Abstract:Many deep buried super long tunnels are designed for the SichuanTibet Railway line, and most of them are located in high altitude, high steep slope and no man mountain zones above the snow line, where the terrain is steep and undulating, and the traffic conditions are poor. Horizontal directional drilling along the tunnel axis provides an effective method for tunnel investigation. In view of the engineering and geological characteristics, this paper provides a 3000m capacity horizontal directional drilling plan for super long tunnel investigation in terms of equipment and technology. The hole profile is specified in the plan together with full face drilling and coring drilling technology, drilling fluid measures and some measures for complex situations. With less amount of drill work, the plan provides more detailed physical geological data for tunnel investigation, hence the true characterization of the geological conditions in the tunnel.

Abstract:In view of drilling string wear and low drilling efficiency at total loss of return in deep or horizontal geological drilling, a kind of high efficiency drill pipe grease was developed with the one step method with white oil, sodium based thickener and adhesive material as raw materials, and has achieved remarkable results from field use in horizontal holes along the Changdu section of SichuanTibet Railway, which strongly supported the construction of large displacement horizontal holes on the SichuanTibet Railway. Indoor evaluation and application results showed that the grease has low temperature resistance (-16℃), easy application, good adhesion and lubricity, and high cost performance ratio. It can protect drilling tools for a long time, and its lubricating effect can compares to that of foreign products.

Abstract:Many problems were encountered in tunnel engineering investigation for the SichuanTibet Railway project, such as large workload, great resistance to drilling tools, large drilling distance, great drilling difficulty and high down hole incident rate. The existing technology cannot meet the requirements of horizontal hole drilling of the tunnel project. Based on full investigation of the present status of horizontal hole drilling technology in petroleum, coal and geological exploration industries, this paper analyzes the movement law of rotation and vibration of the wire line core drilling tool for horizontal hole drilling in tunnel exploration, and the critical load calculation formula is developed for the ultimate bending moment with the drill pipe at both the buckling and the critical bending state. The friction resistance on the drilling tool is studied by numerical simulation.

Abstract:The SichuanTibet Railway is located in the southeast of the QinghaiTibet Plateau. Due to the development of tectonic activities, the rock mass is loose and broken with well developed fractures and confined water; thus, complex situations such as hole collapse, falling stones, stuck drilling, and lost circulation often occur during the exploration of these formations. In view of the problems of hole wall instability and lost circulation during the drilling of the directional horizontal holes designed for the formation along the tunnel exit section, a suitable drilling fluid system for the hole was proposed through analyzing the formation characteristics and leakage in the hole. Then, orthogonal experiments were carried out to quickly obtain the optimal combination of the adding content of the sealing materials. The follow up field application results verified that the improved drilling fluid worked well. Therefore, the drilling fluid with the optimized formulation can greatly reduce the incidents in the holes, effectively promote the exploration progress, and obtain significant economic and social benefits.

Abstract:Borehole DZShen021 at SichuanTibet Railway is a tectonics investigation hole where the stratum is very complex. During drilling, water gushing, sand gushing, falling stones and borehole shrinkage occurred. The high density drilling fluid was researched and used to balance downhole pressure to prevent mud and sand from flowing into the drilling string, so that the inner tube of the core barrel can be landed in place smoothly. Through selection and concoction of the strong inhibitive and low water loss drilling fluid, borehole collapse and shrinkage in mudstone were reduced. The drill bit diameter was also increased, hence the annulus to allow drilling cuttings to be discharged smoothly; thus the circulating pump pressure can be reduced, which was conducive to the stability of the hole wall in the fault gouge section. The screen pipe was used over the broken section to divert some water inflow so as to reduce the damage to drilling fluid performance. By strengthening the control of drilling parameters, disturbance to the borehole wall was reduced and the borehole wall was maintained as stable as possible. Finally, the borehole was drilled to the designed depth, achieving the purpose of engineering investigation.

Abstract:Green exploration is the embodiment of the new development concept in engineering investigation. As the most direct means of various engineering investigation methods, drilling is absolutely necessary; however, it also brings about many environmental problems. Through analysis of drilling features and possible environmental problems in engineering investigation, and in combination with actual drilling experiences and research, the drilling solutions for green engineering investigation were put forward and applied in SichuanTibet Railway investigation. The problems remained with current green engineering investigation are considered and concluded. It is advocated that the companies of investigation, design, construction and the relevant departments work together to establish a comprehensive green engineering investigation system.

