Abstract:The geological structure of the beibu gulf basin oilfields in west Nanhai is complex. Down-hole incidents are frequent in well drilling and completion. In order to cope with the increasing difficulties in the marginal oil field drilling, such as wellbore collapse, multiple faults, formation leak, drill pipe sticking, difficult reserve protection, etc. in the Weizhou formation in this area, a novel full oil-based drilling fluid formula was developed through laboratory compatibility experiments based on the ratio of each drilling fluid component. Comparison of full oil-based drilling fluids with conventional oil-based drilling fluids indicate that the full oil-based drilling fluids have stronger sealing and plugging, inhibition, good lubrication performance, strong anti-pollution ability, good wellbore cleaning and good reservoir protection. It can also effectively increase ROP and solve many problems with the conventional oil-based drilling fluid, achieving a comprehensive drilling efficiency.

Abstract:Green exploration is the only choice to achieve both resource and ecological protection. With the application of shallow drilling technology to geological mapping in thin overburden of the desert steppe in Middle-East Inner Mongolia, a shallow drilling technical system based on green exploration has been preliminarily summarized in this paper, including combination of portable drilling equipment and tools, environment-friendly drilling fluid, drilling and well logging together; replacing trenching with drilling; construction organization and management. Meanwhile, some insufficiencies with the system has also been discussed. The system will contribute to the development of green exploration technology.

Abstract:Core jamming is susceptible in drilling difficult formation, compromising the coring footage per run and core drilling efficiency seriously. In this paper, with examination and sorting out of various core jams in drilling difficult formation, the properties of core jamming formation are summarized with core jamming causes analyzed. And then the measures to prevent core jamming are presented in terms of coring bits, coring tools, properties of drilling mud and core drilling processes.

Abstract:During the drilling and well completion process, sticking often occurs when casing is run into the horizontal section during RIH of casing, and in some extreme cases casing may be tightly stuck. It is much more serious in western Sichuan due to relatively complex geological conditions. Analysis of some typical sticking cases and their causes leads to the following conclusion: there are 2 main types of sticking: sudden sticking and sticking due to increasing resistance; and the relevant improvement measures are put forward.

Abstract:Circulation loss has been a technical challenge in drilling work. It is always a key point to find effective and quick solutions to circulation loss in drilling in the Ruoergai uranium mining area under different working conditions. Large circulation loss was encountered in drilling the ZK4-5 borehole with gravity falls of the drilling string for several times, and cement plugging was done with little effect. Under the condition of the limited borehole diameter, the slim corrugated tubing was adopted to deal with the large circulation loss formation successfully, providing reliable technical support for sealing large circulation loss formation.

Abstract:The key technologies for drilling in goaf were elaborated in the construction of ventilation holes by raise boring in the slow inclined shaft in Laoshidan coal mine. In view of the characteristics of large diameter ventilation holes passing through the goaf, deep wells and large diameters of the shaft, the large diameter raise boring process was adopted; the pilot holes were drilled with wireless directional drilling technology, and then the orientation technology of non-magnetic single point inclinometer DTH hammer was followed; the special treatment of the pipe bottom was carried out by the technical casing isolation method to ensure the smooth lifting of the technical casing; cementation of free casing and the large diameter casing artificial flexible bottom were also employed, etc. The large diameter raise boring technology is comprehensively introduced, with the problem and achievements in the raise boring process summarized. It has a demonstration effect for similar construction.

Abstract:The drill string is the most important connecting link in deep exploration, and it is prone to experience failure due to complicated loads with long time working in wellbores full of drilling fluid, corrosion, wear, temperature and so on, leading to great economic loss. Investigation has found that vibration is the main cause of drill string failures; however, besides vibration, drill string failures are also caused by other factors, such as drill string quality, human acts, wellbore quality, running in of casing, inclination measurement, drilling fluids in deep geological drilling. This paper proposes the corresponding preventive measures for these influencing factors. It is emphasized that with the increase of deep geological drilling depth, geological drilling string dynamics research will become more and more important, and should be strengthened to ensure the smooth progress of deep geological drilling with all round consideration of influencing factors for geological drilling string failures.

