Abstract:In order to further find out the extent and severity of the impact of a large abandoned industrial and mining site to the soil and water environment, detailed quality investigation of the soil and water environment at the site (including the affected area) was carried out to find out the pollution status of soil and groundwater in the “starting area” with risk assessment, as well as preliminary solutions and suggestions for land use. A total of 386 soil and water environment sampling boreholes were designed with the drilling workload of 4180m. Undisturbed samples of soil and groundwater were required at designated locations to determine the key parameters such as stratum structure, aquifer structure, rock and soil mechanics, as well as the vertical pollution characteristics, pollution depth and groundwater environment quality of the soil at the site. In order to ensure the quality of the project, the Geoprobe series direct push drilling rig from Kejr Branch of Geoprobe Systems (Geo-Exploratin system Company) of USA was adopted. Water-free soil sampling was carried out by static pressing or hammering with or without tripping the tool, and temporary water samples were taken by static pressing or hammering, which effectively solved the problems of insufficient sampling quantity, sample disturbance and pollution caused by sand liquefaction and sand gushing from boreholes. This study introduces and analyzes the equipment, drilling tools, technological methods and applications.

Abstract:In the Yan’an National Terrestrial Shale Gas Demonstration Zone, there are problems such as low mechanical drilling speed, long drilling time, which directly affects exploration and development of terrestrial shale gas at low-cost, high-efficiency. Increasing the drilling speed is important means to shorten the drilling time and reduce the drilling cost, and it is also a direct indicator of optimum and fast drilling. This paper analyzes the rock mechanical characteristics of the terrestrial shale formation, and carries out theoretical research on three aspects: optimizing the drill bit, optimizing the drilling mechanical parameters and hydraulic parameters so as to enhance the adaptability of the drill bit to the formation, and improve the wellbore cleaning ability and the drilling speed. As a result, the key drilling technology suitable for the development of terrestrial shale gas horizontal wells has been developed with 3 horizontal wells successfully completed in the demonstration area. The drilling time was shortened by 11 days, and the horizontal drilling rate increased by 120.08%. It has achieved optimum and fast drilling of horizontal wells for terrestrial shale gas and is worthy of promotion.

Abstract:With the deepening of exploration and development, the completion depth of the ultra-deep well during the final stage cementation has exceeded 7400m. The complex geological structure and variety of borehole structures bring many quality control difficulties for cementing. Liner cementing has the characteristics of “two highs, one small and one low”, that is, high risk of leakage, high working pressure, small displacement of slurry and low displacement efficiency, leading to incomplete displacement of slurry during cementing. Through a field case of application of cementing technology in Shunbei Oilfield, this paper investigates the method to improve the cementing quality under the condition of incomplete displacement, so as to improve the cementing quality in this block and increase the service life of oil wells.

Abstract:The difficulty in casing running needs to be solved urgently for extended reach wells in Bohai Oilfield. Taking a well A in Bohai Oilfield as an example, this paper analyzes the technical difficulties in φ244.5mm casing running from the design point of view, and analyzes the factors affecting casing running using the software of LANDMARK. The results show that if the kick off point becomes shallow, the surface casing running depth becomes deeper, and the hold angle is over large, then less casing unit weight, reduction in the friction coefficient, and increase in the floating section will lead to reduction in casing running friction, and increase in the casing hanging weight. By optimizing the above parameters, the φ244.5mm casing running plan was designed with the floating manner with the length of the floating section as 1200m. The relative error between the predicted value and the measured value of the casing hanging weight was 6.34%, which was within the allowable engineering error range. The casing running design process has been developed for extended reach wells in Bohai Oilfield. In the casing running design, the kick off point, the surface casing running depth, the case weight, the friction coefficient and the floating section should be considered comprehensively to optimize the running plan to ensure successful casing running.

