| The 21st century is turbulent, from the war in Afghanistan and the war in Iraq to the Iranian nuclear crisis, the Syrian crisis and America and Iran hold military exercises in the strait of hormuz, from Crimea problem, Ukraine crisis and America and Russia hold military exercises in the Mediterranean Sea to Saudi Arabia lowers oil prices, the ruble devaluation and Russian financial crisis, and Today, our Chinese government speeds up to the implementation strategy of high-speed railway connecting the Middle East and Europe, actively promotes to build a new "silk road", builds the oil pipelines between northwestern Xinjiang and Kazakhstan, between the northeast and Russia, between southwest and Myanmar, which all show the oil energy strategic significance.With the exploration and development develop to the deep well and ultra deep well, in order to improve the economic benefits of deep well drilling, choosing appropriate downhole drill motors to improve drilling efficiency becomes a research hotspot. Downhole drill motors include turbodrill, screw drill and electric drill, among them the turbodrill has the advantages such as fast drill, not controlled by temperature, good adaptability to environment, easy to adjust at the scene, high hole quality, good directionality, high drilling stability, MWD, can protect the bit and downhole tools series. High speed turbine with impregnated diamond bit can effectively improve the drilling efficiency in deep strata, however, the research of the impregnated diamond bit based on high speed turbine operating conditions in our country is little at present, and the research of impregnated diamond bit blade material under the condition is only a handful, and the research depth is not enough. Due to high speed turbine drilling have the characteristics of high speed/high line speed, low WOB/low specific WOB and the large amount of pump, the performance is put forward new requirements to the impregnated diamond bit blade material.Based on high speed turbine drilling process conditions, the impregnated diamond bit blade material is studied in the paper. First of all, the paper has carried on the three rounds of indoor experiment, we optimized the best impregnated diamond bit blade material formula and the sintering process. Then, the modification research of the impregnated diamond bit blade materials is conducted on, including the research of the pore-forming agent when drilling slipping formation under low WOB/low specific WOB and the research of the solid lubricant when producing high temperature frictional heat under high speed/high line speed. Finally, the field application research is carried out.There are 10,12 and 12 bits designed separately in the three rounds of indoor test, the effect of the blade material, diamond parameter and the sintering process on the performance of the bit is studied through drilling tests. There are 8(2 have no penetration),9(3 have no penetration) & 12(all bits are drilled) bits and 64,120 & 456 trip drilled separately in the three rounds of indoor test, and the total penetration are separately 8.12m,18.256m and 65.725m, and the average rate of penetration are separately 0.883m/h,1.451m/h and 2.31m/h. By comparing the three rounds of test result, the bit drilling performance is increased in a multiple and the bits performance is the best in the third round of test. By the blade material, most bits are WC based in the first round of test, and its content is as high as 40%, the hardness is large, the soft Cu-Sn based, Cu based and Co based bits are used in the second and the third round of test, the diamond is quickly wear in high speed/high line speed, the soft matrix is advantageous for the bit’s self-sharpening, and can raise the bit rate of penetration. And the Co based matrix has good toughness, impact resistance and high temperature adaptability, can improve the strength of diamond-setting, reduce loss, improve bit performance. By the parameters of diamond, using a single large size SPC110 diamond bit performance is poorer. The diamond in blade lip surface per unit area is less because of the large size of diamond particles, and difficult to achieve uniform distribution of the diamond, easy to pull slot. The small and medium size mix diamond formula, which is beneficial to uniform distribution of the diamond, and we should improve appropriatly the diamond concentration, which can increase the risk of diamond carved into the rock, improve the rate of penetration. By sintering process, the sintering temperature is overall low in the first round test, the holding time is shorter, the second and the third round tests improve the sintering temperature and prolong the preservation time, which is advantageous to the alloying of blade material, play the synergy of different metal elements, and improve the matrix performance. But the sintering temperature and sintering pressure is unfavorably exorbitant to result in falling off with the whole of the matrix and the diamond, will happen impellers of blade. By the bit structure,6 teeth and 6 nozzle have greater surface area than4 teeth and 4 nozzle, which is advantageous to the blade cooling heat dissipation and rock powder on return, protection of blade and diamond. The three rounds of testing continuously strengthen gauge measures to weaken the inside and outside circular arc phenomenon of the bit lip surface, improve the bit life and aging. By comparing the three rounds of indoor test, the design of bit blade material being suitable for the condition of high speed/high line speed under high speed turbine can be established, including the followers: (l)choose a relatively soft blade material such as Cu-Sn based and Cu based bit, optimize Co base blade formula or increase the Co content of the blade material to be 20%; (2)use diamond scheme of small size or mixed medium with small size, such as mixed SPC210 with 30/50 diamond, and appropriately increase diamond concentration to be 120%; (3) appropriately improve the bit sintering temperature and prolong the time of heat preservation, choose the sintering temperature to be 1050℃ to 1080℃ and the holding time to be 7 min and lower the sintering pressure to be 15 MPa;(4) using the bit structure of 6 tooth and 6 nozzle and strengthen the gauge.In view of the slipping phenomenon when impregnated diamond bits drill in the working condition of low WOB/low specific pressure, a new way of adding pore-forming agent to the bits matrix to improve the cutter tooth surface roughness is presented to accelerate the matrix’s wear and improve bits’self-sharpening and drilling rate. The research results of the pore-forming mechanism of the selected type A and