Abstract:During geo-technical investigation, rock formation with different weathering degrees, and bouldery formation with different particle sizes and cementation can be encountered in drilling of the same borehole. The complexity of geological conditions may easily lead to such phenomena as bit bouncing, bit balling, resulting in low core recovery. To improve the adaptability and drilling efficiency of diamond bits, two kinds of diamond bits with heterogeneous structures were designed and manufactured according to the characteristics of geotechnical investigation. In the heterogeneous structure, every single cutter is divided into two parts: main and auxiliary working layers, which allows the diamond bit behaving like both the PDC bit in rock fragmentation and the impregnated diamond bit in drilling, improving the adaptability of the diamond bit to different formation. Field testing indicates that the new heterogeneous diamond bit can achieve 2.68m/h average rate of penetration, and 48.7m average bit service life in weathered rock and bedrock. Compared with ordinary electroplated diamond bits, the rate of penetration is improved by 21%, while the service life is more or less the same.

Abstract:In this paper, a new multi-stage surface set diamond bit was developed to solve the problem of low drilling efficiency in very hard rock and mudstone interbed in the coal seam gas pre-survey area in Jincheng and Huoxi, Shanxi. Compared with the sharp cutting tooth PDC drill bits previously developed and other manufactures’ drill bits, the ROP has been significantly improved with good drilling results in this area.

Abstract:Sudden water inrush encountered during operation of the open-type TBM may lead to dangers, and then grouting of sealing slurries is often the main means to control the geological disaster. On the basis of analyzing the shortcomings of the existing slurries, the formula of the sealing slurry suitable for open TBM method was developed, and then was optimized by orthogonal tests. The final formula is as follows: water cement ratio 0.59, tartaric acid 0.25%, hydrolytic polyacrylamide solution 3% and sodium aluminate 1.6%. Under the condition that the controllability (pumping period, etc.) met the requirements, the properties of the optimized formula, including water precipitation, compressive strength were tested and the laboratory simulation test was also done. The stone developed from the orthogonal tested formula provided good compressive strength and impermeability, meeting the needs of the field. The pump can stop in a short time after injecting the controllable slurry at the inflow point. Compared with the traditional slurry, the amount of slurry used for plugging leakage can be greatly reduced. The results show that the controllable formula has a good control effect on the water inrush danger encountered in construction of tunnels in the province, and can meet the actual construction needs.

Abstract:The surrounding ground settlement in the process of the foundation pit construction is directly related to the safety of the surrounding buildings. In this paper, the ground settlement surrounding the foundation pit was monitored and predicted according to the historical monitoring data, the construction conditions and the surrounding stratum parameters of a foundation pit project in Qiantan district of Shanghai. Based on PSO-BP neural network, this paper compares the network model based on the time series with that based on the settlement influence factors. It is found that the prediction error of these 2 models is small and the prediction precision of neural network based on the time series is higher, which means that PSO-BP neural network can be used to analyze and predict the ground settlement surrounding the foundation pit. In order to comprehensively consider the time effect and space effect, the historical monitoring data is added as the input layer of prediction model for optimization on the basis of prediction model of settlement influencing factors. The results show that the optimized PSO-BP neural network model has a smaller relative error range and a higher prediction precision, and it has good application prospect in the prediction of ground settlement surrounding the foundation pit.

Abstract:Taking some foundation pit project of huadian group huazhong headquarters R&D base adjacent to the Wuhan Yangtze River tunnel as the research object, the finite element analysis software MIDAS/GTS NX of rock and soil structure was used to simulate the nine construction conditions during the construction of the foundation pit. The deformation of formation, diaphragm wall, and tunnel after the completion of the foundation pit excavation and the tunnel stress before and after foundation pit excavation, were obtained and analyzed. The results show that it was reasonable and feasible to establish the model; the foundation pit excavation and support soil produced the soil displacement outside the pit which caused the maximum 4.17mm horizontal displacement of the tunnel near the foundation pit; the stress value of the tunnel and the change before the excavation of the foundation pit were not significant and within the safe range.