Abstract:The blowout preventer is closed immediately once the oil or gas well overflows or blows out. During the well shut in period, the blowout preventer will withstand the water hammer pressure generated by shut in. Based on the analysis of the physical characteristics of water hammer propagation in shut in wells, this paper derives the formula for calculating the direct shut in pressure from water hammer. With comprehensive consideration of the factors affecting the water hammer velocity such as gas content in the wellbore fluid, gas liquid two phase flow pattern, solid phase type, the calculation formula of the propagation velocity of the water hammer wave in the three phase mixed fluid of gas, liquid and solid is deduced with the influencing factors of the water hammer wave velocity analyzed through an example. Calculations show that the water hammer wave velocity is very sensitive to changes in the gas content: when the gas content in the drilling fluid is 0～0.001, the water hammer wave velocity changes abruptly. The water hammer wave velocity is only 385m/s when the gas content is 0.001, indicating a decrease by 67% compared with that in the pure drilling fluid; while the solid phase content in the drilling fluid, the inner diameter and the wall thickness of the casing have less influence on the propagation velocity of the water hammer wave.

Abstract:In the regional geological survey project in Qingxu County, Shanxi Province, scientific drilling holes of 800m, 2000m and 3000m are designed to fill the gap in delineation of the Cenozoic floor burial depth, with each hole completed 30m drilled into the bedrock. Full hole coring is required with the core recovery rate ≮85%, the core diameter ≮60mm, and the undisturbed rock sample to be taken with the plastic protective tube. In light of the difficulties such as ultra deep soft soil layer, unknown characteristics and thickness of each group, unknown drilling depth, large diameter high fidelity full hole coring, far lower contract price than the current market cost, with the 800m hole drilled with “water well drilling rig +conventional coring +long open hole section”, and a 640m parametric hole drilled with “core drill+ wire line coring + casing cementing”, an innovative process of “water well drilling rig + wire line coring + long open hole section” was then developed and used to complete the 2000m hole. The core recovery of the hole reached 93%, and the borehole diameter and deviation met the geological requirements, which lays a solid foundation for the smooth construction of the 3000m hole and provides experience and reference for similar projects.

Abstract:In geothermal well drilling in Lankao where the depth of the second well section is more than 1500m, the common bentonite drilling fluid system can not meet the requirements, and it is easy to cause sticking incidents. In order to solve the drilling problems, a kind of low solid phase, high lubricating and double polymer drilling fluid system was designed for geothermal well drilling. Field application in 4 wells showed that the drilling process was smooth, which effectively solved the problems such as poor sand carrying capacity, unstable well wall in mudstone formation, large water loss in sandstone formation, thick mud cake, etc. None of the 4 wells met any difficult situation and incident. The drilling results indicate that the drilling fluid system has good compatibility with the formation characteristics in the Lankao area and can meet the needs of drilling works, providing good guidance for geothermal well drilling in the Lankao area.

Abstract:During detailed coal exploration drilling in the extended area of Huacaotan Coal Mine, Shandan, Gansu, problems such as mud production, borehole expansion or shrinkage, caving and falling blocks in mudstone formation were often encountered. In light of the above problems, drilling fluid technology research was carried out. Materials as silicone inhibitor, filtrate reducer, plugging while drilling materials, and coating and flocculation materials were chosen for research on drilling fluid formulation and properties. Through indoor experiments and field applications, it has been proved that the drilling fluid has good inhibiting performance, anti caving and wall protection performance and rheological properties, and effectively solves the above technical problems. The service period of the drilling fluid is greatly increased; thus significantly reducing the discharge of waste drilling fluid, and fostering the application of the concept of green exploration in the exploration area.

