Preparation of active MgO composite expansive agent and its effect on volume deformation performance of cement slurry during hydration

2021 ◽  
pp. 1-15
Author(s):  
Zhi-Gang Peng ◽  
Xiao-Feng Zhang ◽  
Qian Feng ◽  
Yong Zheng
Keyword(s):  
Cement Slurry ◽  
Volume Deformation ◽  
Expansive Agent

Nanosized Magnesium Oxide With Engineered Expansive Property for Enhanced Cement-System Performance

SPE Journal ◽  
2017 ◽  
Vol 22 (05) ◽  
pp. 1681-1689 ◽  
Author(s):  
Narjes Jafariesfad ◽  
Mette Rica Geiker ◽  
Pål Skalle
Keyword(s):  
Heat Treatment ◽  
Young’S Modulus ◽  
Magnesium Oxide ◽  
Young's Modulus ◽  
Oil Well ◽  
Cement Slurry ◽  
Expansive Agent ◽  
Cement System ◽  
Zonal Isolation

Summary The bulk shrinkage of cement sheaths in oil wells can result in loss of long-term zonal isolation. Expansive additives are used to mitigate bulk shrinkage. To compensate effectively for bulk shrinkage during the late plastic phase and the hardening phase of the cement system, the performance of the expansive additive needs to be regulated considering the actual cement system and placement conditions. This paper presents an introductory investigation on the potential engineering of nanosized magnesium oxide (MgO) (NM) through heat treatment for use as an expansive agent in oilwell-cement systems. In this study, the bulk shrinkage of a cement system was mitigated by introducing NM with designed reactivity to the fresh cement slurry. The reactivity of NM was controlled by heat treatment. A dilatometer with corrugated molds was used to measure the linear strain of samples cured at 40°C and atmospheric pressure. The effect of NMs differing in reactivity on tensile properties of cement systems cured for 3 days at 40°C was examined by use of the flattened Brazilian test. The reactivity of the NM played a key role in controlling the bulk shrinkage of the cement system. Addition of only 2% NM by weight of cement (BWOC) with appropriate reactivity was sufficient to maintain expansion of the cement system. Adding NM to the cement system also resulted in improved mechanical flexibility. The NM with highest reactivity caused the largest reduction in Young's modulus at 3 days and, in general, the ratio of tensile strength to Young's modulus improved through the addition of NM to the cement system. Our work demonstrates that controlling the reactivity of the additive is a promising method to mitigate bulk shrinkage of cement systems and thereby to sustain the mechanical properties of the cement sheath in the oil well at an acceptable level.

scholarly journals Effect of expansive agent and internal curing agent on crack resistance of C50 silica fume wet-mix shotcrete

2019 ◽  
Vol 11 (1) ◽  
pp. 168781401881916 ◽  
Author(s):  
Feng Wei Ning ◽  
Yue Bo Cai ◽  
Yin Bai ◽  
Bo Chen ◽  
Feng Zhang
Keyword(s):  
Relative Humidity ◽  
Crack Resistance ◽  
Silica Fume ◽  
Stress Test ◽  
High Strength ◽  
Internal Curing ◽  
Ring Test ◽  
Curing Agent ◽  
Volume Deformation ◽  
Expansive Agent

High-strength shotcrete is always needed to strengthen rock support. However, it will reversely increase the crack risk. Crack normally goes against the durability and shortens the service life of shotcrete. The objective of this article was to improve the crack resistance of shotcrete with expansive agent and internal curing agent. C50 shotcrete with 10% of silica fume was taken as reference mix composition. Ring test and thermal stress test simulating actual temperature, relative humidity, and constraint were carried out to directly assess crack resistance. Restrained deformation, autogenous volume deformation, and pore structure were measured to study how expansive agent and internal curing agent resisted crack. The results indicated that 4% of expansive agent was enough to improve crack resistance of C50 shotcrete. It could fill internal pores and produce compressive pre-stress at earlier age which could be used to compensate shrinkage at later age. Furthermore, the crack resistance of C50 shotcrete could be further promoted when internal curing agent was employed together with expansive agent. The internal curing agent was able to reduce auto-shrinkage by decreasing the loss of internal relative humidity. In addition, it could also enhance the hydration degree of expansive agent, which would strengthen the role of expansive agent on resisting crack.

scholarly journals Effects of Shrinkage Reducing Agent and Expansive Admixture on the Volume Deformation of Ultrahigh Performance Concrete

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Su Anshuang ◽  
Qin Ling ◽  
Zhang Shoujie ◽  
Zhang Jiayang ◽  
Li Zhaoyu
Keyword(s):  
Compressive Strength ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Reducing Agent ◽  
Cementitious Material ◽  
Volume Deformation ◽  
Air Content ◽  
Expansive Agent ◽  
Reduction Effect ◽  
Shrinkage Reducing Agent

This paper investigated the influences of shrinkage reducing agent and expansive admixture on autogenous and drying shrinkage of ultrahigh performance concrete (UHPC) containing antifoaming admixture. The shrinkage reducing agent was used at dosage of 0.5%, 1%, and 2% and the expansive admixture was used at dosage of 2% to 4% by mass of cementitious material. The results show that the air content of UHPC increases with the higher addition of shrinkage reducing agent and expansive admixtures. However, the fluidity, compressive strength, and shrinkage of UHPC exhibit a declining tendency. The usage of expansive agent at dosage of 4% significantly reduces the shrinkage of UHPC. The 7-day autogenous shrinkage was decreased by 16.0% and 28-day drying shrinkage was decreased by 29.5%, respectively. Shrinkage reducing agent at dosage of 2% reduced the 7-day autogenous shrinkage by 44.3% and 28-day drying shrinkage by 50.2%. Compared with expansive admixture, shrinkage reducing agent exhibits more efficient shrinkage reduction effect on UHPC.

