提钻取心岩心堵塞形态分析与防堵方法探讨

Analysis of core blockage morphology and exploration of anti-blockage methods in trip round coring

摘要:

取心钻进中常会钻遇含裂隙或破碎地层，岩心进入钻头后由于围压消失，地应力释放导致岩心会沿裂隙碎裂成块，在进入岩心管时形成堵塞形态阻碍后续岩心继续入管，严重时岩心互相对磨消耗，导致岩心采取率不足，地层资料缺失。岩心堵塞已成为取心钻进中影响取心质量和钻进效率的重要因素，岩心破碎状态和堵心形态复杂，钻进中在钻具的动态干扰下岩心堵塞机理难以掌握，使得岩心解堵成为取心钻进中面临的一大难题。本文通过岩心堵塞形态理论模型的建立，从岩心碎裂后在岩心管内形成的典型堵塞形态和变化规律进行分析，对易堵心地层的取心参数规程提出建议，并根据所列举的典型岩心堵塞形态对防堵方法进行研究与探讨。

Abstract:

During core drilling， it is common to encounter fractured or fragile formation. When the core enters the drill bit， due to the disappearance of confining pressure and the release of geostress， the core will break into blocks along the fractures. When entering the core tube， it forms a blockage form whcih hinders the entry of the subsequent core into the tube. In severe cases， the core will wear and consume each other， resulting in insufficient core recovery rate and the missing of formation data. Core blockage has become an important factor affecting core quality and drilling efficiency in core drilling. The state of core fragmentation and blockage morphology are complex， and it is difficult to grasp the mechanism of core blockage under the dynamic interference of drilling tools during drilling， making the core unblocking a major challenge in core drilling. By establishing a theoretical model of core blockage morphology， this paper analyzes the typical blockage morphology and variation patterns formed in the core tube after core fragmentation， suggestions on coring parameter specifications for formations prone to blocking are posed， and based on the typical core blockage patterns listed， the anti blockage methods are put foward and discussed.