The shrinkage behavior of high performance cement concrete made from Portland cement, ultra fine granulated blast furnace slag and pulverized fly ash with addition of superplasticizer at different temperatures from am...The shrinkage behavior of high performance cement concrete made from Portland cement, ultra fine granulated blast furnace slag and pulverized fly ash with addition of superplasticizer at different temperatures from ambient temperature to 120 ℃ under different seuliug conditions was investigated by means of length change measurement on cylindrical concrete specimens along with curing age. Results show that drying shrinkage deformations of titled concrete specimens increased rapidly as the curing temperature rose. The development of dryiing shrinkage deformatian can be efficiently controlled with the aid of aluminum tape sealing as compared with the unsealed specimens, especially when the curing temperature is below 60℃ , although it will increase dramatically when the curing temperature is elevated to above 90%＂ . Polymer coating on concrete specimens showed a similar effect on the control of drying shrinkage as the sealing operation with aluminum tape.展开更多
To effectively solve the problem of lost circulation and well kick frequently occurring during the drilling of abnormally high temperature and pressure fractured-vuggy reservoirs in the Tazhong block, a rigid particle...To effectively solve the problem of lost circulation and well kick frequently occurring during the drilling of abnormally high temperature and pressure fractured-vuggy reservoirs in the Tazhong block, a rigid particle material, GZD, with high temperature tolerance, high rigidity(> 8 MPa) and low abrasiveness has been selected based on geological characteristics of the theft zones in the reservoirs. Through static pressure sealing experiments, its dosage when used alone and when used in combination with lignin fiber, elastic material SQD-98 and calcium carbonate were optimized, and the formula of a new type(SXM-I) of compound lost circulation material with high temperature tolerance and high strength was formed. Its performance was evaluated by compatibility test, static sealing experiment and sand bed plugging experiment. The test results show that it has good compatibility with drilling fluid used commonly and is able to plug fractures and vugs, the sealed fractures are able to withstand the static pressure of more than 9 MPa and the cumulative leakage is 13.4 mL. The mud filtrate invasion depth is only 2.5 cm in 30 min when the sand bed is made of particles with sizes between 10 mesh and 20 mesh. Overall, with good sealing property and high temperature and high pressure tolerance, the lost circulation material provides strong technical support for the safety drilling in the block.展开更多
Aluminum coatings were sprayed on the substrate of steel Q235 by arc spraying. The test samples of Q235, Al coatings and Al coatings with seal coat were placed in box type electric resistance furnace at 400, 500,600, ...Aluminum coatings were sprayed on the substrate of steel Q235 by arc spraying. The test samples of Q235, Al coatings and Al coatings with seal coat were placed in box type electric resistance furnace at 400, 500,600, 650 ℃ when their oxidation behaviors were studied. And their oxidation kinetics curves were protracted. Microstructure, microhardness, bond strength and distribution of section elements were investigated by optical microscope(OM), Vickers microhardness instrument, electric tensile test machine and EPMA. Al coatings and Al coatings with seal coat can enhance the oxidation-resistance of substrate under 500 ℃. The latter has the best corrosion resistance. The coatings can't protect the substrate against oxidation above 600 ℃. After a long time corrosion there is enriched oxygen element at interface.展开更多
The purpose of this investigation was to evaluate the microstructure,high-temperature oxidation behaviour,and hardness of a seal coating under controlled exposures at 750℃with different exposure times.The results rev...The purpose of this investigation was to evaluate the microstructure,high-temperature oxidation behaviour,and hardness of a seal coating under controlled exposures at 750℃with different exposure times.The results reveal that the main phases in the coating are Ni,FeNi3,and hexagonal BN,withα-Al_(2)O_(3)peaks appearing after 2-h oxidation.As the exposure time increases,the diffraction peak intensity ofα-Al_(2)O_(3)begins to decrease and Cr_(2)O_(3)peaks appear after 200 h.After 1000 h,Cr_(2)O_(3)becomes dominant with only small amounts ofα-Al_(2)O_(3)remaining.The high-temperature oxidation process of the coating includes three stages:the fast stage,transition stage,and slow stage.The oxidation rate is constant in each stage,and in the fast stage and slow stages with values of7.9×10^(-4)and 8.37×10^(-5)mg^(2)·cm^(-4)·s^(-1),respectively.Initially,α-Al_(2)O_(3)forms near the pores in the coating,followed by the formation of Cr_(2)O_(3).As the exposure time increases,oxidation penetrates into the interior of the coating along phase boundaries to form island-shaped inner oxide layers with high concentrations of Cr,Ni,and Fe.Additionally,hardness increases with increasing oxide percentage.展开更多
文摘The shrinkage behavior of high performance cement concrete made from Portland cement, ultra fine granulated blast furnace slag and pulverized fly ash with addition of superplasticizer at different temperatures from ambient temperature to 120 ℃ under different seuliug conditions was investigated by means of length change measurement on cylindrical concrete specimens along with curing age. Results show that drying shrinkage deformations of titled concrete specimens increased rapidly as the curing temperature rose. The development of dryiing shrinkage deformatian can be efficiently controlled with the aid of aluminum tape sealing as compared with the unsealed specimens, especially when the curing temperature is below 60℃ , although it will increase dramatically when the curing temperature is elevated to above 90%＂ . Polymer coating on concrete specimens showed a similar effect on the control of drying shrinkage as the sealing operation with aluminum tape.
