Abstract:The ocean which occupies 71% of the entire area of the earth contains huge amounts of information such as geology, biology, climate and rich resources. In the national science and technology innovation program of China’s “13th fiveyear plan”, “deep sea, deep earth, deep space and deep blue scientific research” were listed as strategic and forwardlooking major scientific challenges, and the Integrated Ocean Drilling Program (IODP) was selected as one of the five international major scientific programs and projects. However, in deepsea drilling, the operating environments and conditions are more complex than those on land, which is a severe test for drilling vessels, drilling technology, environmental protection measures, and construction organization and management. This paper first summarizes the significance and achievements of ocean scientific drilling, reviews the evolution history and engineering implementation of ocean scientific drilling in the world, and introduces the situation of China’s participation in ocean scientific drilling. Then, this paper discusses the key technical issues in ocean scientific drilling, such as the ocean scientific drilling coring technology, the reentry drilling technology in ultra deep water conditions, the casing while drilling technology, mud circulation in ultra deepwater conditions. A tentative plan for the implementation of the ocean scientific drilling project in China is put forward.

Abstract:The horizontal directional drilling(HDD) technology has been widely used for laying various pipelines, and has the advantages of high construction speed, small damage to the ground, and no interference to the use of the existing pipelines. However, in collapsible formation such as sand pebbles and fine sand, conventional singletube HDD technology often encounters accidents such as guiding deviation and borehole collapse. Based on the existing technology, a dual rod horizontal directional drilling system has been developed, including the doublerotary drilling rig, the inner and outer drill rods, and the dual rod guiding section. The field application proves that the dual rod system has the advantages of high guiding precision and sensitive adjustment direction, and can overcome the problems of poor guiding precision and borehole collapse caused by collapsible formation.

Abstract:In order to solve the problem of low drilling rate in Xujiahe formation of Fenshuiling structure in northeast Sichuan, study has been carried out to improve drilling rates. First, the mineral components and rock mechanics parameters in Xujiahe formation have been obtained through analysis of the engineering geological characteristics. Then, the technical route and measures for speeding up drilling rates in Xujiahe formation have been specifically analyzed and discussed. Applications in F3 well have demonstrated that drilling rates increased in different degrees with use of gas drilling and the combined drilling of screw tool+ hybrid bit and torsional impact tool+ hybrid bit. Meanwhile, the highest average rate of penetration with gas drilling reached 4.78m/h, and increased by 4.49 times compared with conventional drilling.

Abstract:The paper introduces the outline of well Xiangyongdi1 for shale gas geological survey, with emphasis on drilling and incident treatment. This paper summarizes the typical cases of drilling incident treatment in well Xiangyongdi1 well, and analyzes the drilling process and drilling results in respect of the actual drilling strata and logging data. With the diamond wireline core drilling technology, every technical index of well completion entirely meets the requirements of geological design. Well Xiangyongdi1 is the deepest shale gas survey well drilled in Hunan province at present. The incidents and complex problems encountered in the drilling process, such as leakage, burning of bits, drill pipe breakage, etc., have been well solved. With execution of the project, a set of deepwell drilling and inhole incident treament technology system for shale gas geological survey well has been formed.

Abstract:During drilling of shale gas parameter wells in the block of Quanzijie area, there were some problems such as poor formation drillability, strong abrasiveness, slow drilling rate, less footage per drill bit (cone, PDC) and high abandonment rate. Through the analysis and evaluation of the rock drillability of the Quanzijie block, this paper provides the basis for shale gas exploration drilling bit selection and the optimization of the drilling design in this area so as to achieve the purpose of improving drilling efficiency, reducing drilling cost and shortening the construction duration.

