Abstract:Because of the abnormal formation stress in Makit area of Tarim basin, the casing creep collapsing in paleogene evaporate bed, low drilling efficiency in Permian volcanic rock, difficult bit selection for complex Paleozoic strata lithology, poor stability of three open hole and high water leakage risk in the Ordovician fractured formation, the research on distributing rules of abnormal formation stress in fault zone, optimization of well profile, high efficient rock breaking technology, blade type impregnated diamond bit, efficient drilling fluid and under- balance drilling technology were made and optimized unconventional casing program design was put forward, high efficient rock-breaking tools and blade type impregnated diamond bit and efficient inhibitive anti-sloughing drilling fluid system were researched and developed. Basing on the above, drilling efficiency increasing technology series was formed, the average ROP of completed well was improved by 17.89% and the drilling cycle was decreased by 34.55%.

Abstract:TLSJD-1 is located in middle-lower Yangtze area. According to the general geology and construction requirements, proper construction organization and scientific and effective construction techniques were adopted. Deflection by screw motor was used for times in the construction to deal with the serious natural whipstocking. With self-developed 5-element drill tool to stabilize hole deviation, drilling trajectory was effectively controlled. In order to solve the instability of hole wall for open drilling of large section of mud shale in deep hole, under the condition of construction water with high salinity, a set of drilling fluid technology was summarized to ensure the smooth progress of the construction.

Abstract:Lost circulation control is the biggest problem in the development process of Fuling shale gas field. According to statistics, different degrees of lost circulation occurred in 67.2% wells during drilling, which has bad affect on the engineering quality, the construction progress and the economic benefit; especially the lost circulation of oil-based drilling fluid in the three opening and long horizontal section, which caused serious economic losses. In order to reduce the risk of drilling engineering, improve drilling efficiency and reduce drilling cost, starting from the actual situation on site, the statistical analysis was made on drilling leakage, it was thought that in middle-shallow layer were mainly karst cave leakage and fracture-cavity type leakage; in Longmaxi formation and Wufeng formation was mainly fracture type leakage. The paper introduces the lost circulation prevention and plugging technologies adopted in Fuling shale gas field according to the characteristics of each opening and the field application. Along with the development region extension, the geological conditions become changing and the leakage is more complicated, the next development direction of lost circulation prevention and plugging technologies are put forward with some suggestions.

Abstract:Along with the continuous shale gas exploration and development in northwest Hunan, the position of drilling technology becomes more and more important. In the drilling process of shale gas exploration well, the well control and blowout prevention have been the most important part in the safety drilling technology. Comparing with the conventional oil and gas, shale gas of northwest Hunan has “three low levels” characteristics of low pressure, low permeability and low saturation, the used well control and blowout prevention technologies are different from those used in oil and gas exploration in the essence. Starting from the source of well control technology, the theory calculation model of formation pressure near shale gas well is established and the corresponding well control technical measures and equipments are suggested. Based on the example of well control in shale gas prospecting well-CY1 in northwest Hunan and the mature conventional oil and gas well control technology, a set of well control technical measures are formulated to ensure safe, saving and efficient shale gas well drilling.

Abstract:The conglomerate develops in Taiyuan formation with high quartz content, which is the main target of Daniudi gas field. In the conglomerate section drilling with PDC, tooth breakage is often caused by big impact load and drilling efficiency is greatly reduced by bit tripping with higher drilling cost. According to the statistical analysis on the data and by the use of GD1306TX and FX55D bits in Taiyuan formation, the ROP is increased to shorten the drilling cycle. It is proved the cost per meter of GD1306TX bit is lower than FX55D bit by statistical cost analysis, GD1306TX bit is more suitable to be applied in abrasive Taiyuan formation.

Abstract:In Tarim basin, Paleogene and Cretaceous strata contain cream and salt with active gas show, cementing is difficult. Based on the summarization on cementing failure causes of anti-channeling slurry with slight expansion latex in early stage, the characteristics of stratum lithology are mainly considered. With the purpose of improving the quality of second interface cementation, the anti-channeling saltwater mud system is selected out. This mud system has the characteristics of small API fluid loss, small SPN value and high cement paste strength. The field application shows the good quality of cementation in cementing process.

Abstract:ZK0401 is a deep hole in the salt rock survey project with designed depth of 3280m. In the coring drilling operation, according to the characteristics of water sensitivity formation, formation pressure and ground temperature, the successful experiment was made by drilling fluid with high temperature resistance and high density saturated salt water drilling fluid matching the suitable core drilling technology, hole terminal depth was 3286m, and the continuous salt rock coring was realized with good effects. The paper introduces the optimization of drilling fluid composition and the drilling fluid technology and measures in detail.

Abstract:The high-pressure formation has attracted high attention in the entire drilling engineering process of high-pressure oil and gas well, and there may be low-pressure thief zones in some of the high-pressure oil and gas wells. In the solidification period of cementing, cement slurry will have weight loss and fluid column pressure in the entire wellbore will be lowered. If the liquid column pressure is lower than the formation pressure in weightlessness well section, the formation fluid will invade the annulus to cause channeling, even lead to well control incidents; if the liquid column pressure is higher than strata (fracture) pressure, the formation leakage will occur, and further cause oil and gas reservoir pollution with less volume cement slurry returning. Therefore, proper handling the relationship between dynamic pressure and formation pressure and the formulation of relevant emergency measures are the key of success in high-pressure oil and gas well cementing.

