Abstract:Drilling engineering is a heavy physical work. At present majority does it basically by experience. That situation should be changed， the drilling by experience should be changed up to the science. Russian drilling specialists have proposed comprehensive research on the three indexes， i.e. rate of penetration， bit penetration rpm and energy consumption per meter in diamond drilling and developed a software controlling optimization of drilling process. Good results have been obtained by using the software and it is worth for us to learn from.

Abstract:The hot-point drillis often tend to tilt in ice drilling， which results in deviation from the target ice and failure to complete the scheduled drilling mission. To this end， the causes for the inclination of hot-point drills are anaylized and categorized into uneven heating of the ice at the bottom of the thermal head， poor stability of the hot-point drill structure， higher speed of cable unwinding than penetration speed and oversized borehole diameter. The methods of preventing and correcting the inclination in hot-point drilling are summarized， including the thermal method， the gravity method， the buoyancy method， the push method， the centralizer method， the guide rod method and the borehole diameter reduction method， so as to lay a foundation for further research on preventing and correcting the inclination of hot-point drills.

Abstract:With the deepening of drilling depth， breaking hard rock formations became more difficult， and increasing rotational speed has become one of the feasible methods to break hard rock formation rapidly and effectively. The impregnated diamond bit has a good application effect in the hard rock formation， the interaction mechanism between the impregnated bit and rock is relatively perfect at conventional speed， and there is also a corresponding application and research basis at high speed and ultra-high speed. However， the rock fragmentation mechanism at high speed to ultra-high speed is not completely clear. Based on the interface laws for impregnated diamond and rock， a two-dimensional model of single diamond cutting rock is established by using ABAQUS software， and an approximate analysis method is proposed to define and calculate the nominal “tool tip” position， and further derive the force expression of single diamond， in order to explore the rock cutting force and changes of hard rock breaking from conventional speed to high speed and ultra-high speed by single diamond. The result shows that the cutting action of single diamond on rock is mainly concentrated in the middle and upper part of the interface between the cutting tool and the rock. The cutting force of a single diamond at high speed is lower than that under conventional cutting speed， and the main action part is affected by the change of cutting speed. There are plastic fracture and brittle fracture in the interaction between diamond particles and rock， and the two failure modes occur alternately. The proportion of brittle fracture at high speed increases compared with conventional speed， and the fluctuation range of cutting force at high speed is smaller， and the he energy required for rock breaking is much less. An approximate analysis method of rock-breaking response of the impregnated diamond bit is proposed， which equals the diamond particles as a cutting tool with “tip” and “front and rear” through analysis， the force expression of single diamond which is related to factors such as cutting speed and cutting depth is derived， and force is. The research results can provide a basis and reference for further research and application of breaking hard rock formations with increased rotational speed.

Abstract:In the field of small diameter deep hole coring drilling， in addition to the traditional lifting and coring methods， drilling methods such as wireline coring technology and screw motor bottom hole power tools are also widely used. Different bottom hole assembly （BHA） and drill strings together form flexible rods with a large slenderness ratio， which generate complex vibrations during the drilling process， profoundly affecting the safety of drilling engineering. At present， many mature analysis methods have been developed for the theory of pipe string vibration represented by drilling engineering， but research on the torsional vibration characteristics of pipe strings is still insufficient for the vertical hole structure of small diameter deep hole drilling， diamond bit grinding of rock layers， and especially when selecting different BHA and drilling methods. The finite element analysis method is suitable for solving problems with complex boundary conditions， and has good results in analyzing the vibration characteristics of drilling strings. Based on ANSYS software， a variety of typical BHA suitable for small diameter deep hole drilling are selected， and corresponding finite element analysis models are established to solve the relationship between factors such as hole depth， weight on bit， and the torsional vibration characteristics of the pipe string. A solution method for the critical rotational speed that may cause the joint vibration of the pipe string under different hole depths is given. This study can provide some reference for small diameter deep hole coring drilling engineering in terms of BHA selection， rotational speed selection， and string safety evaluation.

