Abstract:The 1998 Mallik 2L-38 Hydrate Research Well Program in Canada’s Mackenzie Delta, permafrost area, led by the GSC and the Japan JNOC, was successful, but the goal of producing from NGH was not accomplished for the warming weather and mechanic failure. GSC and JNOC, as well as other 8 partners returned to Mallik in 2002. Three wells-the 3L-38 and 4L-38 observation wells, and the 5L-38 production well were drilled. Gas hydrate core was gained from the 5L-38 well at 90% core recovery and geophysical studies were conducted. Two short-duration production tests were conducted—a depressurization test with MDT tool and a thermal injection test. One encouraging result was the 470m3 of gas production by a thermal injection technique employing hot fluid circulation. Then, for the 2007—2008 Mallik production test program, the 2L-38 well, drilled in 1998, was modified to establish a production test well by reaming, deepening, casing, and cementing. An ESP was set below the perforation zone to depressurize the formation by dropping the water level in 2007. During 125h of the test, at least 830 m3 of gas flow was obtained. The test results verified the effectiveness of the depressurization method even for such a short duration. The 2008 testing program at Mallik confirmed that continuous gas flow ranging from 2000 to 4000 m3/day was maintained throughout the course of the 68 day (139 hour) test. Cumulative gas production volume was approximately 13000m3, which data confirms that the depressurization method is the correct approach for gas hydrate production. The 2008 Mallik gas hydrate production program was a landmark in hydrates R&D in the world.

Abstract:In 2016, trial-producing horizontally butted well of gas hydrate was carried out in permafrost area, Qilian Mountain. Reasonable drilling parameters and mud formula have been made according to the different well sections. Precise docking has been realized under small curvature radius by using the MWD technology and SmartMag target-hitting guide system. Drilling technology of horizontally butted well has been successfully applied to gas hydrate trial-producing and good results has been achieved. The drilling construction of horizontally butted well for gas hydrate trial-producing is different from that for dissolvable minerals, which requires a higher accuracy on connection and is also more difficult to be put into effect. This paper mainly introduces the drilling construction technology of horizontally butted well for gas hydrate trial-producing.

Abstract:D7H well of Dongfang 13-1 of gas field in Western South China sea is the first offshore high temperature and high pressure slim horizontal well in China, its reservoir physical property is mainly of medium to low permeability, the drainage passage is easy to be blocked due to the use of the drilling fluid with high solid content, which causes reservoir damage; and being restricted by offshore completion method and up to 10 days retention time of drilling fluid in borehole, the extent of reservoir damage will inevitably be exacerbate. In view of this, a lot of indoor optimization evaluations were carried out, oil-based drilling fluid suitable for reservoir protection in offshore high temperature and high pressure slim horizontal well drilling and completion has been optimized. The pollution mechanism of high density drilling fluid is analyzed, the relationship among flow back pressure difference, flow back time and core permeability recovery results are studied and the measures to improve reservoir protection effect by flow back pressure difference increasing and flow back time prolonging are put forward. The experiment results show that after the core is contaminated by high density drilling fluid under high temperature, the initial permeability recovery value is about 85%, when the polluting time is up to 15 days, the permeability recovery value plunged to 30%, which shows that the longer the residence time of the drilling fluid in the reservoir, the more serious the pollution is; in the same displacement condition; along with the time prolonging, the permeability recovery value increases and becomes stable; the pressure difference increasing in flowback is conducive to increasing permeability recovery value, when flowback pressure difference reaches 12MPa, the permeability recovery value of drilling fluid system may be increased to more than 80%. The field application results show that the skin factor is zero in D7H well testing, production is 6.0×105m3/d, exceding proraton produciton nearly 3 times, good reservoir protection effects is received, which provides important reference for subsequent large-scale development of offshore high temperature and high pressure horizontal well.

Abstract:The designed depth is 1600 meters for the shale gas survey well Yingdi-1. During the construction process, several high stress water gushing fractured zones were encountered, the largest watering quantity was 135m3/h and wellhead pressure was up to 2.5MPa; there was hydrogen sulfide dissolved in formation water, the highest content of hydrogen sulfide gas escaped from the gushing water was up to 100ppm; the water temperature is high up to 50℃ in gushing spot at 1300 meters depth, these difficulties brought safety risk to the construction. In view of the above, this paper introduces water plugging technology by cement slurry grouting, balanced drilling technology with high density drilling fluids and multistage casing technology for well cementing used in drilling process and summarizes the characteristics of each technology, which can be reference for the shale gas investigation well drilling construction in Southwestern Sichuan.

