Abstract:Riserless drilling is usually used in deep sea drilling. For change of the drill bit or the bottom hole assembly , logging or dealing with the incident in the hole, it is necessary to trip out the drilling string and then get it back into the original hole, and this process is called “well reentry”. Because the drilling vessel is separated from the submarine wellhead by water for several kilometers, it is unstable with the drill string swinging due to the waves and ocean currents. It is not easy to reenter the original hole. Through extensive investigations, this article introducesseveral common reentry drilling technologies at home and abroad in detail, compares the advantages and disadvantages of different technologies, optimizes the underwater television reentry drilling technology. The design approach for deepsea drilling well reentry technology is put forward, laying the foundation for development of the prototype and reentry process.

Abstract:In this paper, the reentry drilling systems on board of America’s “Glomar Challenger” drill ship, “JOIDES Resolution” drill ship and Japan’s “Chikyu” drill ship are investigated. This paper introduces the status of reentry drillingtechnology, the composition of the reentry drilling system, the process flow and application of reentrydrilling in ocean drilling. The reentry drilling system and the reentry method adopted on the “Challenger” and the “JOIDES Resolution” drill ship have been verified by a lot of practices, which may provide full reference for design and manufacture of the drill ship for China.

Abstract:Riserless drilling is usually used in ocean drilling where downhole incidents often happens in loose and brokenformations due to instability of the hole wall. The most ideal way to protect the wall is to seal the unstable formation with casing. With the traditional casing RIH method, the procedure is complicated with long operation time, susceptible borehole shrinkage and collapse, difficulty in running the casing to the predetermined position, high construction risk and high cost, etc. This article introduces a casing-while drilling technique by which drilling and casing is combined into one step through a complete set of equipment such as the underreamer, mud motor, and casing running tool. The technique simplifies the operation procedures, saves operation time significantly, and has solved the technical difficulties in casing operation in deep sea riserless drilling in complex formation, such high operationrisk, high cost, etc., providing technical support for deep sea core drilling.

Abstract:Exploration and development of marine solid mineral resources is an important part of marine development and utilization. Some technical measures were summarized and discussed on drilling projects in shallow waters from drilling equipment, technology, safety, etc. First, it is necessary to choose a safe and reliable drilling platform based on the characteristics of the marine environment，in addition to selecting conventional drilling equipment based on geological requirements. Second, the drilling structure design, drilling method and washing fluid should be carried out according to the characteristics and requirements of the sea area. Third, we must adhere to the principle of safety first and compile safety emergency plans. Through the application example of the gold exploration in the northern sea area of San Shandao, the adaptability of marine geological drilling engineering technology has been proven，it provided some experience references for related shallow sea geological drilling projects.

Abstract:The drilling fluid circulation mode has always been concerned in offshore drilling. Under the requirements of the marine environmental protection law and HSE, the reasonable selection of drilling fluid circulation technology must be considered by drilling engineers. This paper introduces the development history and present status of drillingfluid circulation technology in shallow and deep ocean drilling including Oil Casing Circulation, Double CasingCirculation, Conductor Circulation, Riser Circulation, Riserless Mud Recovery System, ReelWell Drilling Method, Hydraulic Reverse Circulation and Gas Reverse Circulation technology. Analysis is made of the equipment structure, construction process and working principle of drilling fluid circulation technology. The market and technicalrequirements of coastal engineering, offshore engineering and exploration and development of deep-water oil, gas and mineral resources on different drilling fluid circulation technologies are put forward with the possibility of application of such technologies in ocean scientific drilling.

Abstract:The floating work platform is greatly affected by weather, wave, tide and other natural factors; thus, construction needs to be done according to the weather window period. It is not suitable for projects with the tight construction period, long operation period and high technical requirements. The jack-up platform designed in this papernot only has the advantages of floating working platforms, refitted barges and other construction platforms, but also has the self-elevation function by which the deck can leave the sea level to avoid the influence of meteorologicaland environmental factors to the greatest extent, effectively extend the construction window period, and improve work efficiency during the construction period; at the same time, the stable marine work platform greatly improves the accuracy of data parameter acquisition.

Abstract:In recent years, geothermal resources have seen continuous development and utilization. With either single well recovery orrecovery by the well set ofa directional well connected with a vertical well, injected surface water and groundwater will exchange in the process of water injection exploitation of geothermal resources, resulting in the pollution of groundwater resources and a large number of environmental hazards brought by tail water since the well bore and the stratum are not completely isolated. It is specially true with the large scale development of geothermal resources in the city. Through the design and implementation of isolated heat exchange technology with connected geothermal wells, this paper analyzes the heat exchange efficiency of connected geothermal wells and the sealing measures between the well bore and the stratum to establish a set of isolated heat exchange and recovery methods, so that heat can be extracted without taking out ground water in the process of geothermal well recovery; thus providingbasic data and technical support for the development of geothermal resources around the city.