Abstract:The special project of comprehensive geophysical research drilling in the Xiaoqinling national integrated exploration area aims to find out the deep geological structure and reservoir characteristics of the hidden ore bodies in the Xiaoqinling area. Due to lack of deep hole and deep geological data， many unknown factors exist in construction. Considering the basic condition of this special drilling project， strata lithology， drilling depth and final hole diameter， practical drilling equipments and wire-line core drilling and LBM drilling fluid system as the main drilling technology should be selected to meet the construction needs. During the drilling process， technical problems such as low core recovery rate in upper strata， water gushing， adhesion stuck， falling block stuck， leakage in the hole， anti-slope in slate layer and difficult in lifting casing were encountered. Relevant feasible solutions were made to provide certain reference for the drilling construction in this mining area or similar strata in the future. At the same time， a mud system for fractured and poorly consolidated strata was summarized and formed， which has achieved good results in maintaining the well wall， effectively preventing major accidents in deep holes， improving drilling efficiency and saving drilling costs.

Abstract:Uranium is an important strategic mineral resource in China. The relevant ministries and commissions of the state， China Geological Survey， China Nuclear Industry Geology Bureau， and many provinces and autonomous regions such as Sichuan， Shandong， Ningxia and Guangxi have clearly increased their investment in uranium geology in the new round of strategic action of prospecting breakthrough. In this paper， combined with the achievements of scientific research projects in production implemented by China Nuclear Industry Geology Bureau in 2021-2022， and the good process practice of some geological exploration units， the influencing factors of geological exploration and drilling production efficiency are systematically analyzed by using the calculation model of meterage per drill working-month， and suggestions on improving quality and increasing efficiency in the whole process of drilling production are put forward， including four specific suggestions， such as improving the pure drilling speed， the utilization rate of table month time， the actual drilling rate and the utilization rate of production table time，focusing on process optimization and introduction of mature tools and instruments. The suggestions and methods for improving drilling efficiency put forward in this paper have been partially verified during the implementation of scientific research projects in production in recent two years， and some achievements have been made in reducing costs， improving quality and increasing efficiency， so it is necessary to further consolidate and explore. Finally， the paper summarizes the general suggestions on production management， equipment renewal， technology citation and talent team construction to ensure the efficiency of uranium geological drilling， which provides a reference for the improvement of geological drilling technology and management.

Abstract:This paper aims at the problems of low drilling efficiency， low core recovery， large disturbance and high accident rate during the coring process of deep-sea hard rock， discusses the fracture mechanism of deep-sea hard rock under the combined conditions of rotary and impact taking the deep-sea hard rock as the research object and using the finite element numerical analysis software. The results show that the rotary rock breaking method can effectively improve the drilling efficiency. In the drilling process，15~25kN WOB and 4~6 mm boss height can be optimized. Under this condition， the ROP is faster， the core quality is higher， and the energy utilization rate is also higher. The closer the working frequency is to the optimal frequency ，the more efficient the drilling will be as long as the strength of the jarring component allows.

Abstract:The implementation of green exploration is a new task and new requirement for marine geological exploration in the new period We actively practice the concept of green development and take the marine ranch project “Marine Ranch Demonstration Area of Weihai City in Shandong Province”， which is the first marine ranch project implemented in the Shandong province， as the pilot project. We first formulated the green exploration management measures and relevant implementation rules， and then rationally arranged construction equipment in the construction process， including improving ship positioning technology， optimizing drilling construction technology， improving geological sampling process， minimizing the use of sea area， reducing environmental pollution and avoiding valve frame damage. The achievements of green exploration have been approved as the second batch of green exploration projects by the Ministry of Natural Resources. The practical experience is expected to provide a working model of marine geological green exploration that can be replicated and popularized for other geological exploration affiliations.

Abstract:With the increasing exploration and development of deep and ultra-deep wells， harsh conditions such as high temperature and high pressure put forward higher requirements for drilling fluid. In view of the difficulty of conventional wellbore strengthening materials to meet the high temperature and high pressure in ultra-deep drilling process， research has been conducted on a graphite material which can expand at 150℃， and its characteristics of plugging and fluid loss reduction in high temperature drilling fluid have also been explored. Expanded graphite is a kind of flexible expansion material with high temperature resistance （500℃）， high expansion performance and self-lubricating property. The initial expansion temperature of the existing expanded graphite is generally higher than 300℃， and cannot expand at the bottomhole temperature. The multi-component oxidation intercalation method was used to prepare the expanded graphite material with initial expansion temperature reduced from 300℃ to 150℃. The expansion mechanism of the multi-component oxidation intercalation is examined， and its plugging and filtration performance in high temperature drilling fluid is further investigated.