Abstract:Based on nitrogen drilling testing in the goaf of Sihe coal mine, the necessity of drilling through the goaf in 3# coal seam to extract gas from 9+15# coal seam was proposed by analyzing the testing data of cores recovered from the coal seam. Based on “three band” theory, it was confirmed that there are drilling leakage zones present in 3# coal seam, which are located at 74.4m above the roof and 22.73m below the floor of the goaf respectively. Using nitrogen fluid to drill these zones can ensure drilling safety and improve the drilling efficiency. In order to meet the requirement of nitrogen drilling, the well structure with three sections and the surface drilling process were optimized. The successful application of the nitrogen drilling process in Sihe mine indicates that this process can be used in the goaf of coal mine, which provides an important guide for the research and application of drilling technology in goaf.

Abstract:It is very important to the cementation design and safety to obtain the actual pressure bearing capacity of formation before cementing. The conventional formation integrity test(FIT) can not meet the cementing requirements due to limits of the formation fracture pressure at the upper casing shoe or the upper casing resistance to internal pressure. An innovative dynamic testing method was proposed in this paper to eliminate this issue and used in the field. This method operates as: increase flowrates at different levels after casing RIH and circulation, record the corresponding pump pressures, drilling fluid properties and amounts of leakage; then use rheology to calculate the formation bearing capacity at critical depths. Study indicates that the dynamic pressure testing method is effective for low pressure leaking wells, and very practical, meeting the FIT requirements for well cementation. The formation pressure testing results provide the basis and guarantee for the cementing design and safety.

Abstract:By introducing and analyzing the characteristics of strata and lithology in the goaf area of the various sections of the Tongting coal mine in Anhui Province, the difficulties are pointed out in the process of drilling and coring. The relevant technical measures such as enlarging the borehole structure, optimizing the drilling tool combination, strengthening the mud performance maintenance were adopted. To deal with serious wellbore shrinkage, the borehole diameter was increased with reduced casing diameter to overcome the difficulties caused by shrinkage when lowering casing. Thickened cement grout was successfully used to deal with breakage of the φ114mm casing, serious stratum fractures and water leakage problems in the goaf. Finally seven boreholes were successfully completed in coal strata, which achieved good economic and social benefits.

Abstract:A broken section of great thickness was encountered in well Xinhedi1 during drilling from 1314.00m to 1419.98m. The formation was highly broken with a large dip angle, and rich in aquifers. Falling stones and water sensitive collapse of the borehole wall were much serious. During the drilling operation, the drilling tools cannot be lowered into the borehole bottom due to the large resistance in the hole. Borehole incidents occurred frequently, and it was difficult to drill through the broken section. In order to deal with the borehole incident and to drill through the broken formation, cement plugging and side tracking were adopted in these zones. Influenced by the complex factors of the hole, especially the dilution of the drilling mud and the erosion resulted by the water systems in the broken belt from 1358.76m to 1396.46m, cement plugging failed early for many times, which wasted a lot of materials and the drilling time. A set of specific and practical measures were developed through field testing, which solved the technical difficulties of the cement plugging in the field, and improved the success rate of the wall protection with cement plugging and side tracking, providing reference for similar construction in the future.

Abstract:In the secondstage of Fuling gas field development, the geological structure is more complex than that in the firststage, with the deep buried depth of the target layer and the varying dip angle over the horizontal section. These objective factors make drilling difficult and the drilling duration is generally extended. Jiaoye 91 platform is located in the southwest edge of Jiangdong Block, where the geological conditions are complex, and drilling is difficult. In this paper, the complex situation encountered in the drilling process of the first well JY912HF in the platform is analyzed, and the main reasons for the long drilling duration are analyzed. During the construction of the following two wells, technical measures, such as improving leak plugging measures, optimizing bits and PDM, optimizing the borehole trajectory, matching downhole tools, improving drilling fluid performances and using rotary steering tools, were adopted. Fine construction has been carried out to solve the problems of the first well, and good results have been achieved. The bit run and ROP have been greatly improved, and the drilling duration has been greatly shortened, providing the construction experience for drilling in the area.