Abstract:Dawenkou Basin is rich in rock salt resources which are deeply buried. The overlying strata are loose mudstones and sandstones of Paleogene, which are easy to soften in water and difficult to drill through. Shandong Feicheng Haijing Salinization Co., Ltd. implemented a one million ton/year brine recovery and transmission project with seven units of brine supply wells, each with depth of about 3000m. Well intersection requires high-precision kick-off and continuous build-up. This paper introduces a field case where the key drilling technology for well was used for well intersection, and the MWD system for directional trajectory control with detailed description on how to drill in rock salt formation, the application of mud motor drilling tools, kick-off from the fixed-point and other key technical measures so as to provide reference for brine supply well intersection drilling.

Abstract:The geological conditions in Shanggong Gold Mine, Luoning, Henan Province are complex, where the strata are broken; in particular, the middle and lower parts are eroded into green mudstone, and will be dispersed, flaked, and collapsed when encountering water, making it difficult to drill. In view of the characteristics of the strata in the mining area, measures have been taken in aspect of equipment and material selection, borehole structure and drill bit selection with emphasis on application of the film-forming drilling fluid to solve the difficulty in coring. Remarkable results have been achieved, and some experience has been accumulated for drilling the complex strata in the future.

Abstract:The Songnan oil shale formation in the Songliao Basin is highly water-sensitive, which is prone to be hydrated, spalled, and even collapsed during drilling. With use of the S95+5 wireline coring process, and optimization of the borehole structure, bit type, drilling fluid and drilling parameters, the difficulty of protection of borehole walls in oil shale formation was successfully solved, achieving engineering quality requirements. This paper summarizes the key technologies in wireline coring in oil shale formation so as to provide technical reference and guidance for the similar drilling works.

Abstract:In order to ensure underground coal mine safety production, systematic analysis and research has been conducted on precise exploration drilling technology. According to the geophysical prospecting results of the 230m belt gateway at Working Face-3110 in Sangshuping Coal Mine, the exploration boreholes were designed for the abnormal water-rich area, and the regional exploration test was carried out by using MWD drilling combined with conventional rotary drilling. The test results in Sangshuping Coal Mine showed that the precise drilling technology allowed flexible deployment of exploration boreholes in space to explore the abnormal water-rich area in the underground coal mine; meanwhile the area of the geophysical abnormal region can be effectively deduced to avoid the water inrush and flooding accident in the larger water-rich area, ensuring safety of the No.11 gateway in Sangshuping Coal Mine. It can provide technical support for the detection of geological abnormal areas in coal mines and guarantee the safe production of coal mines.

Abstract:The MK-3 well was drilled for investigation and evaluation of potash resources in the Mesozoic salt basin in southwestern Yunnan with the design depth of 2700m, full hole coring and the core diameter not less than 80mm, the core recovery more than 80% over the non-ore bearing section, and more than 95% over the ore-bearing section. The technical requirements were demanding and it was difficult to drill. During drilling, problems such as stratum collapse, water gushing, stone falling and salt rock dissolution were encountered. The drilling task was successfully completed by adopting measures such as magnesium chloride saturated brine drilling fluid, coring with HXY-9B drilling rig, reaming with TSJ-2000 water well drilling rig, multiple tiers of casing for staged sealing off. The well was completed at depth of 2701m with average core recovery rate 90%, and 98.65% over the ore-bearing section. The final hole diameter was 127mm, and the core diameter was 81mm. Geophysical well logging indicated that each index has met the design requirement. It breaks the record of drilling depth by CHD127 standard wire coring drill pipe for “P size” in China.

Abstract:The characteristics and applicable conditions of PHC pipe piles and CFG piles are discussed. Based on the engineering geological conditions at the construction site of the Escort Center of the Zhengzhou Aviation Port Economic Comprehensive Experimental Zone, analysis is made of the problems with separate use of PHC pipe piles, the CFG pile composite foundation and bored cast-in-place piles. In regard to the geological condition and the load condition of the building, the feasibility and rationality of selecting the combination of the PHC pipe pile and the CFG pile are discussed. This paper introduces the construction technology and optimization of the PHC and CFG composite pile for the Escort Center project. The application results and the problems encountered are analyzed with the approach to solve the problems put forward, which has produced good returns.