type X (Xi and X2) pore-forming agent show that the 2 type pore-forming agents both occur in chemical reaction in the pore formation process, generate the stomata, form permanent pore space and have the dual pore formation function. The research results of several mechanical properties and wear resistance of the blade material after adding pore-forming agent show that the mechanical properties and wear resistance of blade material will be reduced, but the drilling rate can be significantly improved, so the optimization quantity of pore former is 3% after comprehensive considering of the mechanics performance and drilling performance of blade material. The condition of the segments’ crown after friction and wear demonstrates that the pore-forming agents added have pore function. The physical and chemical behavior of pore-forming agents’pore-forming mechanism in chemical reactions is studied, such as the behavior of thermodynamics and chemical kinetics. The research of the three laws of thermodynamics shows that the chemical reactions of pore-forming role are all implemented forward, they can realize pore function. The research of chemical kinetics shows that chemical reaction rate of pore effect is related to temperature, rising temperature is beneficial to improve the pore rate, and hot pressing sintering is the high temperature condition which is beneficial to improve the chemical reaction rate. Through formula deduction, we can see that the bit blade material adding pore-forming agent can improve the labial surface roughness after friction and wear, accelerate wear of cutter tooth material, be beneficial to the diamond-setting ability and improve the rate of penetration.Based on the high-temperature friction heat problem when impregnated diamond bits drill in the working condition of high speed/high line speed, a new way of adding the graphite as solid lubricant to the bit blade material to reduce the cutter tooth surface friction coefficient is presented to reduce frictional heat. Graphite has special layer structure, it can make its C atoms in the same layer have excellent combination and be not easy to damage, and the binding force between layer and layer is weak, it meets the requirements of solid lubricant which prone to slip when having a shear force. The research results of the several mechanical properties and wear of the blade material after adding graphite show that the mechanical properties and friction coefficient between the friction pair of blade material will decrease. The analysis of the morphology of blade material after friction and wear draws the effect of lubrication and the drag reduction of graphite on the blade. The lubrication mechanism of graphite on the impregnated diamond bit blade is discussed in the macroscopic and microscopic, and the optimization quantity of graphite is 5% after comprehensively considering of the mechanics performance and frictional drag reduction effect of blade material. The research results of friction characteristics of the impregnated diamond bit under the working condition of high speed turbine show that the role is speed>WOB> pump output in the process of rock drilling.Lastly, the research of the field application of impregnated diamond bit is conducted in the paper, including in Guan Kou, Yuan Ba, Pu Guang and western Liao Ning. Analysis of the friction and wear of the bits show that the bits mainly produce abrasive wear and erosion wear under the process condition, and the role of the drilling technical parameters in the friction and wear is high speed> or< big pump output> low WOB in the wear of diamond, large amount of pump> or< high speed> low WOB in blade wear, and the erosion wear caused by large amount of pump is connected with the structure of the bit. When there are no PDCs in the bit bottom lip surface, the fluid flow space is very small among the diamond in the bit bottom lip surface, the erosion wear of the matrix is weak and mainly continuous friction and wear. When there are some PDCs in the bit bottom lip surface, large amount of pump will cause strong erosion wear to the matrix. Due to the large and deeper flow channel of comprehensive impregnated diamond bit, the rigid body mainly produce erosion wear. Analysis of impregnated diamond bit blade material and diamond formula show that the conclusions of the field application and the results in the three rounds of indoor test are almost the same, and the part of larger particles diamond can be added in the blade material in order to increase cutter tooth abrasion resistance and aggressive under low WOB and high speed, and the blade material tenacity may be further improved. Analysis of the blade material manufacturing process show that we may choose pre alloy powder and hot isostatic pressing process, and combine cold forming with hot pressing sintering process.Overall, the research of the impregnated diamond bit blade materials based on high speed turbine drilling process conditions is conducted in the paper, the design scheme of blade material is established, including blade material formula, diamond parameter and the manufacturing technology of cutter tooth. The modification research of blade material is conducted based on the working condition of high speed turbine, including the research of type A and type X (X1 and X2) pore-forming agent which is suitable for drilling slipping in the conditions of low WOB/low specific WOB and the research of solid lubricant--graphite for high temperature friction heat in the condition of high speed/high line speed under high speed turbine, and the field application research is carried out finally, the desired goal is basically achieved in the paper. But the research also exists some shortage, we need to work further, mainly including the followers:(1) there is a certain gap between the three rounds of indoor research and field application about the drilling technology conditions, we need to improve test conditions such as the experiment environment and equipment to make indoor experiment and field application conditions as consistent as possible. (2) both the added pore-forming agent and solid lubricant can reduce the mechanical performance of blade material although they improve the bit drilling rate in the modification research, we need to study further how to effectively maintain or increase mechanical properties of the blade material after adding additives. (3) due to the limited field application research, the data of only 4 field area application is collected in the paper, we need to increase the field application data to come to the more representative and rational conclusion. |
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