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During acidizing process in a gas field, leakage of 80SS anti-sulfur tubing occurred.The main reasons for failure of the tubing have been investigated based on analysis techniques of chemical composition analysis,Optical Microscopy (OM), Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS) , X-ray Diffraction (XRD) and mechanical test. The results show that composition and mechanical properties of the tubing were all in accordance with the corresponding requirements of API Spec 5CT standards. Furthermore,leakage of tubing from inner wall was caused by combined impacts of acid corrosion, H2S corrosion, low PH value, high temperature and a certain pressure. Meanwhile, Low concentration of corrosion inhibitor was also one of the factors of corrosion perforation.

The 110 Ksi tubing failed in use when reservoir acidification reconstruction and production testing were performed in an oil well, which were longitudinal cracking of coupling. Failure analysis was conducted on the coupling. The failure zone was studied by means of macroscopic analysis, metallographic, scanning electronic microscope,energy dispersive spectrometer and X-ray diffraction analysis etc. The results indicated that the failure of the coupling is caused by stress corrosion cracking (SCC). SCC initiated from the exterior surface of coupling and displayed the fracture feature of intergranular crack propagation. The corrosion products at the grain boundaries were found to be mainly some oxides. The failure was in connection with the completion fluid composition, which are mainly nitrates.

Objective: To study the muscle injury, inflammatory response and bone metabolism after paravertebral muscle space and minimally invasive percutaneous approach surgeries for thoracolumbar fracture. Methods: A total of 92 patients with thoracolumbar fractures who were treated in Baoji Central Hospital between May 2015 and January 2017 were selected and randomly divided into paravertebral group and minimally invasive percutaneous group who accepted pedicle screw fixation under different approaches. Before operation as well as 1 d and 3 d after operation, serum was collected to determine the contents of creatase, inflammatory reaction molecules and bone metabolism indexes. Results: Serum Myo, CK, LDH, TNF-α, MCP-1, HMGB-1, CRP, IL-1β, OC, OPG, PICP and PINP levels of both groups 1 d and 3 d after operation were significantly higher than those before operation while TRACP5b, RANKL, CTX and NTX levels were significantly lower than those before operation, and serum Myo, CK, LDH, TNF-α, MCP-1, HMGB-1, CRP, IL-1β, TRACP5b, RANKL, CTX and NTX levels of paravertebral group 1 d and 3 d after operation were significantly lower than those of minimally invasive percutaneous group while OC, OPG, PICP and PINP levels were significantly higher than those of minimally invasive percutaneous group. Conclusion: Paravertebral muscle space surgery for thoracolumbar fracture is more effective than minimally invasive percutaneous surgery in reducing muscle injury and inflammatory response, and improving bone metabolism.

The fractured drill pipe was investigated by means of non-destructive testing, chemical composition analysis, optical microscope, material property testing machine and SEM with EDS. The results showed that fracture of drill pipe body was hydrogen sulfide stress corrosion cracking. High strength, high hardness, and stress corrosion sensitivity of the drill pipe material were important reasons leading to failure.

The fracture failure research on a drilling jar’s top joint was carried out on basis of correlative theories and tests. Macroscopic analysis, dimension measurement and nondestructive testing were done for failure joint. The material’s chemical and physical properties were tested. The drilling strings assembly was analyzed specially and the bending strength ratio between top joint and adapter joint was calculated detailedly. The results showed that the drilling jar’s joint was broken because of fatigue induced by irrational drilling strings assembly and improper matching between top joint and adapter joint. The joint’s fatigue life was reduced further because material’s impact toughness is less than standard value.

In order to find the corrosion cause of petroleum casing premium connection material, the fixture was design to simulate material enduring compressive stress, and the fixture was put in high temperature autoclave, and the corrosion rate of two kind casing material(carbon steel and stainless steel) enduring compressive stress were test in H2S and CO2 and Cl- water solution. The result was that compressive stress accelerated the corrosion of petroleum casing steel, and when compressive stress was greater than the value half as the yield strength the corrosion rate increased quickly.

