Abstract:Duringdrillingofthe3000mscientificboreholeintheShuiwangzhuangMiningArea, theproperandoperablepreventionmechanismandmeanshavebeendevelopedwithcarefulmanagement,overallplanningofthedeepholedrillingtechnology, logisticssupport,equipmentandtools,andverificationofthefeasibilityofthedrillingplan. Technicalclearancemeetingshavealsobeenmaderoutinetoreducetheauxiliarytimeandreducetheprobabilityofaccidents.Atlength, thetreatmentmethodsandsolutionsforcomplexformationaccidentsaresummarizedsoastoprovidereferenceforthesimilarcase.

Abstract:Maintaining wellborestabilityinunconventionalgas wellsis muchimportanttotheexplorationand productionofnaturalgasincoalＧbearingformationinthesouthwesternregionofGuizhouProvince．Thispaper investigatesthewellborefailuremechanismincoalandmudshaleformation,andfindsoutthatthetwokindsof wellborefailuremechanismsareessentiallydifferent．Inaddition,solutionsforwellboreinstabilityareinvestigated intermsofchemistry,mechanicsand mechanicscoupled withchemistry．Influenceof wellboreinstabilityon wellＧradiusvariationsandcorerecoveryisanalyzedinthecontextofaCBM wellinZhinaCoalfield,leadingtothe findingthatwellboreenlargementisgreaterwithlowercorerecoveryoverthecoalＧmudstonesection．Predicting accuratelytheformationpressuresofexploration wells,optimizingthedrillingfluidsystem anddensity,and choosingtherightdrillingtechniquescontributetoCBM wellborestabilityinthesouthwesternregionofGuizhou Province．

Abstract:In order to solve the problem that the cooling source of conventional gas hydrate hole-bottom freezing sampler is difficult to be stored for a long time and the core freezing efficiency is low, an external cooling source freezing sampling method is proposed. The cooling source is stored in the fishing device, which reduces the storage time in the hole and improves the storage efficiency. During the freezing process, nitrogen is injected into the freezing chamber to enhance the convection of heat transfer between cooling alcohol and core and to improve the core freezing efficiency. Low temperature alcohol（-130℃）, a mixture of liquid nitrogen and alcohol，is used as a cooling source. Cooling source storage test and core frozen experiment are carried out in this paper. During the procedure storing 30-minute cooling source, the frozen energy storage rate is 73.1%. The thermal efficiency between cold source and core is improved because the nitrogen is injected in the cooling source, the average temperature of the core drops to 14.9i2℃, the freezing efficiency is increased by 24.3% compared with the traditional way.The problem that the cooling source cannot be stored in the drill pipe for a long time can be solved by adopting the cooling source external sampler structure. The problem of low core freezing efficiency can be solved by passing nitrogen into the cooling source to increase the convection of heat transfer. This paper provides a feasible method for Natural gas hydrate sampling.

Abstract:Guanzhong Basin in Shaanxi is rich in geothermal resources which has a high degree of development and utilization. Geothermal drilling is the main means for geothermal exploitation; however many problems are often encountered in drilling operations, including borehole collapse, mud production from clayey soil, drill bit balling, deterioration of drilling fluid properties, lost drilling tools. This paper analyzes the causes of these problems by examples, and discusses the prevention and treatment measures.

Abstract:During drilling directional and horizontal wells, the effect of trajectory control quality of the vertical section on the trajectory control of the following directional section is usually neglected. In domestic requirements on the quality of trajectory control, the effect of displacement, inclination and azimuth on the following trajectory control of the directional section is not given necessary attention. For directional and horizontal wells, the deviation in the vertical section not only jeopardizes the trajectory control and completion operations, but also bring negative effect on the well deployment in the oilfield; meanwhile, it may lead to well collision in the vertical section of wells from the same platform. This paper analyzes the deviation results of directional and horizontal wells completed in recent years, and describes the reasons why these deviations were formed. Based on that, this paper further analyzes the effect of the deviation and gives the proposal to deal with it.

