Abstract:A wide range of fracture zones and water-rich areas commonly exist along the axis of the tunnel in the long and deep buried tunnels of water conservancy projects， the management of pre-grouting by more than 1000 meters of ground horizontal directional drilling can achieve a good effect of the surrounding rock reinforcement and gushing water blocking， which has been a successful attempt in the water conservancy industry. This paper introduces the successful experience of drilling ultra-long horizontal directional pre-grouting holes with screw drilling tools in a project. The difficulties and problems are discussed such as cutting removal， coping with the problem of “back pressure”， measurement while drilling system in strong magnetic field， measures of green exploration， as well as the insufficient adaptability of drill， low efficiency of hard-rock drilling， and the influence of grouting on drilling operation， etc.， and the contermeasures are also posed. 4 main holes and 6 branch holes were constructed， along which the longest hole is 1427m， and the drilling workload is 8737.89m. The implementation of the project proves that the current directional drilling technology has the ability to drill accurately over long distances， which can provide a guarantee for the pre-grouting and ahead-treatment in the complex strata of the ultra-long tunnels and the related drilling projects.

Abstract:Natural gas hydrates is a new type of energy， characterized by huge reserves， cleanliness and high efficiency. China is rich in hydrate resources， and the safe and efficient exploitation of hydrates can help realize the transformation of energy structure and the strategic goal of “double carbon”. Hydrate reservoirs are generally characterized by non-rock formation， weak cementation and strong temperature and pressure sensitivity. The application of water jet technology to hydrate drilling process can effectively solve the engineering problems of well borehole collapse and formation destabilization caused by conventional methods. This paper summarizes the existing water jet drilling hydrate technology and water jet drilling tools， and analyzes the influencing factors and breaking mechanism of hydrate-containing sediment breaking process under the impact of water jet. Finally， the research direction for the application of water jet technology in the hydrate drilling process is prospected. This work can provide support for the research of natural gas hydrate development technology in China.

Abstract:During the drilling process， accidents of screw drilling tools breaking and falling often occur. For lightweight falling objects caused by accidents such as detachment of the outer shell of the screw drilling tool and core pulling due to rotor fracture， the applicability and success rate of using conventional slip salvage barrels are insufficient. Based on this， a screw drilling tool three slip eccentric fishing barrel was designed， which drives the upper， middle， and lower slips to contract and clamp the conjugate annular space through the conical guide surface of the fishing barrel， achieving effective fishing of this type of falling objects. The eccentric arrangement structure design of the three slips increases the effective clamping area and improves the comprehensive fishing force of the fishing barrel on the screw drilling tool. Based on the working principle of the fishing barrel， a calculation formula for the conventional clamping force of the slip and the squeezing clamping force was established. By comparing， it was found that the conventional clamping stress of the slip required for the three eccentric fishing barrel can be reduced by 50.46%， and the bite depth of the fishing tool can be reduced by 13.92%. The trial produced fishing tube has been put into salvage practice on the construction site， indicating that its structural design is reasonable and its salvage performance is reliable.

Abstract:The self-excited vibration rotary percussion drilling technology can improve the rock breaking efficiency and the ROP.The application test in a test well located in the northern part of the Jizhong region were presented.The drilling diameter of the test well section is 215.9mm， and the BHA is PDC bit+ZJXC-178 self-excited vibration impact tool. The field application tests are carried out in two well sections， the test drilling section and the subsequent well section. Through a meticulous analysis and comparison of torque， bit usage， ROP and cuttings in the same well and adjacent well， the self-excited vibration rotary percussion drilling technology significantly improved the drilling speed， achieved the speed increase effect of up to 73.4%， and the footage of a single bit also increased by 48.2%.The effectiveness of this technology in improving drilling efficiency is verified. While ensuring the rock breaking cutting force of the bit， the sudden change of torque is effectively reduced， and the stick slip vibration of the bit is significantly inhibited， so as to achieve speed increase and protect the bit at the same time.

Abstract:Shale gas formation have developed fractures and poor cementation， manifested as rock fragmentation， poor water sensitivity， and low wellbore strength. During the drilling process， it is easy to encounter complex situations such as collapse， falling blocks， and diameter reduction， which can lead to instability of the wellbore， drilling jamming， and buried drilling accidents inside the hole. Research on deep exploration drilling technology for the geological survey well engineering of the shale gas geological survey project in Liuzhou， Guangxi， and the application of PVA1788 film-forming system without solid flushing fluid and film-forming anti collapse system without solid flushing fluid， rope coring fluid dynamic hammer drilling technology， new technology for expanding corrugated pipe wellbore protection， and directional drilling correction technology for screw drilling tools. Good construction effects have been achieved in a number of field applications.