Abstract:High-performance hydro-hammer adopts the working principle of volumetric double effect; it has the characteristics of single high impact energy and low pump pressure. Laboratory experiments have showed that the structure design of high-performance hydro-hammer is reasonable and the performance and technical indicators have reached the design expectations. The hammer can output single high impact energy and has the characteristics of high impact frequency and low pump pressure also. The field tests have showed that rapid and efficient full face drilling in hard rocks can be realized by the combination of high-performance hydro-hammer and spherical crown button bits.

Abstract:The reverse circulation bit tail of spline DTH hammer is easily broken when drilling into extremely complex strata, such as hard, brittle and fragile ones. The structure design of reverse circulation bit tail was optimized to prolong the service life, and the simulation analysis was conducted on the reverse circulation bits before and after improvement by nonlinear dynamics simulation software LS-DYNA. It shows that due to the high-frequent impact force of hammer, the reverse drill bit tail is prone to having a big local stress concentration which causes fatigue rupture to the bit body. With the optimization of bit tail structure design, comparing with spline reverse circulation bits, the stress concentration of this new-structure bit decreases by 44% and 19% respectively under the conditions of without or with vent duct. Numerical simulations show that the bit service life can be greatly increased by optimization.

Abstract:The silty clay with water content of 13%~27% is frozen at 0 ~-25℃to measures the uniaxial compressive, tensile, shear strength and wave velocity of frozen soil. The test results show that when the silty clay water content is 18%~25% and the temperature of frozen soil is 0~-18℃, along with the increase of moisture content, the compressive, tensile and shear strength of frozen soil decrease under a certain temperature and drillability shows decreasing trend; at certain water content, along with the decrease of temperature, the compressive, tensile and shear strength of frozen soil increase and the drillability grade is improved. For the investigation in winter, the drilling speed can be improved by adding hot water in drilling hole to reduce the influence of frozen soil.

Abstract:Heave deformation and fracture are the common instability form of foundation pit, which is difficult to be monitored. Analysis on anti-heave stability is mainly for the calculation of safety coefficients. The main computing methods of safety coefficient of anti-heave stability include limit equilibrium, limit analysis and strength reduction. An engineering example is adopted in this paper, the above-mentioned methods are used to calculate safety coefficients for anti-heave stability, and the applicability of these 3 methods is comparatively analyzed. The results show that more engineering factors are ignored by traditional limit equilibrium algorithm with too conservative result, which can be modified to improve the applicability. The calculation results are more accurate by limit analysis and strength reduction methods, but further study is needed on failure mode of limit analysis and permitted upheaval value of foundation pit stability in critical state by strength reduction.

Abstract:High pressure jet grouting reinforced cement-soil pile anchor is a new advanced geotechnical reinforcement and support technology. In this paper, combined with 2 engineering cases of retaining pile (SMW or composite piles in row) high pressure jet grouting reinforced cement pile anchor bracing system, it is illustrated that the high pressure jet grouting reinforced cement-soil pile anchor support technology has the advantages of good economic performance, convenient construction and good adaptability with good comprehensive benefits, and the problems of construction in deep soft-clay soil are also pointed out.

Abstract:Soil displacement screw pile (SDS) has been developed on the basis of CFG foundation treatment technology and by the bit improvement, which can reduce the volume of excavated earth and give full play to the bearing capacity of soil between piles to further cut the amount of concrete. The paper first illustrates its working principle of the key structure of the device; then compares the completed project example with traditional process to prove the technical and economic advantages of SDS technology and finally aiming at the produced problems in the process of construction, analyzes the causes and puts forward the treatment measures.

Abstract:By the engineering case, the paper elaborates the application of grouting reinforcement in treatment of backfill subsidence of existed buildings in saline soil area; summarizes the grouting reinforcement method about its design, construction process and quality inspection; analyzes the attentions that should be paid in the design and the application.

Abstract:Three-dimensional finite element model of impregnated diamond bit was established based on finite element analysis software ANSYS/LS-DYNA and the influence of cutting teeth structure on drilling efficiency was analyzed with the field test verification carrying out; a new method for stress area comparison based on Image-Pro Plus was present. The results show that stress concentration appears for concentric ring cutting teeth structure at the front edge of cutting teeth along the rotation direction in initial drilling stage, while non obvious stress concentration appears for saw teeth bit. But different degrees of stress concentration appear at inner and outer diameter edges near the nozzle part for these two kinds of bits in late drilling stage, which may lead to abnormal wear. The saw cutting teeth bits are more efficient than concentric ring ones, but the bit service life is slightly lower.

Abstract:Underground tunnel excavation is still the main way of coal mining, some fracture stratum zones, non cemented soft strata and aquifer on coal seam roof must be encountered in the mining process. If there is misconduct in the excavation, a large amount of formation water may enter along the cracks and through mined-out subsidence areas into the tunnel to cause severe flooding accident, the excavation work will be severely affected, the well lane might be abandoned and even serious personal injury accident might happen. According to the disadvantages of traditional cement slurry, a kind of waterproof has been developed, which is mixed with water at ratio of 1∶1 with rapid condensation and high condensation strength and can be used at the temperature over 25℃. This cement slurry is tested in a mine water plugging operation, the well is 840m in height with outflow of 120m3/h, good water plugging effect is received.

Abstract:The paper introduces an engineering case of accurate blasting demotion of supporting system for foundation pit in Nanjing. The accurate blasting parameters, scientific initiation network and reliable safety protection scheme were presented with good blasting effect.