Abstract:Air lift reverse circulation drilling has obvious advantages for lost formation. But through the comparison of positive and reverse circulation drilling processes at several sites, it is found that there is the obvious weakness of easy breakage of drilling tools in reverse circulation compared with direct circulation. In order to guide drilling operations, give full play to the advantages of reverse circulation and eliminate the weakness of reverse circulation, the stress of drilling tools in the hole is analyzed with summarization of the causes for easy breakage of drilling tools in reverse circulation drilling. Subsequent drilling has verified that breakage of drilling tools were effectively reduce.

Abstract:In the top fill cementing process in karst strata with large leakage, the cement slurry is easy to be diluted due to the displacement fluid or changes in the stable liquid level. If it happens during the injection of the displacement fluid, cementing will fail; and if it happens after the injection, the cement slurry may not rise to the annulus of the overlapping casing or be diluted without forming the cement plug due to many factors. This paper summarizes the key technology of the top fill cementing process in view of the setting location of the drill string, and changes in the stable liquid level during and after slurry water injection. Based on the field cases, some artificial control methods are proposed to improve the success rate of cementing.

Abstract:In view of the problems such as shallow borehole depth, low rates in borehole completion, presence of blind drainage areas in the broken-soft coal seam, it was proposed to use the comb type directional boreholes in the floor for long-distance and regional gas drainage and control in light of the occurrence characteristics of the coal seam, its roof and floor strata in Qinglong Coal Mine, Guizhou Province. Firstly, the construction principle and technical advantages of the comb directional boreholes on the floor were analyzed, and the design principles of the comb directional borehole on the floor were summarized from the selection of borehole target layers, kick-off point and borehole spacing. Through the optimization of drilling equipment, drilling technical parameters and drilling tool combinations, the fractured coal seam and rock along the borehole were drilled through successfully, and the 127mm casing protection boreholes were run in the hole. Several comb directional boreholes were completed in the floor at No. 21605 bottom drainage roadway. The gas drainage effect shows that the gas drainage flow rate is large, the concentration is high, the attenuation rate is slow, the single borehole drainage concentration is 60%～85%, the drainage purity is 0 .8 to 1.5m3/min, achieving high-efficiency gas drainage. The study provides an important reference for regional gas drainage and control in the broken-soft coal seam.

Abstract:With the continuous development of conventional oil and gas resources, its stock resources are becoming less and less. The successful development of unconventional oil and gas resources in the United States has laid the technical foundation for shale gas exploration and development. Reservoir reconstruction technology is one of the two key technologies to determine the success or failure of shale gas development. The brittleness index of shale gas reservoirs is a key indicator for evaluating the shale gas reservoirs that can be modified (fracturable). In this paper, extensive and in-depth research on shale gas reservoir brittleness evaluation methods at home and abroad is carried out, and various mechanical characterization methods of rock brittleness and the influence of mineral composition on rock brittleness are summarized. That provides basic reference materials for the study of shale gas reservoir brittleness evaluation methods in China.

Abstract:In order to ensure the safe and smooth drilling of Well Longtan X3, the first directional well to be drilled in bed rock, a lot of calculation has been done in the drilling engineering design with the Landmark software on the well structures, BHA, bit optimization, drilling fluid optimization and borehole cleaning to cope with the tricky issues such as circulation loss, well deviation and wellbore instability, poor drillability of hard rocks, difficult borehole cleaning; at the same time, statistical analysis and screening were made for optimizing of the engineering design. As a result, drilling operations have been carried out successfully without any accidents, indicating that the engineering design was proper, and the technical difficulties in drilling operations can be overcome.

