Abstract:This paper presents a comprehensive borehole solution mining methodology in light of the geology and production at the Turkish Kazan trona mine in order to reduce mining costs, make full use of mineral resources, and solve some problems with the existing mining process. A borehole solution mining process has been designed by determining the various parameters and principle of the well layout. The process combines a variety of mining forms and well group types, such as horizontal well, branch wells, fractured wells, close-loop circulation single well and so on.

Abstract:In underground drilling for drainage in coal mines, the deviation between the drilled borehole trajectory and the designed borehole trajectory is large due to absence of inclination measurement technology to control the drilling trajectory; thus it can not meet the design requirements of gas drainage in coal mines. This paper expounds the technology of three-dimensional trajectory measurement while drilling, aiming at precisely controlling the trajectory of gas drilling in bottom drainage roadways through the investigation of 3-D trajectory measurement technology while drilling, and achieving fast tunneling, and safe and efficient mining in gas outburst coal seams. The technology of 3-Dimensional trajectory measurement while drilling is to accurately measure the inclination of drilling holes and the trajectory of drilling holes, and present them with the 3-D trajectory mapping method. Through a large number of data acquisition and field verification, it has been proved that this method has become an important link in the process of coal seam safety and production, avoiding the blindness in borehole design and drilling, and improving borehole drainage coverage and drilling rates.

Abstract:Well CSDP-02 is the second well of the eastern sea scientific drilling project of China. The well was completed in 504 days with the five-section structure, at completion diameter of 98mm, and depth of 2843.18m, setting the world depth record in marine scientific full borehole core drilling. This paper introduces the drilling process of the well. The drilling time, drilling efficiency, and footage per run of the well are systematically summarized and analyzed. Based on the analysis, the factors affecting the deep offshore drilling efficiency, such as sea conditions and logistical support, are briefly expounded, which provides reference for improving the deep offshore drilling efficiency.

Abstract:In the context of geothermal drilling equipment and well structures in Guizhou Province, the application of air-lift reverse circulation drilling technology in geothermal well drilling is summarized, including the direct mud circulation and air-lift reverse circulation principles, drilling equipment, BHA, immersion ratio, drilling parameters and so on. The field results of air-lift reverse circulation drilling technology in geothermal well drilling proved that it can improve the drilling efficiency in dissolved fractured formation, reduce incidents down the holes. At the same time, this technology provides good borehole cleaning in thermal reservoirs.

Abstract:The Paleogene strata in Hebei Plain mainly consist of Dongying Group, Shahejie Group and Kongdian Group, which are lithologically marl, mudstone, calcareous mudstone, gypsum mudstone and sandstone. There are many physical and mechanical factors that affect the core drilling rate. The study shows that the rock density and compressive strength increase with the formation depth. The rock density of the first to the third member of Dongying Group and Shahejie Group is significantly lower than that of the fourth member of Shahejie Group and Kongdian Group. The higher content of clay minerals in the mudstone section of the Paleogene strata results in greater elasticity and plasticity of the rock, which has a significant influence on the drilling rate. In this paper, the drillability of the Paleogene strata and the reasonable matching bit types are presented for core drilling.

Abstract:In drilling at Beigou Molybdenum Polymetallic Mine, Wangjiazhuang, Chengde County, Hebei Province, the main rock encountered was chert strip dolomite and quartzite with strong drillability, and they were hard, brittle, broken and seriously slippery, leading to very low drilling efficiency. In order to improve drilling efficiency, the lithology was assayed through sampling the rock with the drill bit custom-made for the formation. A variety of methods were adopted to force exposure of the cutting elements, and different drilling parameters and drilling fluid systems were selected for the lithology over different sections of the borehole. This paper summarizes the drilling parameters suitable for the formation in this mining area, together with the drilling fluids of different performance for wall protection and leakage plugging, and higher drilling efficiency.