Abstract:Compared with conventional coring technology, when drilling in loose, soft, broken and other complex formation, core catching technology can obtain higher core recovery. The core catching tool developed at home and abroad mainly includes double-tube rigid type, double-tube swivel type and wireline core-catching drilling tools. The key points indevelopment of the tools mainly include the design of the core catcher structure and the choice of the loading mode. Development of the core drilling tools shows thatthe core catcher with the triangle slipshas good closing performance and hydraulic loadingcan be accurately controlled to achievethe core breaking force. Wireline core-catching drilling tools have high drilling efficiency, but the development is relatively difficult. In this paper, the structural characteristics and coring operation procedure of the core-catching drilling tools at home and abroad are described in detail. The design advantages and disadvantages are analyzed and the development trend is put forward. All these lay a foundation for the optimum design of core-catchingdrilling tool.

Abstract:Experts and scholars at home and abroad have conducted lots of research on coring in broken formation for many decades, leading to notable resultsin terms of decreasing core entry resistance, increasing core recovery, extending footage per run, increasing ROP, etc. However, less research has been made on solutions to core jamming incidents. To some extent the jam-releasing coring tools represented by JamBuster alleviated the core plugging problem, and extended the footage per round by adding liners, but the problem of core jamming hasn’t been fundamentally solved. This paper summarizes the research state of the special coring tools and technologies for broken formations in the past, analyses their shortcomings, and puts forward some suggestions for improvement.

Abstract:As an efficient and clean energy resource, natural gas hydrate is widely distributed in ocean and permafrost. After exploration and development in recent years, abundant natural gas hydrate resources have been discovered in the South China Sea, and trial production has been carried out successfully. With the further acceleration of gas hydrate exploration and development, more and more researchers have paid attention to fidelity of the core sampler as an important tool for gas hydrate sampling. From the perspective of science popularization, this paper introduces the necessity of fidelity sampling of natural gas hydrate, the development process of foreign countries and the research achievements of China in recent years, so as to achieve the purpose of mutual exchange and mutual promotion, and finally promote the localized application of fidelity sampling technology.

Abstract:There is a great difference between the conditions of laboratory-scale synthesis of aqueous solution polymerizationand those of industrial production at home and abroad, and there is still no simple and feasible proper guidance method. Taking the scale-up synthesis of the water reducer for cementation as an example, and according to the characteristics of the synthesis of the water reducer, this study selects the scale-up criteria with the synthesis process conditions as the main part on the principle of similarity scale-up; hence, has set up a stirring power Np amplificationmodel, and develops the scale up synthesis method suitable for aqueous solution polymerization. The scale-up synthesis method was used in lab to test the AMPS water reducer by 2 to 10 times volume, and the resultingproducts showed that, compared with the small scale test, the differences in the best product conversion rate and the 120°C API water loss were 5% and 10mL respectively. The molecular weight and infrared test results indicated they are the same products. The method has also been successfully used to guide 50L pilot production with stable the product quality, and the physical properties and cementing slurry application test results of the product were consistent with the small test. The results show that the scale-up synthesis method can effectively reduce the influence of the scale-up effect on scale-up synthesis.

Abstract:The concept of green exploration is implemented in the survey work at the Longmen gold polymetallic mine in Laiyuan County, Hebei Province, where special design is carried out for trench exploration, old tunnel cleaning and drilling as per the “Green Exploration Guideline” standard. Humus soil and rubbles dug out during trenching exploration are piled and covered separately. After the project is accepted, humus soil and rubbles are backfilled, compacted and greened; the rubbles removed from the old tunnel is piled a flat place close to the tunnel, and well protected, and then covered with soil and greened; clean water and envionmental protection mud are used as the drilling fluid for drilling projects, with diamond drilling and wireline coring as the drilling process; thus improvingdrilling efficiency, reducing impact on the geological environment with less drilling rig footing, and eliminatingoil spillage during construction. After completion of the project, the landscape is reinstated through grass planting and natural restoration. Green survey implements fully the green development concept that green mountains and clean water are the gold and silver mountain.