Abstract:The Well Wanwangdi-3 （hereinafter referred to as Well WWD-3） is a large-diameter shale gas geological survey directional well which was deployed in Wangjiang Depression of the Lower Yangzi Block， the design depth is 1950m， and the total depth is 1985m. The purpose of drilling is to explore the gas content of the Permian Dalong Formation， Longtan Formation and Gufeng Formation， and verify the regional stratigraphic sequence. This paper introduces the well design and construction process of Well WWD-3， in view of the risks and problems in drilling process， combining the predictive and actual drilling， four technical guarantee measures are put forward including drilling safety， directional drilling， drilling fluid use management and geocloud real-time monitoring of drilling conditions， to ensure the smooth and successful completion of drilling tasks. Finally， combining the actual drilling situation and logging data， the drilling quality， efficiency and core quality were analyzed. The goals of no major accidents during the drilling process， qualified drilling quality， and high-efficient construction progress were achieved. Good economic benefits were obtained， meanwhile， good technical experience for the construction of large-diameter drilling projects in this area is also provided.

Abstract:A sticking incident happened in HDR-1 well at a depth of 3000m in hot dry rock. After various treatments， over 100m long “lost fish” still remained downhole. With the casing-milling method to continue to deal with the fish， it may lead to great difficulty， high risk and long period. After trade-offs of various methods， it is decided to adopt the method of sidetracking to bypass the incident section. Through the comparison of three plans of sidetracking with the deflector inside casing， sidetracking from the open hole cement plug and sidetracking with the open hole deflector， sidetracking from the open hole cement plug was finally adopted. The successful application of sidetracking around the barrier is the first time in hot dry rock drilling in China， which has overcome the technical difficulties of large depth， large diameter，high temperature and high hardness， and applied advanced technology， such as measurement while drilling， complex power drilling technology， high temperature resistant mud， providing new technical support for hot dry rock scientific drilling and deep geothermal resource exploration in China.

Abstract:Hard-plastic mudstone is usually encountered in deep geothermal drilling， which seriously affects the drilling efficiency. Based on the example of deep geothermal drilling project in Xiong^，an New Area，this paper deeply analyzes the reasons of low mechanical drilling rate in hard plastic mudstone， studies and forms the scheme of optimized and improved bit. The practical application proves that the mechanical drilling rate in hard plastic mudstone formation can be effectively improved by using the personalized PDC bit according to the lithology characteristics of the formation combined with the screw drilling tool. The impact resistance of PDC bit can be effectively improved by using special-shaped compacts such as triangular prismatic and triangular and the service life in gravelly formations can thereupon be increased， in addition， the mechanical drilling rate in hard plastic mudstone formation can also be increased. At last， a drill bit application scheme suitable for hard plastic mudstone formation in deep geothermal drilling is made.

Abstract:With the increasing depth of the oil and gas well and the increasing of geothermal drilling， the problem of high temperature drilling fluid is becoming more and more prominent. In the drilling process， it is very necessary to timely cool drilling fluid and make it reach the appropriate temperature for safety drilling. This paper summarizes the cooling ways and characteristics of the current frequently-used high temperature drilling fluid. In regard to the energy-saving characteristics of air cooling and the advantage of high cooling efficiency of the coolant with forced cooling， a high efficient cooling system for high temperature mud is put forward. The air cooler and the tube and shell heat exchanger in the cooling system are designed， checked and simulated， and the reliability of the design is also verified. As a result， the high temperature drilling fluid at 80 ℃ and 1800 L/min can be cooled below 40 ℃ using the cooling system. At the same time， the cooling effect at different drilling fluid temperature， different drilling fluid flow rate and different air temperature conditions is also discussed.

Abstract:With the continuous development of oil and gas exploration and development in the direction of deep wells， ultra-deep wells and other high-temperature and high-pressure wells， the oil and gas industry has put forward higher requirements for the overall gas sealing capability of the liner hanger. The conventional hydraulic liner hanger has a hydraulic cylinder on the body. Pressure transmission holes and rubber seals lead to weak sealing points， which make it difficult to meet the long-term sealing integrity of the wellbore and the high-pressure completion requirements such as fracturing in the later stage. For this reason， foreign companies have successively developed the integral gas-sealed liner hanger technology. Innovations have been made in the design of the seat-hanging drive mechanism. The body of the liner hanger adopts an integrated structure， and there are no sealing weak links such as pressure transmission holes or seals， which greatly improves the overall sealing capability of the system. On the basis of comparing the structural composition of conventional hydraulic liner hangers， this paper introduces the structural principles and technical characteristics of several representative integral air-tight liner hangers abroad， summarizes and analyzes the future development trend of liner hangers， and puts forward Some suggestions for the direction of liner hanger technology research and development in the future are given.