Abstract:During the second stage development of Fuling Shale Gas, in order to detect formation changes in time, near-bit instruments were used in the first well planned on the drilling platform, so as to adjust the well trajectory in time and improve the intersection rate of high-quality shale. Placement of the near-bit instrument and the bit in front of the power tool will increase the load on the drive shaft of the power tool and easily lead to fatigue damage of the drive shaft. When Well Jiaoye XX-HF was drilled to 3971.42m, no signal was received from the near-bit instrument. After pulling out the drilling string, it was found that the driving shaft of the power drill tool broke off and the near-bit instrument and the bit were lost in the wellbore. The fish in this well was short and in the horizontal section; thus it was difficult to find the head of the fish. It was also difficult to determine whether the fishing tool touched the top of the fish by resistance due to the high friction. Through careful analysis of the fish, a feasible fishing plan was worked out, and the fishing box tap was processed on the spot. Finally, the fish was lifted out safely. The ideas and technical measures adopted in this well can be used for reference in dealing with similar accidents in the future.

Abstract:At present PDC drill bits are widely used for deep hole drilling in hard rock, where the phenomenon of stick-slip vibration often happens in the drilling process, causing low drilling efficiency and short bit life-span. In order to solve this problem, a new torsional impactor has been developed, which can not only mitigate stick-slip vibration of the PDC bit by torsional impact, but also cater to high temperature deep hole drilling environment. The turbine set is designed as the power supply for making full use of mud energy with the universal joint and the reducer used for torque transmission; then torsional impact is achieved by rotating of the impact components. According to this design concept, structural design, prototype trial-manufacture, test platform construction and performance test of the torsional impactor have been carried out. The test results show that the design of the torsion impactor is feasible. It provides impact frequency of 4 to 5Hz with the calculated torque per impact at 651.45 to 814.28N ·m, achieving the initial design goals.

Abstract:The structural principle and main performance parameters of the rotary-percussive PDM are elaborated in this paper. With the combination of impact rock crushing with shear rock cutting of the PDC bit, the tool can provide both the advantages of percussion drilling and PDM drilling, and improve the drill bit’s working performance, resulting in higher ROP. It can also reduce drag forces; thus increasing directional drilling efficiency. The tool impact force has a positive correlation with the weight on bit while the impact frequency is directly proportional to the motor rpm. Tests of the φ178mm drilling motors have been carried out in drilling vertical and directional wells in Linpan Oilfield respectively. ROP in compound drilling was improved by 22.1%～41.8% compared with that of the adjacent well, while the slide drilling ROP was increased by 51.1%, which is of positive significance for speeding up the oilfield exploration and development and reducing drilling cost consequently.

Abstract:Expandable profile liner （EPL）technology is mainly used to solve technical problems such as frequent accidents in complex deep boreholes and limitation of casing tiers. Hydraulic Expansion of EPL is a key link in the application. In order to study the mechanical properties of expandable profile liners under hydraulic expansion, and improve the treatment of downhole accidents, the finite element numerical simulation and indoor laboratory tests were combined to study the hydraulic expansion process of expandable profile liners (EPL). Through multiple laboratory tests on hydraulic expansion of EPL, and comparison of the results with those of the finite element theoretical analysis, it was found that both methods obtained basically consistent results. The elastic deformation pressure of EPL is 0 to 2.5 MPa, and the displacement rate of the key points on the cross-section is larger when the pressure of the liner string is 3 to 9 MPa; the hydraulic expansion pressure of EPL is 14 MPa; and the maximum and minimum diameter for the cross-section dimension of EPL after expansion Xmax are 136.98 mm and 104.58 mm; which meet the requirement of the cross-section size for mechanical expansion of EPL. It provides important theoretical basis and technical support for field experiment and industrial application of EPL.