基金Supported by the China National Science and Technology Major Project(2011ZX05042-002-001)
文摘To effectively solve the problem of lost circulation and well kick frequently occurring during the drilling of abnormally high temperature and pressure fractured-vuggy reservoirs in the Tazhong block, a rigid particle material, GZD, with high temperature tolerance, high rigidity(> 8 MPa) and low abrasiveness has been selected based on geological characteristics of the theft zones in the reservoirs. Through static pressure sealing experiments, its dosage when used alone and when used in combination with lignin fiber, elastic material SQD-98 and calcium carbonate were optimized, and the formula of a new type(SXM-I) of compound lost circulation material with high temperature tolerance and high strength was formed. Its performance was evaluated by compatibility test, static sealing experiment and sand bed plugging experiment. The test results show that it has good compatibility with drilling fluid used commonly and is able to plug fractures and vugs, the sealed fractures are able to withstand the static pressure of more than 9 MPa and the cumulative leakage is 13.4 mL. The mud filtrate invasion depth is only 2.5 cm in 30 min when the sand bed is made of particles with sizes between 10 mesh and 20 mesh. Overall, with good sealing property and high temperature and high pressure tolerance, the lost circulation material provides strong technical support for the safety drilling in the block.
文摘Aluminum coatings were sprayed on the substrate of steel Q235 by arc spraying. The test samples of Q235, Al coatings and Al coatings with seal coat were placed in box type electric resistance furnace at 400, 500,600, 650 ℃ when their oxidation behaviors were studied. And their oxidation kinetics curves were protracted. Microstructure, microhardness, bond strength and distribution of section elements were investigated by optical microscope(OM), Vickers microhardness instrument, electric tensile test machine and EPMA. Al coatings and Al coatings with seal coat can enhance the oxidation-resistance of substrate under 500 ℃. The latter has the best corrosion resistance. The coatings can't protect the substrate against oxidation above 600 ℃. After a long time corrosion there is enriched oxygen element at interface.
基金financially supported by the National Natural Science Foundation of China(No.51571031)。
文摘The purpose of this investigation was to evaluate the microstructure,high-temperature oxidation behaviour,and hardness of a seal coating under controlled exposures at 750℃with different exposure times.The results reveal that the main phases in the coating are Ni,FeNi3,and hexagonal BN,withα-Al_(2)O_(3)peaks appearing after 2-h oxidation.As the exposure time increases,the diffraction peak intensity ofα-Al_(2)O_(3)begins to decrease and Cr_(2)O_(3)peaks appear after 200 h.After 1000 h,Cr_(2)O_(3)becomes dominant with only small amounts ofα-Al_(2)O_(3)remaining.The high-temperature oxidation process of the coating includes three stages:the fast stage,transition stage,and slow stage.The oxidation rate is constant in each stage,and in the fast stage and slow stages with values of7.9×10^(-4)and 8.37×10^(-5)mg^(2)·cm^(-4)·s^(-1),respectively.Initially,α-Al_(2)O_(3)forms near the pores in the coating,followed by the formation of Cr_(2)O_(3).As the exposure time increases,oxidation penetrates into the interior of the coating along phase boundaries to form island-shaped inner oxide layers with high concentrations of Cr,Ni,and Fe.Additionally,hardness increases with increasing oxide percentage.