Abstract:Scaling on the inner wall of the wireline drilling rod can cause drilling rod corrosion, blockage in running the fishing tools and the inner tube assembly, borehole wall instability, etc. The common types of mud scales occurs in the eddy region, or due to extension, leakage and so on. Based on analyzing the reasons and influence factors of mud scaling, the preventive measures are made in this paper, includi drilling fluid optimization, drilling parameters optimization, borehole structure and bottom hole assembly optimization and so on. At the same time, the mud scale cleaning device has been developed. The mud scraper, lowered into the hole through the winch with power supplying and the armored cable, can actively clean the mud scale or adsorbates on the inner wall of the drill rod to keep it clean, so as to achieve the goal of high efficiency and safety drilling.

Abstract:In order to solve the drawbacks of the conventional liner hanger, such as the small flow area, poor sealing performance, the expandable liner hanger is investigated in this paper, with focus on the working and structural principle, as well as the key technology which covers slurry displacement, cementation, expansion suspension and the junk sub. A series of technical problems with expandable tube suspension have been solved. The finite element analysis for the force of the expandable tube is carried out, and the results are compared with those from the laboratory tests and they are basically in agreement. The field experiments proved that the expandable liner hanger can provide enough suspension force, satisfying the requirement of the suspension.

Abstract:A structure for changing the propagation ways of the impact stress wave in the jet type fluid hammer is designed, and analysis shows that the attenuation degree of the stress wave changes with different propagation ways. The simulation on the hammer returnstroke is analyzed based on LSDYNA. The stress change of the fluid element is studied when the hammer impact is propagated in two different ways in the return stroke of the jet type fluid hammer. The results show that the power external transmission mechanism can greatly reduce the impact stress acting on the fluidic element by avoiding the rigid collision on the upper part of the cylinder. Moreover, the geometric parameters of the external transmission mechanism also have some influence on the stress attenuation.

Abstract:Taking a project in Dongying as an example, based on the test results of pile test in the Yellow River flood alluvial formation, the relation curve between the measured average value of the ultimate bearing capacity of single pile and the height of the pile bottom (which can be converted into pile length) under the condition of the same pile top elevation (-5.7m) is set up. The difference between the test pile test and the measured value of the ultimate bearing capacity of the single pile is quite different from the predicted value. The reasons and the optimal design method of pile foundation bearing capacity are introduced. According to the test results of the pile foundation, the measured value of the ultimate bearing capacity of the single pile under the same length and diameter of the pile is about 10% compared with the predicted bearing capacity, which can achieve the potential of excavating the geological conditions, reducing the number of piles and saving the cost of the project. Relevant test methods and methods of optimizing pile bearing capacity design can provide reference for engineering design under similar geological conditions and the establishment of regional pile bearing capacity database.

Abstract:In petroleum and geological exploration drilling, PDC bits have been widely used with good technical and economical results. But in deep drilling, particularly in complicated formations, such as softhard alternate formation, fractured formation, abrasive formation, the penetration rate of PDC bits is slow and the bit life is reduced; thus hindering its further promotion and use. How to increase the performance of the bit, i.e. its strength (hardness) and abrasiveness to resolve above mentioned problems is a very important issue. The integrative treatment of PDC bit with cryogenic nitrogen and magnetization is a simple and effective method to increase the performance of the bit. Results of theoretic study and field practices done by Russian specialists show that the bit performance can be increased effectively with the above treatment method.

Abstract:The TBM excavation tunnel, due to the limitation of the boring head and the cutter, the tunnels currently excavated are of the same diameter. In order to ensure the strength of the structure in the later lining construction, it is necessary to adopt different lining thicknesses to different surrounding rock types. Our research indicates that take variable diameter full circle needle beam formwork trolley has obvious advantages in this aspect of lining. Based on the Songhua River water supply project in central Jilin cities, this paper discusses the application of variable diameter full circle needle beam formwork trolley in the TBM construction tunnel lining.