Abstract:In order to increase the intelligent level of trenchless equipment in our country, and upgrade the hydraulic system of drilling rig from the transmission function to the intelligent control function to achieve proper drilling, an intelligent multi-functional directional drilling system has been developed. The system also protects the motor from the “overspeed”, “overpressure” and “ air-vacuum” phenomena that are prone to occur during drilling, relieves the pressure impact of the system through the compensation of the pump displacement, and intelligently matches the engine power according to the load to prevent the engine from stalling.

Abstract:In recent years, cement-soil has been widely used in soil reinforcement projects, and its strength is closely related to the reinforcement effect. In order to study the effect of the adding amount of bentonite and fly ash on the performance of cement-soil, the basic mechanical properties of 25 groups of cement-soil with different adding amount of bentonite and fly ash were tested. Through the compressive strength test, it was found that when the blending amount of fly ash and bentonite was 40% and 11% respectively, the 28d compressive strength of cement soil was the largest at 7.30MPa; when the blending amount of fly ash and bentonite was 20% and 7%, the 90d compressive strength of cement-soil was the highest at 7.19MPa. Through the indoor direct shear test, it was found that when the fly ash and bentonite content was 20% and 11% respectively, the 28d cement-soil shear strength parameter, e.g. cohesion c, was the largest at 1144.8kPa; when fly ash and bentonite was added with the amount of 30% and 5% respectively, the cohesive force c of the 90d cement soil shear strength parameter was the largest at 1753.71kPa. The research results can provide reference for the on-site preparation of cement-soil with fly ash and bentonite in Wuhan area.

Abstract:In the construction of super deep and large diameter bored piles for bridges, the high torque full-hydraulic circulating drilling rigs are usually used with roller bits to drill holes and air lifting reverse circulation to clean the holes. However, for deep and thick bouldery strata, it needs to break the cobbles when drilling, and there are some disadvantages such as low drilling efficiency, high construction cost, drill pipe blockage, slurry leaking, borehole collapse. In view of the above-mentioned shortcomings, the rotary drilling rig was chosen to drill holes with the wall protected by bentonite mud. Reliable plugging measures were taken for the leakage of the bouldery layer and the hole was cleared twice by air lifting reverse circulation to ensure the thickness of the sediment at the bottom of the hole. The construction efficiency has been greatly improved; and the construction period has been greatly shortened which saved construction costs, and ensured the quality of the pile foundation.

Abstract:Russian drilling specialists have proposed such an idea that in normal diamond drilling the quantity of produced cuttings should be correspond to the quantity of cuttings discharged by the drilling fluid, otherwise the cuttings will fill the bottom of the hole, forming “cuttings cushion” and obstructing rock fragmentation. Therefore, in designing the drill bit and defining the drilling parameters, equality between the volume of produced cutting and that between the face of the bottom hole and drill bit matrix (i.e. the filled volume of the hole bottom) should be guaranteed. On this basis, the calculation formula for defining the penetration rate (footage per revolution) is presented. The formula shows the function of the penetration rate vs diamond exposure at drill bit face and degree of discharged cuttings. The concepts of normal and anomalous diamond exposure have been given. Laboratory and field production experiments have been performed on the diamond drill bits with normal and anomalous diamond exposure with positive results.

Abstract:Based on the rock damage theory, the damage deterioration model of rock under the freeze-thaw cycle is derived. The freeze-thaw cycle test method is used to test the physico-mechanical characteristics of the Houwaizi Tunnel limestone rock sample, and analysis is made of its damage deterioration law. The results show that the rock mass and the longitudinal wave velocity of increase first and then decreases with freezing-thawing cycle, the uniaxial compressive strength decreases continuously with freezing-thawing cycle, and the elastic modulus and peak strain increase gradually with freezing-thawing cycle. Through analysis, the relationship between the total damage variable and strain of limestone under the action of freezing-thawing cycle is obtained. The combined action of freezing-thawing and load will aggravate the total damage, the coupling effect will weaken the total damage, and the limestone strain values tend to agree that the number of freeze-thaw cycles is not the main factor affecting the strength limit.