The buttress thread connection was used in deep well or ultra-deep well widely because of its high joint efficiency. Pullout failure scarcely happen on buttress premium thread connection with great joint strength and good sealing property. Direct evidences about connection dropout couldn’t get in most cases by reason of casing string had fallen into well or casing string had been concreted in formation by cement. Now the difficulty of analysis on pullout is higher and higher. A buttress premium thread casing joint had pulled out at mill end of coupling in a straight well and dropout casing string couldn’t get out of the well. Research on this pullout case was carried out combining relative theories with tests. Macroscopic analysis and dimension measurement were done for dropout coupling. The material’s physical and chemical properties were checked. Thread inspection and full-scale tests were done for two casing simples that are same lot with pullout. Metallograph analysis was carried out on load flank and guide flank in box thread of pullout coupling and same lot new coupling. The results showed that dropout failure was ascribe to inadequate make-up torque at mill end of pullout coupling and complex downhole condition and improper handling in the oil field. On the other hand joint’s strength decline on the effect of unsuitable heat treatment to coupling and greatly uneven black crested pin thread around circumference. The pertinence measures were laid down at the end of this passage.

A new drill pipe steel microalloyed with 0.04 w.t.% Nb was designed to meet the needs of drilling operation in super-deep wells, and the precipitation behavior of Nb during temper was studied in detail. The results show the austenitic grain can be refined by the addition of 0.04 w.t.% Nb, and the steel has a high yield strength of 1192MPa, high tensile strength of 1226MPa and high impact absorbing energy of 137J when the steel is quenched at 900°C and tempered at 550°C, moreover, the volume fraction and dimension of precipitates increases with increasing temper temperature. When the new steel is tempered at 550°C, the new steel has the best comprehensive performance due to the fine dispersed precipitates. The mechanical properties of the new steel are much better than that of the common drill pipe steel.

The expansion evaluation device for solid expandable tubular (SET) was researched and designed considering some questions of too little expansion force to flareout SET for a great many other simple expansion devices, too little expansion speed, improper expansion process that don’t match the truth and etc.. The SET can be checked and evaluated through expansion test simulating oil field fact on the expansion evaluation device. Using this device the expansion test can be carried out by only mechanical stretching force or only hydraulic pressure or the combination of mechanical tensile force and hydraulic power. Practice shows that the evaluation devic is characterized by low cost, economic and pragmatic and high reliability. On the other hand some other roles can be get by making use of evaluation device, for example research on deformation law for steel pipe, choice and development of SET’s material, optimization design of expansion cone, study on expansion technology and etc.. The expansion evaluation device will make a great role on promoting SET quality and advance the localization process of chinese SET industry.

This paper studies properties of concrete under the action of water-reducing retarder and expansive agent; gives the optimal design calculation method of cooling water pipe in the construction technology: mainly considering pipe’s diameter, distance, cooling water’s flow, temperature, time etc; studies the optimization to the concretes construction method. Midas/Civil, one finite element analysis soft-ware, analyses mass concrete construction of the whole process of the temperature field and stress field in the numerical simulation, considering the admixtures and construction technology. The results show that commonuse of admixtures and reasonable construction technology are the important means of controlling cracks.

To discuss the therapeutic effects of the atlantoaxial pedicle screw system fixation in treatment of atlantoaxial instability.From June 2003 to March 2010, 32 patients with atlantoaxial instability were treated by atlantoaxial pedicle screw system fixation, included 21 males and 11 females wiht an average age of 42.5 years old ranging from 28 to 66 years. Among them, 18 cases were odontoid process fractures, 7 were congenital dissociate odontoid process, 4 were Jefferson fracture combined with odontoid fracture, 3 were rheumatic arthritis causing atlantoaxial instability. All patients suffered from the atlantoaxial subluxation and atlantoaxial instability. The JOA score ranged from 4 to 14 (means 9.1 +/- 0.3) before operation. The patients had some image examination including the X-ray of cervical vertebrae (include of dynamic position film), spiral CT 3D reconstruction and/or MRI. The position of pedicle screw system implantation,the angle of pedicle screw system implantation and screw length were measured. Operating skull traction. Operation undewent general anesthesia, implanted the pedicle screw, reduction and bone fusion under direct vision. The bone was fixated between posterior arch of atlas and lamina of axis by the lateral combination bended to posterior.One hundred and twenty-eight atlantoaxial pedicle screws were implanted in 32 patients. No patient had the injure of spinal cord, nerve root and vertebral artery. All patients were followed-up from 6 to 48 months (averaged 16 months). After operation, the JOA score ranged from 11 to 17 (averaged 15.9 +/- 0.2), improvement rate was 86.1%. The fracture of odontoid process were healing completely. All fusion bone were combinated. The internal fixation wasn't loosening and breaking.The atlantoaxial pedicle screw system fixation was effective method to treat atlantoaxial instability. The method had many advantages, such as provide rigid and short segment fixation, safe and simple, high fusion rate. The method was worth in clinical application.