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Copyright of Natural Gas & Oil is the property of Editorial Department of Natural Gas & Oil and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Drilling Fluid & Completion Fluid is the property of Drilling Fluid & Completion Fluid Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cementing in long sealing section of deep well is faced with the problem of long thickening time in high temperature section and long solidification time in low temperature section. Based on the concept of molecular structure activity changes during the formation/dissociation of amphiphilic polymer self-assembly structure. AMPS, unsaturated carboxylic acid (PA) and cationic monomer (CM) are used to synthesis a temperature responsive intelligent retarder TRIR by RAFT polymerization. Response surface methodology was used to optimize the synthetic process conditions of the polymer. The optimal process conditions were determined as follows: monomer concentration 28.7%, initiator dosage 0.6%, synthesis temperature 50 ℃, and reaction pH 4.5. The structure and thermal stability of the polymer were characterized by infrared spectroscopy and thermogravimetric analysis, and its retarding performance was evaluated. The results show that TRIR has excellent temperature resistance, the thickening time at 200 ℃ can reach 356 min under 4.0% (liquid) dosage, and the retarding property is significantly enhanced with the temperature rise in the range of 120～ 180 ℃. The thermal response polymer proposed in this paper can provide a new idea for the development of intelligent polymer in the future petrochemical field. [ABSTRACT FROM AUTHOR]

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Under low confining pressures, a hard brittle mudstone is easy to dilate before the stress acted on the mudstone reaches its peak value. When the stress is greater than the dilation strength of the shale, the weakening of the mudstone by the hydration of the drilling fluid becomes fast and outstanding, resulting in borehole collapse. To avoid borehole collapse, a reasonable mud weight should be used. Through laboratory experiment and theoretical analysis, studies were conducted on the factors such as the fabric characteristics, hydrophysical properties, deforming patterns and strength criteria of hard brittle mudstones, as well as the change of strengths of mudstones after unloading prestress in a drilling fluid. A computation model and parameter computing method based on rock dilation strength criteria were developed for the collapse pressure of a borehole penetrating hard brittle mudstones, and a case study was conducted. The study results show that the mud weight is greater than the collapse pressure calculated on the basis of peak strength criteria and is lower than the collapse pressure calculated on the basis of dilation strength criteria, the formation around the borehole is in a state of dilation, and stress-induced micro fractures are generated around the wellbore, which stimulates drilling fluid hydration, and this is the root cause for borehole collapse. Based on this knowledge, mud weight determined on the basis of dilation strength criteria is more reasonable. [ABSTRACT FROM AUTHOR]

Extended reach wells have been widely used in oil and gas reservoir exploitation in deep formations. However, a series of downhole problems, such as inefficient hole cleaning, back pressure, and pipe sticking, are also encountered. To better guide hole cleaning, the dynamic characteristics of cuttings transport in long open hole section of ultra-deep extended reach wells must be studied further. According to the law of mass conservation and the momentum theorem, a two-layer dynamic cuttings transport model of extend reach wells was established, considering the actual hole trajectory, fluid pressure drop, and particle diffusion in the suspension layer. The model was solved by the finite difference method and verified by the experimental results in the existing literature. The process of drilling and well washing was simulated and the influence of the drilling fluid flow rates, the drilling fluid density, the rate of penetration (ROP), and the wellbore diameter on cuttings transport were analyzed. Research results demonstrate that, under drilling conditions, cuttings are difficult to deposit in the section with a small inclination angle, the degree of hole cleaning increases with the flow rates and the drilling fluid density, and the smaller wellbore diameter is, the lower the ROP is, which is helpful in hole cleaning. Under well washing conditions, the smaller the inclination angle of the well is, the worse the erosion effect is, and the smaller wellbore diameter is, the higher the efficiency of cuttings transport is, the degree of hole cleaning increases with the flow rates and the drilling fluid density. The research results have a guiding significance for ensuring the good hole cleaning of ultra-deep extended reach wells. [ABSTRACT FROM AUTHOR]

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Continuous gas lift is an important drainage and production measure for horizontal gas wells with large water production. According to the characteristics of on-site normal and inverse circulation of air lift, in order to obtain the gas-liquid two-phase flow law in a circular pipe under reverse lift and the law in the annulus under forward lift, the experiments of gas-liquid two-phase pipe flow in wellbore were carried out with water and air in annular pipe with casing inner diameter of 127.3mm, tubing outer diameter of 73mm and test pipe with inner diameter of 60mm.The wellbore flow law of low-pressure effusion gas well during gas lift was studied and analyzed. The effects of gas and liquid phase volume flow and gas injection mode on wellbore pressure drop and liquid holdup were analyzed. Through comparison, it is found that under the same gas-liquid flow rate, the liquid holdup in inverse circulation of air lift is smaller than that in normal circulation of air lift; The pressure drop under different lifting modes shows an opposite trend with the increase of gas volume. The wellbore pressure drop during inverse circulation of air lift is greater than that under normal circulation of air lift under the same working condition. Therefore, for gas wells with large liquid production, the normal circulation of air lift method is recommended for drainage and gas production. [ABSTRACT FROM AUTHOR]

The main influencing factors of perforation completion on oil well productivity are hole density, hole diameter, hole depth and hole phase. The optimal design of perforation parameters based on the optimal oil well productivity is one of the key technologies to improve the productivity of perforated wells. Based on the semi-analytical model of perforated well productivity, the finite element analysis method was used to simulate the productivity of perforated well, and the numerical simulation results were analyzed according to the orthogonal experimental method. The results show that the productivity ratio increases with the increase of hole depth, and the slope is large when the hole depth is small. When the perforation depth exceeds the depth of drilling pollution zone, the inflection point of the curve occurs, and the slope becomes smaller and flattened. With the increase of hole diameter, the productivity ratio gets greater. Considering the problem of casing strength in the actual perforation process, the hole diameter should be taken as maximum as pos-sible under the condition of ensuring casing strength. The productivity ratio increases while the upward trend of productivity ratio decreases with the increase of pore density. With the increase of phase angle, the productivity ratio decreases. When the phase angle changes from 60° to 90°, the productivity increases greatly. The productivity has little change when the phase angle changes between 90° and 180°. The primary and secondary influencing factors are found by comparing the value of range R. This study provides guidance for the optimization of perforation parameters. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Petrochemical Universities / Shiyou Huagong Gaodeng Xuexiao Xuebao is the property of Journal Editorial Department Of Liaoning Shihua University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Elastic-strain-softening-plastic deformation is a typical mechanical behavior in the process of rock compression. Considering the strain-softening characteristics of rock is helpful to correctly evaluate the wellbore stability. The full stress-strain curves of the rock sample are obtained by carrying out the triaxial compression experiments, furthermore, the strength parameters of the rock sample are analyzed based on the Mohr-Coulumb strength failure criterion and verified by numerical simulation, then the changing law of the strength parameters of the rock sample with the plastic deformation is obtained. The finite difference software FLAC3 D is used to establish the borehole model, and the strain softening model is used to calculate the distribution of the plastic zone around the borehole. It is shown that the range of the plastic zone around the borehole is larger when considering the strain softening behavior compared with the ideal elastic-plastic model, as a result, the wellbore is more prone to instability. The study has guiding significance for determining the safety window of drilling fluid density and guiding drilling operation. [ABSTRACT FROM AUTHOR]

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)