Abstract:Based on the formation mechanism of high-pressure rotary jet piles and the current market demand for large diameter pile construction, a spray nozzle has been developed to cope with new processes and methods and eliminate the problems with conventional rotary jet such as small pile diameter, environmental pollution from mud discharge. Analysis of the actual working condition of the nozzle under the ground shows that the newly developed 11-tube nozzle has the characteristics of in-situ pressure detection, mud discharge through special channels, large thru-bore diameter of the slurry pipe, etc., which can realize large pile diameter construction, uniform mud recovery and avoid disturbance to surrounding buildings.

Abstract:In light of the construction process of the RJP method, the hydraulic system of XLT[CD*2]230 high-pressure rotary jet rig is designed to include the following main hydraulic circuits: the power head rotation circuit, which can realize continuous switching between forward and reverse rotation for swing jetting of RJP method; the power head lifting and lowering circuit, which can realize fast/slow lifting and lowering of the power head, and intermittent step-lifting function as well; the drilling rig travel circuit, which can provide for travel stability without deviation; and the auxiliary action circuit to ensure the stability and reliability of auxiliary action. The field construction test showed that the hydraulic system of the drilling rig is properly designed with high reliability and good energy-saving, fully meeting the construction requirements of RJP method.

Abstract:High sulfate-resistant cement grout was used for reinforcing the fractured zone in the flexural core of the dam foundation of Xiangjiaba Hydropower Station. Since the depth of grouting holes was more than 150m, higher requirements were specified for the grout than those used in the conventional process in terms of the stability, groutability, wall reinforcement, separation, initial setting time, strength of stone body, etc. during drilling and grouting construction. Therefore, research has been carried out to compare the high sulfate resistance cement added with the retarded water reducer and the modified the high sulfate resistance cementto deal with the reinforcement of the dam foundation of Xiangjiaba Hydropower Station with grouting treatment, and preliminary results have been achieved . It is found that the stability, groutability, wall reinforcement, separation, initial setting time and stone strength of the modified high sulfate-resistant cement slurry with sodium hexametaphosphate instead of the retarded superplasticizer as the retarder and dispersant are better than those of the high sulfate-resistant cement slurry with the retarded superplasticizer, and its performance is better matched with the process.

Abstract:ThefoundationpitwaterinrushincidentontheundergroundspacefirstＧstageworksinthecentralareaof theJiangbeiNewDistrict,Nanjinghappenedduetolackofcompactionofthebackfillingintheabandonedpileholes inthefoundationpit,whichcausedtheconfinedwaterinthedeeppressurizedaquifertopenetratetheabandonedpile holes,leadingtothewaterinrushincident．Aftertheincident,theholeswerebackfilledwithconcretetocounter waterinrush,andthengroutedtosealoff．Butnoneofthemsucceeded．Throughinvestigationandanalysis,the dewateringprogram wasadopted,wherebythedeepconfined waterlevelwasloweredbelowthe waterinrush positionandgroutwasinjectedtosealoffwithoutthegushingwater．Thisdewateringprogramtook１８daysto successfullyresolvethewaterinrushincident,whichcanprovideusefulexperienceforsimilarprojects

Abstract:This paper studies a field case where post grouting technology failed to greatly improve the bearing capacityof the single pile, and concludes that the main cause for the insufficient bearing capacity of the single pile is the poor control of the grouting process. Strict quality control and installation of the grouting pipe, jet grouting pipe and check valve as well as the grouting process control are the key factors for successful grouting, hence improvementof the bearing capacity. In the above field case, the area with insufficient bearing capacity was treated by supplementary piles. During construction of the supplementary piles, the production of the grouting device was standardized and the control of the grouting process was strengthened. After the supplementary piles reached the agingperiod, the static load test was carried out, and the results showed that the bearing capacity of the supplementarypiles met the design requirements.

Abstract:With the traditional method of repairing the damage of underground sewer pipelines, extravasation is sometimes high. In order to solve this problem, a new method of repairing the damage of sewer pipelines is proposed based on virtual reality technology where the map method is used to position the damage location and damage degree of sewer pipelines, and then the communication simulator transmits the damage signal of sewer pipelines to the computer to output the damage identification of sewer pipelines. Virtual simulation technology is adopted to provide proper adhesive repair in regard to the different damage levels of sewer pipelines. The results show that compared with the traditional repair methods, the sewer pipeline damage adhesive repair material based on virtual reality technologyis more reasonable. After repair, special reagents are used for cleaning to improve the adhesive repair effect of the damage sewer pipeline and reduce extravasation of the adhesive repair of damaged sewer pipelines.