and measures of preventing and eliminating balling. In view of this, from a collection of the relevant literatures at home and abroad, we summarized new achievements, methodologies and trends in the research of prevention and mitigation of PDC bit balling in four aspects, including drilling fluid type and property, bit structure, bit hydraulic parameters and other processing of PDC, on the basis of bit balling mechanism, countermeasures and application. On this basis, the following research directions in this field were proposed. It will be a trend to research the adhesion mechanism between the shale cuttings and bit from the microscopic point of view and to establish the quantitative relationship between the downhole flow field and bit balling. The method will be considered available in letting the water base drilling fluid present the oil base drilling fluid′s property by adding some chemical additives. Massive experiments will be necessary to determine the bit structure parameters and bit hydraulic parameters for the prediction of bit balling.