Abstract:In order to provide drinking water for more than 10000 people in Nongchang Village, Chengguan Town, Xincheng County, and divert water for irrigation of arid farmland in the karst rocky mountain area, feeding holes and curtain grouting holes were drilled in the lower reaches of the No.3 opening at the Fuliulang depression over Longguang Underground River, Xincheng County, Guangxi. Crushed stone aggregates were dropped through the feeding hole; then cement mortar or cement slurry was poured into the curtain grouting hole to consolidate the crushed stone aggregates to build the seepage proof curtain to block the underground river course which flows through the Fuliulang depression, which successfully intercepted the discharge of Longguang Underground River to the downstream, and reduced the leakage of water from the depression to the downstream through surface openings and underground caves; meanwhile increasing water overflowing from surface openings to the depression. As a result, A depression reservoir with the capacity of about 2.5 million cubic meters was built, resolving the difficulty in drinking water for more than 10000 people in Nongchang Village, Chengguan Town, alleviating the irrigation of dry farmland, and improving drinking water conditions for local villagers.

Abstract:The electric blast shock wave has great application potential in increasing permeability and removing plugs of oil and gas reservoirs. In this paper, ANSYS/LS[CD*2]DYNA software is used to investigate the influencing factors of electric blast shock wave induced cracks through variation of the in situ stress, elastic modulus and tensile strength. The simulation results show that the in situ stress has a strong inhibitory effect on crack propagation. Under action of the two way isobaric in situ stress, the shape of the crack zone is circular, and with increase of the in situ stress, the fracture degree and fracture radius of the rock mass decrease gradually. Under action of the bi directional unequal compressive in situ stresses, as the difference between the horizontal principal stresses increases, the direction of crack propagation gradually changes from circular to elliptical, exhibiting the characteristic of extending along the direction of the maximum horizontal principal stress. The elastic modulus has important effect on crack initiation: with increase of the elastic modulus, the fracture degree and fracture radius of the rock mass increase. As the tensile strength increases, the fracture degree and fracture radius of the rock mass decrease.

Abstract:The compact drill bit is the key of the DTH hammer percussion compact drilling technology. Its structure directly affects drilling efficiency, pore forming quality and application effect. Nonlinear finite element theory was used to analyze the changing laws of elastoplasticity and compressibility of soil under dynamic load. The result showed that: the phenomenon of piling effect is produced by conventional drill bits in the process of percussive compaction drilling is the main reason for the decrease in drilling efficiency. In order to overcome the influence of the pile effect, ANSYS/LSDYNA was used to perform numerical simulation analysis on the drilling process of stepped drill bits and cam spinning drill bits, and verified by actual drilling experiment. Both the numerical simulation analysis and the experiment results showed that the cam bit can effectively avoid the rebound problem of the soil during the drilling process and reduce the influence of the pile effect on the drilling efficiency. The experimental results are in good agreement with the simulation results, indicating that the numerical simulation results are relatively reliable.

Abstract:Vibration drilling or tube sinking/compacting machinery is widely used in construction works but the systematic analysis of the influence of the frequency ratio on vibration tube sinking machinery power is also lacking. Furthermore, the driving power sometimes increases abnormally, and how to calculate it still perplexes engineering designers. In this paper, the average power and instantaneous power of inertial and non inertial excited vibration machinery is calculated and analyzed with the damping dissipation power method. The results show that, the dissipation power of the inertia excited vibration system is approximately proportional to the square of the excitation force angular frequency in the whole frequency range for large damping (0.5＜ ζ ＜1). For small damping (damping ratio ζ ＜0.5), only in the resonance range the power is proportional to the square of the excitation force amplitude and inversely proportional to damping. Moreover, it is the small damping that causes abnormal power increase. Non inertial excitation machinery can only absorb enough power when working near the damped resonance range. During the design of vibration tube sinking machinery, not only is it necessary to meet the average power requirement of the system, but also to verify the maximum instantaneous power requirement.

Abstract:LGZ series full hydraulic multi functional pile rigs are featured of three patented technologies, i.e. axial sliding kelly bar, large torque hollow rotary power head and double drum synchronous hoist. They have the technical advantages of construction safety, multiple functions, stable and efficient transmission. This paper introduces the performance parameters and technical characteristics of this series of pile rigs, and their application in construction of five types of piles, including screw pile, screw displacement pile, cement soil mixing pile, CFA pile and large diameter CFA pile. It has been proved that LGZ series full hydraulic multifunctional pile rigs can meet the construction requirements of various pile foundation construction methods and can be extended to application of other construction methods.