Abstract:The exploitation of coal mines has brought great benefits to the development of the national economy, but it has also caused many environmental geological problems, especially in the process of coal seam mining, where the fracture channel formed by deformation and failure of the overlying bedrock in coal seams is prone to mine gushing (figure) water accidents, threatening the lives of underground workers at any time. In this paper, taking the 051505 working face of Lingxin Mine as the research object, the height of the water flowing fractured zone in the overlying bedrock in the No.14 main mining coal seam is simulated by using the Flac3D numerical simulation software. The simulation results show that when the mining thickness of the coal seam is 2.5m, the maximum height of the water flowing fractured zone is 59.5m. At the same time, the empirical formula method is selected to calculate the height of the water flowing fractured zone. Finally, the results obtained by borehole measurements are compared with the first two methods. The numerical simulation results are in good agreement with the measured borehole results. It is concluded that the numerical simulation method can achieve the purpose of predicting the height of the water flowing fractured zone efficiently, simply and reasonably. It also provides some reference for the safety and green production of the similar mines.

Abstract:In the process of shield excavation of the water intake tunnel for a power plant in the south of Jiangsu, the confined water flooded the tunnel with sediments due to a gas kick. It was necessary to prevent the confined water from surging out again during the tunnel repair. Whether the water level of the massive confined aquifer under the Yangtze River can be reduced by the tube well caused a great controvesy. Base on the analysis of hydrogeological conditions and field pumping tests, the hydraulic connection between the objective aquifer with the river water and the lower massive confined aquifer was found, the hydrogeological parameters of each layer was calculated, a reliable dewatering scheme was provided, and the subsidence deformation was predicted and analyzed. It also has solved a series of difficult problems such as the construction of pipe wells over water, providng important reference of similar projects.

Abstract:The seafloor template is one of the important equipment for offshore drilling and sampling. It is used for wellhead positioning, drilling tool guiding and clamp stabilization, and wellhead monitoring. It can also be equipped with other tools for cone penetration test, coring, logging, etc. The seafloor template is a device that integrates machinery, hydraulic system, optical fiber communication, and electrical automation. It consists of mechanical structure, hydraulic system and control system. With the working requirements of the seafloor template in mind, this paper proposes a seafloor template control system including drill pipe clamping, video addressing, image acquisition, wellhead information monitoring, etc. The control system, as the core equipment, includes the power distribution system, the photoelectric measurement and control system, and the underwater hydraulic power station.

Abstract:This paper introduces the performance parameters of the CYS-300 full hydraulic geothermal well drilling rig, the design of key mechanical components and the design of the hydraulic system. The rig selects the gear pump as the power component of the hydraulic system, and cooperates with the hydraulic multi-way valve to realize the confluence of the hydraulic oil of the power head dual hydraulic motor and the actuator for the intake cylinder, and realizes the series-parallel operation of the power head double hydraulic motor through the hydraulic control two-speed valve. The output of four kinds of speed and torque can simplify the design of the hydraulic system, reduce the energy loss of the hydraulic system, and reduce the maintenance and use cost while meeting the design requirements of the drilling machine performance parameters. The drilling rig adopts the three-chain double-speed mechanism of the oil cylinder to realize the feeding and lifting of the power head, and has the advantages of simple structure, reliable performance, strong impact resistance and stable lifting. The application of on-site engineering shows that the CYS-300 full hydraulic geothermal well drilling rig has stable and reliable performance, strong application ability in process and complex stratum, safe and comfortable operation and high drilling efficiency.

Abstract:The Fenhe Bridge pile foundation along Menghua Railway has such characteristics as large diameter, great borehole depth and complicated stratum. Many problems have been encountered in the construction such as borehole shrinkage, higher-than-standard settlements, rebar cage dislocation. By careful analysis and exploration, the method of mud preparation, the treatment measures of borehole shrinkage in expansive soil, and the effective tools to prevent dislocation of rebar cages have been developed for drilling in loose sand layers with rotary drilling rig, which not only ensured the construction quality, but also reduced the cost, achieving some social and economic benefits.