Abstract:Currently in the field of deep geological core drilling，wire-line core drilling is the most commonly used drilling technology. Owing to annular size of wire-line core drilling is smaller， have no choice but to adopt the method of enlarging the drill bit， solve problems such as high pump pressure and high excited pressure causing hole-wall instability. In deep hole construction， the problem of annular clearance can be solved by increasing the drill bit to the upper caliber without lowering the upper casing. There is also an additional level of spare caliber. This article analyzes the drill pipe capacity of wire-line coring drilling， The theoretical basis for cross bore wire-line coring tools is proposed. The drilling tool has been designed and processed in a complete set and continuously improved in application practice. It provides great help for drilling structure design and complex formation drilling in the field of deep geological core drilling， Achieve good application results. In order to meet the requirements of long hole coring in geothermal drilling， a design scheme for large diameter wire-line coring tools was proposed， further expanding the scope of use of wire-line coring.

Abstract:Non-contact face seal has a stable operation and no direct friction between the faces， which can greatly extend the seal life and has a wide application prospect as a shaft seal for various rotary machinery. Non-contact face seals are designed with a configuration on the face to produce a hydrodynamic pressure effect to improve the load carrying capacity of the seal. This paper describes the influence of groove shapes， face deformation， temperature-stick effect and cavitation effect on the hydrodynamic pressure effect of face seals， summarizes the current research status on the theory， experiment and application of hydodynamic pressure effect， and prospects the future development direction of non-contact face seals.

Abstract:In response to the drilling challenges such as poor wear resistance and corrosion resistance of aluminum alloy drill pipes and the difficulty of drilling in hard strata， the effects of basalt fibers on the properties of 7075 aluminum alloy drill pipe materials and WC-based diamond composites were investigated in this paper. The aluminum matrix composites and matrix were prepared by powder metallurgy and hot-pressing sintering， and their properties were tested. The results showed that the mechanical properties and corrosion resistance of basalt fiber/7075 aluminum matrix composites were improved compared with 7075 aluminum alloy. The basalt fibers reduces the wear ratio of the matrix， improves the density and thermal conductivity of the matrix， and increases the force of the matrix holding the diamond. This paper also summarizes and outlooks the research on the application of basalt fibers in the field of casing and oil pipe. The research on the application of basalt fiber in the field of casing and tubing is also summarized and prospected in this paper.

Abstract:It takes a lot of time to go out to change the bit in geological drilling construction， and there are certain safety risks， which greatly affects the drilling efficiency. Using the drilling technology of replacing the bit without lifting the rod can solve this problem well. Using the 95 specification wireline coring drill pipe as the platform， the basic structure of BH-75 drill pipe was used， and in view of the existing problems， the BH-95 specification drill pipe without lifting drill bit change was developed. At the same time， the BH-75 drill pipe was improved according to the specific structure of the 95 specification drill pipe， so as to improve the bearing capacity and convergence （delivery） stability of the drill pipe， and automatic sand removal mechanism was added. The technology was applied in the Taodi 1 well （geothermal well） in Yichun City， Jiangxi Province. The drill bit was changed without lifting drill at the hole depth of 680.65~704.25 meters. The success rate of drilling tool in place was 100%， the core recovery rate reached 99.4%， the core quality was good， and the tripping times were reduced to a minimum， effectively preventing the hole accidents caused by tripping. The drilling technology without lifting drill Bit Change provides timely optimization of drill bit usage plans， reducing energy consumption， effectively protecting hole wall safety， and reducing labor intensity for drilling in formations with strong abrasiveness， slipping， and frequent alternation of soft and hard in deep hole geological exploration.

Abstract:The torque impactor can convert the kinetic energy of drilling fluid into high-frequency circumferential kinetic energy of the lower drilling tool， thereby eliminating stick-slip vibration， protecting PDC drill bits， and improving construction efficiency. During the construction of two geothermal wells in Baise， Guangxi and Bijie， Guizhou， due to the influence of soft and hard interlayers， the stick-slip vibration effect was strong， causing the composite pieces of PDC drill bits to quickly collapse and the drill bits to be scrapped in advance. A composite drilling process of torque impactor + screw drilling tool is used. By reasonably designing the drilling tool combination and drilling parameters， compared with the simple screw drilling process， due to the effective control of stick-slip vibration， the phenomenon of tooth collapse of the drill bit composite piece is significantly reduced， the service life is increased， and the average mechanical drilling speed is increased by more than twice， Overall construction efficiency and economic benefits has been improved. It provides a new solution for the construction of formations prone to stick-slip effects such as soft and hard interlayers.