Abstract:A proper layout of precast beam pedestals can effectively reduce the soft ground differential settlement in construction of the precast beam pedestal field on the soft ground section. The finite element software Midas/GTS was adopted to create a three-dimension calculation model for analysis of the influence of the different precast beam pedestal on the soft ground differential settlement. Results show that when the beam pedestals are arranged in the lengthwise direction, the middle one’s total settlement and the maximum differential settlement over each 2m length is greater than the outside ones, with the maximum differential settlement over 2m length larger than that in the widthwise arrangement; thus it is recommended to employ the widthwise arrangement. When the spread foundation is adopted, the overall settlement of the pedestal is significantly reduced from that in the shallow foundation, with the maximum settlement reduced from 11.6mm to 8.5mm, and the differential settlement over each 2m length of the pedestal reduced from 0.41mm to 0.12mm. It is recommended to use the spread foundation in priority.

Abstract:The pile foundation project of Shanghai Oriental Hospital Qingdao Branch (Oriental Hospital of Tongji University) is made up of a large amount of workload with a tight construction period. With presence of backfill soil and silt in overburden, ground conditions are very complicated. Depending on the particular conditions, auger boring, percussive drilling and the rotary drilling were used together with some technical measures such as extended conductors, borehole wall sealing mud, etc. to eliminate borehole contraction and caving. As a result, the project was completed with high quality and full quantity and on schedule, achieving good economic and social benefits.

Abstract:With more demanding requirements of the large scale foundation on the construction progress and ground limitation, construction of the anti-pulling pile before the foundation pit excavation has gradually become the trend. The stress state and ultimate bearing capacity of the pile will change greatly with massive unloading at foundation pit excavation. By combining the numerical simulation of the particle flow with the theoretical analysis of the limit equilibrium, the failure mechanism and ultimate bearing capacity of the anti-pulling pile unloaded at excavation is analyzed. The analysis shows that the damage characteristics of the surrounding soil is an inverted cone shape with the linear failure surface and failure angle. Unloading at excavation has little influence on the failure angle of the surrounding soil, but the influence of the pile length on the failure angle is significant. According to the research results of the mechanism, the theoretical analysis model has been established with the theoretical formula for the bearing capacity and loss ratio of the pile derived. The theoretical formula has been verified by the existing simulation test results.

Abstract:Under the condition of soft soil, the requirements of buildings on settlement deformation and bearing capacity are getting higher and higher, leading to higher requirements on the foundation construction. Based on the high-pressure jet grouting process, the micro-pile construction process with jet grouting was proposed, and tested. The results show that the process greatly improves the bearing capacity of the single-pile pile foundation and provides data support for field applications.

Abstract:the caThe ground subsidence formed at the Huayuan coal mine after the forced closure by the city of Xintai has been basically stable through treatment. In the future without mining and strong drainage, the working area is a basic stable mining-induced sunk area. The treatment design is intended to restore the geological environment, reclaim the land function, guarantee agricultural production, and guarantee the safety of people’s production and life. The design takes into account of the local conditions with proper planning to achieve the coordination and unification of the control effect and the surrounding environment, ensuring the rationality and integrity of the design.

Abstract:Drilling is one of the main technical means for mineral exploration, and the quality of drill holes is of great significance to the resource evaluation and mine design. This paper reviews the history of the development of drilling quality assessment standards by various geological exploration departments, and by comparing the application status of the drilling quality classification standards, it raises some issues below: the existing drilling quality evaluation standards are not unified, different specifications are not compatible, the quality assessment document formats are not unified, and the ecological and environmental protection is lenient. It then presents the index evaluation system and main characteristics of the provincial standard of Heilongjiang——Drilling Quality Requirements For Non-coal Solid Minerals. It is proposed that the competent authorities of the industry should organize the formulation of the drilling quality standard as soon as possible.

Abstract:In view of the differences in the understanding and application of some technical terms used in petroleum drilling engineering and mineral geology drilling engineering, some terms are sorted out and classified in order to facilitate the integration of various technical works, communication and data collection & acceptance. It is hoped that the relevant technical terms can be further standardized and unified in the definition and use, which will be helpful for the future development of unconventional oil and gas geology core drilling.