Abstract:The combination of multiple support methods is more and more widely used in current foundation pit support. For the foundation pit project of No.1516-36 plot in the third phase of Fengtaiyuan east area of Zhongguancun Science and Technology Park, Fengtai District, Beijing, the pile anchor is selected for overall support in combination with soil nailing wall plus large rate sloping, large sloping anchor spraying plus cantilever piles for local support according to the actual requirements. The third-party monitoring results of the foundation pit by the relevant surveying and mapping units are all within the safe deformation range, meeting the design requirements.

Abstract:The main pier cap of Zhuhai Honghe Bridge is located in the flow silt area of the Xijiang River Basin of the Pearl River, and the steel sheet pile cofferdam is used for the foundation pit support. During the excavation of the foundation pit, the steel sheet pile cofferdam was obviously deformed. After detailed analysis, it was found that the main causes for the accident were significant decrease in the mechanical properties of soil due to continuous rise of the groundwater level, insufficient length of the steel sheet pile in the side span, excessive concentrated load on the edge of the foundation pit, and insufficient construction accuracy of the support system. In order to ensure the safety of deep foundation pit support, the reinforcement measures for the steel sheet pile cofferdam were adopted in regard to the actual condition through comprehensive analysis of the causes for the deformation of the steel sheet pile cofferdam, including extension of the steel pipe pile cofferdam into the muddy soil laye, strengthening of the internal support system, which were continuous monitored during the construction process. Finally, the foundation pit construction was completed safely.

Abstract:The scientific drilling borehole CSDP-02 in the Eastern Sea of China was completed at 2843.18m. The borehole needed to be expanded after completion to carry out subsequent research. Before expansion, the 114 mm casing needed to be pulled out; however, the casing cannot be pulled out as usual due to resistance caused by borehole failure. In this research, the hydraulic internal cutter technology was adopted to cut the stuck casing section by section, and increase the pull-out length of stuck casing per run. With this method, casing sticking was solved economically and efficiently. The detailed operation procedure and key points are presented through the field case.

Abstract:There are some safety risks such as exposure of the mountain, vegetation damage, soil erosion, rolling dust, geological hazards due to the irregular exploitation of mineral resources and quarries. The state and local governments at all levels attach great importance to the ecological restoration for mines. In the ecological recovery and management for mines, traditional treatment for high and steep slopes from mining is mainly slope grading; that is, the slope is trimmed from the top to the bottom, and then the platform and the slope are greened. However, with this method, there is some construction difficulty, and a large amount of work due irregular mining operations; meanwhile, it will further damage the ecological environment, and it takes a longer time to cover the slope with green plants. In view of these circumstances, a new type of technology called “shotcrete floating platform for the restoration of the mining environment” (in short “shotcrete floating platform”) was innovatively developed. Field experiments demonstrated that it solved the technical difficulty in high steep slope treatment for ecological recovery at the mines and quarries, and reduced additional destruction of the ecological environment with simple and rapid construction, and quick effect; at the same time it provided effective control of geological hazards.

Abstract:Hot dry rock (HDR) is a kind of clean energy resource emerging in recent years. It is buried in the deep earth (below 3000m), without or with little water or water vapor, and the temperature is over 180℃ with very low permeability. Unlike conventional hydrothermal systems, the utilization of HDR needs to build Enhanced Geothermal System (EGS), where the fluid circulation must be stimulated artificially. At present, the study on HDR is in the early stage, and the theory on the heat source, the heat reservoir, the formation mechanism, the burial mechanism etc. is not complete. The development of HDR also faces a lot of problems such as reservoir stimulation, high temperature drilling technology, monitoring while drilling. In the world, there is a very large reserve of HDR, and it is recognized as a high-quality clean energy by the international society; However, little research has been done on HDR, and the high development difficulties need continuous accumulation of knowledge and technology. From the perspective of scientific popularization, this paper lists the current research status and problems about HDR so as to make HDR more popular.