Abstract:Sticking is one of the most frequent, time-consuming and the biggest loss accident in the geological hole drilling. In the sticking accident handling process, the location determination of sticking points is the key. At present, the determining methods of the sticking points of the drilling string in the geological drilling holes mainly are magnetic injection, direct use of magnetic locator, point measuring instrument and the formula calculation. This paper introduces the working principle and operation steps of the sticking point measuring method in detail, and compares and analyzes three measuring methods of the card points. This paper introduces the working principles and the operation steps of the sticking points measuring methods and makes analysis and comparison of these 3 methods. At the same time, the calculation formulas and operation steps of parameters determining for the single and compound pipe columns are given. It is found that the measuring instrument has high accuracy but with limitation as well as time-consuming and costly; the formula calculation is simple and easy but with low accuracy. Therefore, the measuring instrument and formula calculation should be combined in the field to determine the location of sticking point more quickly and accurately in order to reduce economic loss by effective measures.

Abstract:Rotary steering tools are widely used in Bohai oilfield. Because of the instable built-up rate, screw motor drilling tools are generally adopted at the shallow formation drilling, and then rotary steering drilling tools are used instead. When with the screw motor drilling tools, slide steering efficiency is low; on the other hand, it will take 12～15h to trip out for the drilling tools replacement. If the rotary steering drilling tools are used from the very beginning without tripping out for drilling tools replacement, the operation efficiency will be greatly improved. By the technical measures of directional well trajectory optimization, selecting rotary steering tools by comparison and drilling fluid performance optimization, rotary steering drilling technology has been successfully applied in the shallow unconsolidated formation of Bohai.

Abstract:Strata breaking, fracture development, alteration diversity, water gushing and hard intact rock co-exist in Chaijiagou molybdenum deposit, and most of the geological design requirements are inclined holes. The technical difficulties were countered in drilling construction, such as water leakage, collapse and block falling, slow footage and serious inclined drilling. This paper summarizes the experience of drilling construction in borehole structure, flushing fluid solution configuration, wall protection and plugging, hard rock drilling, the use of weighted mud in water gushing formation and the precautions of inclined hole construction with vertical shaft drilling rig.

Abstract:In geological survey well engineering for CBM resources investigation and evaluation project in Miaoergou area of Changji of Xinjiang, the designed well depth was 2500m, and full borehole coring was required. There are problems of difficult coring, leakage, hole shrinkage and winter construction. By adopting special coring tools, enlarging bit outer diameter and annular clearance, heating with oil heater and some effective measures, the difficulties in drilling technology and logistics supply are effectively solved to provide data for CBM resources investigation and evaluation in this area.

Abstract:Well Chengtan-1 is the first ultra-deep well over 7000m in Tadong block of Daqing oilfield. Through analyzing the data of the adjacent wells and optimizing the wellbore structure, BHA and drilling fluid system, a bit series suitable for Gucheng block was established. Using China-made hydraulic rotary tools, the difficult drilling speed improvement in “black quilt” formation of Tadong, where a φ241.3mm hole was located, was solved and the drilling cycle was shortened by higher ROP.

Abstract:Well ADM6-4H was completed by MWD and screw drilling tool combining construction in AHDEB oilfield, which is a 6-inch slim hole with the length of 1500m in horizontal section and the maximum horizontal displacement of 1915.17m, and is also a horizontal well with the maximum horizontal displacement in AHDEB oilfield at present. Polysulphonate oil-mixing drilling fluid system was used in the fourth spudding horizontal section drilling, for its outstanding application effects of sand carrying, borehole wall stability and lubricating, the drilling speed was fast with small drilling torque and stable drilling fluid properties; there were no borehole instability, lost circulation, sticking and back pressure.

Abstract:Double-bend screw refers to the drilling tools combination form of bending joint and bend housing screw. The use of double-bend screw for hole straightening can get larger built-up rate to solve the difficult straightening while using the single-bend screw in some specific conditions. Selecting proper angle of bend joint and shortening deflecting distance of double-bend screw are important factors to control dogleg angle, which can ensure later work of smooth reaming and casing. Take the straightening case in a large diameter drilling, the difficulties encountered in straightening with single-bend screw are listed, by the analysis on the deflecting effect of double-bend screw, a set of straightening technology with double-bend screw is put forward and successful borehole straightening is finally realized.

