Abstract:The comb-like multi-lateral hole is one of the main technical methods for coalbed methane mining. Study of the distribution of cuttings under different conditions in the horizontal hole, which works as the mother hole of comb-like laterals, can be used as an important basis for the selection of drilling parameters. Based on FLUENT fluid dynamics simulation software, the paper analyzes the effects of drill string rpm, drilling fluid viscosity, annulus velocity, debris concentration, debris particle size and borehole eccentricity on the cuttings-carrying capacity in horizontal holes. The result can provide a scientific basis for rational selection of drilling parameters during the drilling process.

Abstract:According to the geological environments where the geothermal resources occur, hydrothermal geothermal resources in Henan Province can be classified into 3 types: subsidence or sedimentary basin, piedmont basin and mountain uplift. High heat temperature sources from convection heat transfer in deep mega geotectonics and heat conduction in intrusive rocks formed pore, fissure and karst geothermal resources through heat exchange with Neogene, Paleogene and Paleozoic shallow groundwater. During the 14th five-year Plan Period, the exploration and development of hydrothermal geothermal resources in Henan is mainly focused on karst heat storage at depth of 1800 to 4000m. This will bring a new challenge to geothermal drilling engineering. According to formation characteristics and experience, it is proposed that deep geothermal drilling should follow the general principle of “eco-friendliness, high quality and efficiency, safety and health”. In regard to formation characteristics and drilling requirements, the drilling process will be selected in the order of priority as below: first, air drilling (pneumatic DTH hammer, air-lift reverse circulation, positive air circulation core-drilling); second, drilling fluid + air (air-lift reverse circulation); and finally, drilling fluid (rotary + PDM); thus achieving the compound drilling method with multiple drilling processes in one well.

Abstract:Well Zhetongdi-1 is a shale gas geological survey well deployed in Baijiang Town, Tonglu County, Zhejiang Province. The well is aimed to explore the gas-bearing properties of the shale gas new strata of the Ordovician Hule Formation and Ningguo Formation in the Lower Yangtze area by taking cores and logging wells. The article describes in detail the basic conditions of the well, the drilling process and the well deviation treatment method. When the depth was 140m, the well deviation was serious and exceeded the specification by 9.3°; thus, it was plugged and was re-drilled. Through optimum combination of drilling parameters such as weight-on-bit, rpm, and pumping volume, and use of the bottom jet bit with concentric pointed teeth, well deviation caused by the strong deflecting formation was eliminated with maximum deviation of 5.5°, meeting design requirements.

Abstract:Oil shale (shale gas) Well Sanye1 in Xinjiang Santanghu Basin was designed with depth of 1750m and full hole coring. In the drilling process, there were some problems such as wellbore contraction, collapse and drilling difficulty in winter, and so on. Through the adoption of the polymer film-forming mud system, special coring drilling tools and other technical measures as well as specific drilling management measures, the drilling technical problems have been effectively solved. It provides high quality physical data for the investigation and evaluation of oil and gas resources in this area.

Abstract:With an underground horizontal well in the underground roadway connected to the original surface extraction “U” type well, CBM surface extraction can be converted to the underground positive pressure extraction, which can eliminate many disadvantages of surface extraction of coalbed methane, help to reduce extraction cost, and improve extraction management. At present, for coal mine gas treatment, negative pressure drainage with atmospheric pressure boreholes is adopted, where in the process of drilling, the original formation pressure in the coal seam is reduced rapidly, leading to gas channel damage due to compaction effect. In order to solve this problem, the comprehensive coalbed methane extraction technology and application were investigated in Baode Coal Mine, where underground drainage at positive pressure was used. This method can effectively improve the final gas recovery; thus, providing a new way to reduce the extraction cost of Baode Coal Mine. The method is worthy of extensive popularization.

Abstract:In recent years, the directional drilling technology for Ordovician limestone water control grouting has developed rapidly, leading to sharp increase in the number of multi-lateral ultra deep horizontal grouting holes. In drilling of horizontal grouting holes, there are many common problems, such as large amount of formation leakage, sudden mud loss, long open hole sections at small-diameter, complex hole trajectories of the horizontal section; great difficulty in control, strict error allowance, expensive directional instruments and tools, etc.; and relatively high drilling risk due to proneness to drill pipe sticking incidents. Once the sticking incident occurs, it will take a long period to deal with it with great difficulty. The traditional sticking treatment method doesn’t work well for such incidents in horizontal grouting holes. With use of the air compressor, compressed air was supplied to destroy the sand settling structure in the horizontal hole, and blew the settled sand out of the hole or into the formation fractures; thus realizing successful treatment of sticking and burial in drilling of horizontal grouting holes. The preventive measures for sticking and burial incidents in drilling of horizontal grouting holes are summarized.

Abstract:Comparing with conventional trenching exploration and rotary drilling, geological soil sampling by percussion drilling has the advantage of high core recovery, high sampling quality and less damage to the environment. A portable percussion drill rig was designed with continuous improvements made through the analysis of the impact principle, the design of the drilling tool and the analysis and calculation of the structure of the pipe puller multiple design verifications, and twice field trials. Practice has proved that the percussion sampling drill rig can work with high efficiency with hi-fi soil samples, which can meet the technical requirements of high-quality soil sampling works.

Abstract:In light of low reliability, high drilling cost and environmental pollution with diesel driven deep drilling rig, this paper puts forward an energy-saving and environment-sound upgrading scheme for transforming the drilling rig from traditional diesel-drive into electric-drive. Industrial power grids was directly used as power supply to optimize the power drive system of the drilling rig. Extensive application in deep well drilling such as geothermal wells oil wells, has proved that the upgrading from diesel drive to electric drive has resulted in energy saving and environmental protection, and improved the reliability, superiority, economics and safety of drilling rig operations, achieving the desired purpose.