Abstract:In the newly developed geothermal well heating system， it is necessary to obtain more accurate reinjection data through multiple well reinjection experiments， so as to select the best reinjection well. After the geothermal well has been used for some time， the injection well and the production well are reversed. The traditional placement of the reinjection device is more like part of a building project， thus， without proper consideration of drilling operation， geothermal well drilling technology structure， early reinjection test verification， geothermal well maintenance and other factors. There are also some problems with the fixed reinjection device such as large footing area， high cost of investment， complex installation and maintenance. As a result， a mobile geothermal tail water reinjection device is designed and manufactured. This device is featured of simple structure， movement as one piece， rapid installation and transfer as well as multi-level filtration and auxiliary pressurized reinjection.

Abstract:In view of the problems of low success rate and low mechanical strength of long drilling holes along the soft coal bedding， the technical idea of injecting mechanical foamed cement slurry into the soft coal seam by the way of high-pressure rotary spraying while drilling to inforce the fomation is proposed. In the laboratory test， the proportion of soft coal rock and foamed cement slurry was changed to simulate the soft coal rock and foamed cement consolidation body which has different consolidation effects after grouting. In addition， taking compressive strength and gas permeability as the main evaluation indicators， the influence of soft coal content on the performance of the consolidated body was studied. The results show that： （1） Compared with the consolidated body of pure foamed cement slurry， when the content of soft coal rock （hereinafter referred to as “coal content”） was 5%， the gas permeability of the consolidated body decreases slightly， and the gas permeability decreased with the increase of curing time； （2） When the coal content was greater than or equal to 10%， the gas permeability of the consolidated body increased with the increase of coal content； （3） The early compressive strength （cured for 1d） of the consolidated body increases first and then decreases with the increase of coal content. After 7 d of curing time， the strength of the consolidated body decreased with the increase of coal content； （4） After the coal content was between 20%~25% and the consolidation body was cured for 7 d， the compressive strength was 8.65~9.94 MPa， and the gas permeability was 9.08~36.52 mD. The research results can provide useful reference for the wall protection while drilling and gas extraction in soft coal seam.

Abstract:In-situ chemical oxidation remediation can realize the dosing， mixing and reaction of chemicals to contaminated soil and groundwater through shallow mixing， injection well technology， direct push injection， high pressure rotary jet grouting and deep mixing. In view of the hydrogeology， pollution distribution and remediation target of the organic contaminated site， the deep mixing method was used to design and implement the in-situ chemical oxidation remediation， and the detected concentration of each target contaminant in the soil after remediation is significantly lower than the initial concentration in the site investigation and lower than the target for remediation. The engineering practice shows that the deep mixing method is applicable to the in-situ chemical oxidation remediation of organic contaminated sites with deep pollution depth and light pollution degree， and has the advantages of mature process， uniform mixing， less land occupation， small environmental impact， high cost performance and good remediation effect， and has broad application prospects. When the deep mixing method is applied in the field of site remediation， the corrosion of chemicals on equipment and pipelines， the safety protection of operators， and the bearing capacity of the site after remediation should be considered.

Abstract:As the length of horizontal well sections of regional governance drilling projects in coal mining areas increases， the problem of backing pressure during drilling becomes more and more serious， which directly affects the construction efficiency of drilling projects. Taking the Well Zhu 18 of a regional governance project in coal mining area as an example， this paper analyzes that the drop of the backing pressure is led by the friction resistance and rock cuttings bed caused by factors such as drilling trajectory， drilling tool assembly， drilling fluid performance， and displacement. In response to the above factors， corresponding measures have been taken to alleviate the backing pressure problem and the drilling efficiency of horizontal wells is improved.

Abstract:In view of the problem that the trench wall for the diaphragm wall is prone to failure in the process of trench-digging in water rich sand pebble formation， two simulation test schemes are designed with either change of the flow velocity or the particle size ratio by analyzing the relevant research data and on the basis of defining the failure form and mechanism. The numerical simulation results show that the flow velocity has a great influence on the displacement of particles. The faster the flow velocity， the greater the particle displacement， the higher the porosity， and the greater the stress on the wall. The particle size ratio also has a great influence on the displacement of particles， and its effect is similar to that of flow velocity. When there is a lateral limit， the x-direction displacement of the particles will produce a z-direction component after reaching the limit， making the particles move upward. In practical works， it means that when the particle displacement reaches a certain degree， it will inevitably break through the mud film， resulting in the loss of fine particles in the soil， the increase of soil porosity， and finally the collapse of the trench wall.