Abstract:In order to improve deep drilling speed, protect and detect reservoir of Daqing, based on Mohr-Coulomb criterion and by the introduction of linear correction coefficient, the model of formation caving prediction for deep well was established. The feasibility analysis is made on the natural gas drilling in Xushen gas field about geological conditions, gas well conditions, safety, economy and technical conditions. The second section of Quantou formation to central Yingcheng formation（about 2700~4000m）of Xudong, Xuzhong, Fengle and Shengping blocks are determined by optimization as natural gas drilling sections. The results show that it is feasible to improve deep drilling speed by natural gas drilling, which is also beneficial to deep natural gas exploration in Daqing.

Abstract:There are many defects in the traditional reinforced deep mixed piles construction, such as low efficiency in steel pipe inserting operation, high cost and difficult control on elevation height and verticality. A set of new and simple method of deep mixing pile inserting steel pipes was designed for a foundation pit support project in Nanjing, the devices of this system are simple to manufacture and install, the construction difficulty and cost are reduced and the working efficiency is improved.

Abstract:PHC pipe pile has been widely used in China because of its advantages of high vertical compressive bearing capacity and short construction period. Combined with the engineering case of the second stage project of an oil depot in oil sharf of Rizhao port, PHC pipe pile was first used, this paper elaborated the construction in the PHC pipe pile selection, anticorrosion measures, points of hammering construction technology and control measures in strong corrosion condition, which can be reference for the similar engineering.

Abstract:For the construction with reverse construction method, the accurate positioning and verticality control of steel lattice column are difficult in the foundation construction. In Laopupian commercial and residential project of Wuhan, the guide frame and positioning frame of steel lattice column are designed and manufactured, the verticality and positioning adjustment are smoothly completed. By the analysis on the detected data of the excavation with reverse construction method, it is proved that both the verticality and positioning can meet the design requirements with the newly designed guide frame and positioning frame, the construction cost is effectively reduced.

Abstract:Oil casing is usually under the complicated internal and external stress environment. The study and analysis on the influence of these factors on casing collapse resistance ability are very important, which can provide theoretical basis for casing strength design. Based on the stress characteristics of casing under external non-uniform load and internal pressure and the theory of material mechanics, a calculation model of hoop stress of ideal casing at unit length is established, the distribution regularity of hoop stress of internal and external casing surfaces is revealed. The calculation shows that the yield failure point is at the internal surface in circumferential direction of 90 angle with maximum horizontal crustal stress. A new formula of external collapse resistance ability under non-uniform external collapse load and internal pressure during casing buckling is derived from the failure point by Von Mises yield criterion. Calculation examples show that non-uniformity coefficient of external load has the greatest impact on external collapse resistance ability among all the influence factors on collapse resistance ability of casing. The larger the non-uniformity coefficient of external load is, the faster the collapse resistance ability of casing declines; under less external load non-uniformity, the external load bearing capacity of casing can be improved by increasing the internal pressure and decreasing casing diameter-thickness ratio.

Abstract:Geochemical sampling methods are important for geochemical exploration in the forest vegetation coverage area. Due to the widespread influence of the vegetative cover, it is difficult to achieve the ideal effect in Daxing’anling area. This paper introduces the research work of geochemical samples collection using portable shallow sampling tools in the Daxing’anling area, it is concluded that shallow drilling for geochemical samples collection can be widely used in geophysical and geochemical anomaly verification, mineralized body tracking, digital mapping and other geological work. At the same time, this method plays positive and important role in the ecological civilization development.

Abstract:YZX108 hydraulic hammer is successfully developed by theoretical calculation, 3D simulation and combination of experimental and field tests, the diameter specifications of YZX hydraulic hammer is perfected. Through the indoor debugging, the working parameters and the characteristics of the hydraulic hammer are determined. The production tests show that this hydraulic hammer has advantages of simple structure, stable working condition, good adaptability and large impact energy; with this hydraulic hammer, good effects can be achieved in hard rock formations such as cherty limestone, where it is hard for diamond rotary drilling.

Abstract:Reasonable axial clearance setting of turbodrill stator and rotor can ensure free rotation of rotation system to avoid the damage caused by the stator and rotor collision. The axial clearance is very important for tool’s service life, but it is difficult to determine a optimal value, which only can be in a range because of the interference of parts machining errors, expression deformation and some other factors. In order to analyze the influence of axial clearance on the performance of φ89mm turbodrill, the theoretical analysis is carried out on efficiency and performance parameters calculation process in this paper combining with numerical simulation. Numerical simulation is made on single-stage φ89mm turbine with different axial clearance by using computational fluid dynamics(CFD) software. The results show that the axial clearance has only slight influence on φ89mm turbodrill in a reasonable range and can be negligible.