Abstract:Based on limit equilibrium theory in three-dimension, the pullout uplift bearing capacity of circular anchor plates in loess under the loading which is vertical to the plate surface is studied. The study considers the equation of loess failure around anchor plates, normal stress and shear stress on the failure plane and buried depth rate h/D when the plates are being uplifted. It is found that the pullout uplift bearing capacity increases with the buried depth, and will reach the limit when the buried depth reaches a certain value. When h/D=1 to 2, the overlying soil weight puts slight effect on pullout uplift bearing capacity; when h/D=4, suction between the soil and the anchor plate contributes more than the overlying soil weight to the results; what is more, in the case of h/D>4, the overlying soil weight plays a decisive role in the pullout uplift bearing capacity. The comparison between the theoretical calculation and the test results of other researchers demonstrates that the theoretical results show consistency with the test results; thus verifying the correctness of the theory. It provides a valuable reference for the design of pullout uplift anchor plates.

Abstract:The foundation pit support for the miners’ apartment building of Huangling Mining Group is designed with the excavation depth of 8.37m. Since the security level for the south side is classified as the first grade, and slope grading is not permitted, the soldier pile + prestressed anchor grid is designed for support. For the east, west and north sections, the security level is classified as the second grade, and sloping is permitted; thus, slope grading+the soil nail wall support is designed for support. For dewatering, tube wells outside the pit is combined with the water ditch collection and drainage in the pit. The design of different support and dewatering plans are introduced. At the same time, the construction specifications for soil nailing walls, support piles, prestressed anchor cables, dewatering wells and observation wells are introduced.

Abstract:This article describes the foundation pit dewatering case of the underground support project of the Comprehensive Passenger Transportation Hub in the East of Yangzhou, where step-slope excavation is adopted as well as diaphragm wall and inner support in the foundation pit excavation. Since the aquifer is thick and highly permeable, deployment of the dewatering wells, either at the bottom of the slope or the inter-slope platform, will directly affect the dynamic control of dewatering. In this paper, two dewatering plans are proposed for comparison: in Plan 1, wells are arranged at the slope bottom; while in Plan 2 wells are arranged at the inter-slope platform. Comparison results from the numerical simulation method show that: in Plan 1, although the number of wells and the final total flow rate are slightly smaller than the those in Plan 2, the need to pre-dewatering will result in a large amount of water waste; in Plan 2, the pumping well number can be gradually increased with the depth of the excavation, reflecting the principle of dewatering on demand. Therefore, Plan 2 is considered to be better. This research can serve as a reference to the dewatering design of similar foundation pits: not only shouldthe total number of wells and the final total flow rate be considered, but also the different excavation stages. By implementing the principles of dynamic control and dewatering on demand, the green construction of foundation pit works can be realized from the very start.

Abstract:The approach to selection of the design of the foundation pit support system for a project in Jingzhou is introduced. The geological conditions of this project are poor and the surrounding environment is extremely complicated. The SMW method was adopted through calculation of the internal force and deformation of the support structure with Tianhan Software based the elastic resistance calculation model, and verification of the foundation pit anti-uplift, anti-overturning, overall stability, etc. Comparison of the calculation results with the foundation pit monitoring data showed that use of SWM piles as the support structure provides a reasonable design and economics, and ensure the safety of the foundation pit and surrounding buildings. It is the first application of the SWM piles used in the Jingzhou foundation pit support project, and it has obtained significant social benefits.

Abstract:Taking the deep foundation pit support project of a commercial center in Nanchang as an example, on the premise of ensuring safety, various factors were taken into account to reduce the cost of foundation pit support through analysis of the surrounding environment, geological conditions and excavation depth. In the control of groundwater, water cutting-off was combined with dewatering to control the water table outside the pit at the properly designed elevation. The composite support structure was adopted for foundation pit support with the soil nailing wall and tensional anchor piles used for different parts. Various design alternatives were compared and optimized to attain safety, applicability and proper economics.

Abstract:With the Wangshan Village landslide as study subject, and with regard to the static anti-sliding stability in the project, indoor and field tests were conducted to analyze and evaluate the intrinsic factors affecting the stability of the Wangshan Village landslide, such as geological structures and site engineering conditions. The commercial software ABAQUS was used then to compute the model for slope reinforcement with anti-slide piles. The safety factors for the bottom pile, middle pile and top pile on the slope have been calculated and obtained. The calculation results show that the middle pile has the highest safety factor with 1.58. In view of the stress concentration at the foot of the slope under the static load and the acceleration amplification effect at the top of the slope under the dynamic load, the upper pile position and the lower pile position were designed around the middle of the slope, and the safety factors of two new positions were calculated. The results show that the safety factors of two positions are fairly high. Finally, comparison of the safety factors of five different pile positions on the slope has verified the feasibility of the upper pile and the lower pile, and the results can be taken as reference for the engineering works.

Abstract:A 35m high reinforced concrete water tower with the conical structure, located at Shuangbai Road, Caohang District, Minhang District, Shanghai, is surrounded by Pioneer Park and overhead pipelines, etc. Since the surrounding environments in the blasting area is relatively complicated, the collapse direction is limited, and it is also difficult to accurately control the collapse direction of the water tower, the blasting flying rocks and blasting vibration. In view of the structural characteristics of the water tower and the surrounding environmental factors, the isosceles trapezoidal blasting gap was made with a pre-cut triangle directional window, which played a decisive role in the accuracy of orientation; meanwhile, the passive protection method of laying yellow sand and straw bags, combined with the active protection method of the bamboo fence and safety net effectively controlled the impact of blasting vibration and flying rocks on the surrounding area, achieving good results.