【作者】 孟庆鸿；

【导师】 王成彪；

【作者基本信息】 中国地质大学（北京） ， 地质工程， 2011， 博士

【摘要】 随着钻探技术的发展,无论是岩心钻探、科学钻探、还是工程勘查皆对岩心采取率及岩心质量提出了更高的要求,因此,现在的取心质量包括岩心采取率和岩心的原状结构程度。本文合松科1井对极松散地层与强塑性松软地层进行了隔液保真取样钻具及防泥包钻头的优化设计,并研究了复杂地层防塌水基泥浆体系。本文分析了在极为复杂地层中钻进岩心采取率极低的原因,得出在极松散地层钻进,钻具内腔的液压力需恒大于或等于内、外腔连通处的液压力;在强塑性松软地层中钻进,依靠布齿形式、排屑空间与水路结构的合理设计与钻进参数的控制防止钻头泥包;为此,开辟了复杂地层取心钻具优化设计的新思路。从取心钻具与水力学特性相互作用的逻辑关系入手,进行取心钻具的结构强度分析,确定了取心钻具结构空间的设计依据;然后结合水力学进行了CFD模拟;泄流槽和钻头内的挡水环是该套钻具的核心技术,能够满足保心效果;仿真分析与模拟试验表明,参数吻合性好;通过对防泥包钻头的CFD模型的分析,得出孔底流场分布均匀、效果良好,具有一定的科学性。优化了螺纹锥度、牙高、螺距、基面距等参数,螺纹强度受钻杆局部内径变化影响显著,内径减小,螺纹整体强度提高;螺纹锥度变化对钻杆强度的影响较大,当锥度达到1:25附近时,螺纹强度最大;螺纹强度随牙高变化极其复杂。随着螺距的增大,钻杆管体螺纹处结构内部应力分布愈不均衡,从而使螺纹的应力集中现象更加显著;螺纹强度随基面距的变化影响不大。结合计算流体力学的基本知识及经验,完成了隔液保真钻具和防泥包钻头的设计和模拟,掌握了其孔底流场分布规律,通过大量的实验测试:结果显示与模拟结果相符。隔液保真钻具的优化结果:仿真分析与CFD模拟试验表明,参数吻合性好,但泄流槽的深度对井底流域的压力场和速度场影响较为明显。50mm槽深井底流速场变化要大,对井底扰动明显,压力梯度较为明显,而70mm深泄流槽的孔底流动相对平缓,可以预测保心效果好,但估计会影响钻速。防泥包钻头优化结果:钻头切削刃前斜面的倾角对孔底流场的分布影响很大,但对孔底压力损失影响不大。钻头在孔底总的压降,30°斜面最高,更容易取心与排屑,25°斜面次之,35°斜面最小。以优化设计的结构参数为依据,分别针对松科一井、内蒙查干温都尔矿区、汶川科学钻井使用的取心钻具进行了优化设计,制造出隔液保真钻具、防泥包钻具;结合工程实际优选泥浆配方,设计了全新测试实验系统,开发了新型简易仪器,测试与观测泥浆的性能,研制松科一井防塌水基钻探泥浆体系。实践证明:两种钻具明显提高了复杂地层中钻进岩心采取率的提高,满足了地质的要求;防塌水基钻探泥浆在松科一井中应用成功,起到了很好的护壁效果;验证了理论设计与优化方案的可行性。更多还原

【Abstract】 With the development of exploration technology, core drilling, scientific exploration engineering and engineering investigation all improve the standards of recovery factor and core quality. This paper, in the light of the ultimate unconsolidated formation and the severely plastic soft formation, conducts optimized design of spacing fluid shape-retained drilling tool sampler and balling-control bit. It also makes researches on the anti-caving water-based drilling mud system in the complex formation based on the Well-1 of Songliao Scientific Drilling. spacing fluidThis paper analyzes the cause of the extremely low recovery factor in the very complex formation, and concludes that when drilling in the ultimate unconsolidated formation, the fluid pressure within the drilling tools should be identically higher than or equal to that of the joint;when drilling in the severely plastic soft formation, the cutter’s distribution,cutting discharge space and the waterway structure should be rationally arranged, and at the same time, drilling parameters should be under control, with the view of preventing bit being balled. Therefore, a new method on the optimized design of core drillings in the complex stratum is put forward.Starting with the logic relationship of the interaction between coring drilling tools and hydraulics, the author analyzes the structure intensity of coring drilling tools, decides the design principles of their structural space, and then conducts CFD simulation based on hydraulics. The sillway and the water ring in the rig are the core of this set of drilling tools, which guarantee the core-protection effect. The simulation analysis and the CFD simulation experiment demonstrate that the parameters have good uniformity. The analysis of balling-conrol bit’CFD mould shows that the down-the–hole velocity field distributes evenly with good effect, which prove its scientificness.Through the optimization of structure parameters, such as the thread taper of drill tools, the tooth height, the pitch of screws and the datum distance, etc. , the author has the findings as follows. The thread strength is greatly influenced by the change of rod’s partial I.D., i.e., when the I.D. reduces, the whole thread strength rises; the rod strength is greatly influenced by the thread taper, i.e., when the taper is near 1:25, the thread strength is at peak; the relation between the thread strength and the tooth height is very complex. As the pitch of screws increases, the inside pressure on screw thread within the rod is unbalanced, thus, the pressure becomes more concentrated; the thread strength is less influenced by the datum distance.With the fundamental principle and experience of Computational Fluid Dynamics, the author finishes the design and the simulation of spacing fluid shape-retained drilling tool and balling-control bit, gets hold of the distribution pattern of down-the-hole drilling fluid field, and proves that the result is the same as simulation after numerous experiments and tests.Simulation analysis and the CFD simulation experiment both indicate that parameters have good uniformity, but the spillway depth affects the shaft bottom’s pressure field and velocity field a lot. The 50mm shaft bottom’s velocity field varies a lot, then the shaft bottom would be easy to be affected and its pressure gradient would be also relatively evident; the 70mm spillway has relatively slow velocity, so its core-protecting effect is predicted to be better, but it may affect the drilling rate. Above findings are got from the optimized result of the spacing fluid shape-retained drilling tool. And the optimized result of the balling-control bit demonstrates that the front bevel angel of bit-cutting-edge affects the velocity field structure a lot, but it has little effect on the down-the-hole pressure. The pressure drop of down-the-hole bit becomes the highest when the angle is 30°,which is the best moment to discharge cuttings. 25°bevel takes the second place, and then the 35°. According to the structure parameters of the optimized design, reinforcement theory and the optimized methods, the author designs the core drilling tools used in the Well-1 of Songliao Scientific Drilling., Inner Mongolia and We chuan satiric wells, manufactures the spacing fluid shape-retained drilling tool and the balling-control bit, and , on the basis of engineering practical optimized mud formula, develops the Well-1 of Songliao Scientific Drilling. anti-caving water-based drilling mud system. It has been found that the 2 kinds of drilling rods could highly increase the recovery factor in the relatively complex stratum, meeting the geological needs. The successful application of anti-caving water-based drilling mud, which acts as a good dado in the Well-1 of Songliao Scientific Drilling., proves the feasibility of the theoretical design and the optimized project.更多还原