Autogenous Volume Deformation of Concrete due to MgO under the Temperature History of a Diversion Tunnel Concrete

2013 ◽  
Vol 357-360 ◽  
pp. 1399-1404 ◽  
Author(s):  
Fei Guo ◽  
Jia Ping Liu ◽  
Qian Tian ◽  
Ting Yao ◽  
Shou Zhi Zhang
Keyword(s):  
Temperature Rise ◽  
Volume Expansion ◽  
Real Structure ◽  
Temperature History ◽  
Temperature Decrease ◽  
Volume Deformation ◽  
Diversion Tunnel ◽  
Expansive Agent ◽  
History Of ◽  
Dam Concrete

Using MgO type expansive agent is considered as a convenient and effective method to reduce cracks in dam concrete, but the research on autogenous volume deformation of concrete with MgO type expansive agent under the temperature history of real structure is still unclear. In this paper, the temperature history of a diversion tunnel concrete was selected to discuss the autogenous volume deformation of concrete with different activities and dosages of MgO type expansive. The results showed that the autogenous volume expansion of concrete with MgO type expansive agent increased with the content and the activity of MgO type expansive agent. The expansion values of concrete with the content of 4%, 5% and 6% MgO type expansive agent are 51×10-6, 85×10-6 and 105×10-6 in temperature rise stage, and 43×10-6, 56×10-6 and 71×10-6 in temperature decrease stage. The expansion values of concrete with the activity 31s, 138s and 240s MgO type expansive agent are 36×10-6, 51×10-6 and 66×10-6 in temperature rise stage, and 32×10-6, 43×10-6 and 62×10-6 in temperature decrease stage. After 150d the autogenous volume deformation due to MgO type expansive agent did not increase any more.

Microstructure and Strength Characteristics Analysis of Shrinkage-Compensating Shotcrete

2011 ◽  
Vol 287-290 ◽  
pp. 1247-1251 ◽  
Author(s):  
Wei Huang ◽  
Qin Yong Ma
Keyword(s):  
Portland Cement ◽  
Steel Fiber ◽  
Concrete Strength ◽  
Strength Properties ◽  
Strength Characteristics ◽  
Micro Structure ◽  
Cement Slurry ◽  
Expansive Agent ◽  
Characteristics Analysis ◽  
Mineral Compositions

Due to the easy cracking of shotcrete, shrinkage-compensating shotcrete is researched and its micro-structure and strength properties are analyzed. Firstly, cement slurry is made by CSA, accelerating agent and two different cements. When hydrated 3 days and 28 days , hydration products of cement slurry are analyzed by SEM and XRD in feature, crystal characteristics and mineral compositions. The compatibility of the two different cements and admixtures is studied in apparent characteristics, and the fact that Portland cement is more suitable for making shrinkage-compensating shotcrete is obtained. Then, mechanical properties of concrete which consists of Portland cement, expansive agent and steel fiber are did to analyze the influence of strength characteristics caused by mix amount of expansive agent and steel fiber. The results show that the compression strength and tensile strength of concrete improve with the increasing mix of steel fiber. Incorporation of the expansive agent is greater impact on concrete strength, when mix amount of expansive agent is 8%, strength properties are the best. When mix amount of steel fiber is 1.0% and expansive agent is 8%, the effect of cooperative enhancement is the best.

scholarly journals Experimental Study on Sulfate Attack Resistance of Cement Slurry with UEA Expansive Agent

2019 ◽  
Vol 136 ◽  
pp. 03012
Author(s):  
Ganggang XU ◽  
Xiaodong WANG ◽  
Hai WANG
Keyword(s):  
Physical And Mechanical Properties ◽  
Sulfate Solution ◽  
Solution Concentration ◽  
Immersion Test ◽  
Sulfate Attack ◽  
Mineral Admixtures ◽  
Cement Slurry ◽  
Factors Affecting ◽  
Expansive Agent ◽  
Working Face

Sulfate attack was one of the most important factors affecting the durability of cement slurry in mine corrosive environment. For water stopping and reinforcement projects in wellbore or working face under sulfate erosion environment, mineral admixtures were often used to improve the sulfate resistance of cement slurry. The physical and mechanical properties of cement mortar with 0, 4%, 8%, 12% and 16% UEA expansive agent content under the conditions of 0.6%, 3% and 15% sodium sulfate solution concentration were investigated through the full immersion test for 19 months in the laboratory. The results showed that the strength of mortar specimens decreased with the increase of UEA expansive agent content, but in the sulfate attack environment, the ability to resist sulfate attack could be significantly improved. In order to ensure the early strength of mortar and reduce the cost, the best effect of UEA expansion agent was 4%.

Adding an expansive agent to increase the toughness of steel fibre reinforced concrete

2019 ◽  
Vol 26 (4) ◽  
pp. 197-208
Author(s):  
Leo Gu Li ◽  
Albert Kwok Hung Kwan
Keyword(s):  
Reinforced Concrete ◽  
Steel Fibre ◽  
The Other ◽  
Fibre Reinforced Concrete ◽  
Test Results ◽  
Compressive Properties ◽  
Shrinkage Cracking ◽  
Steel Fibre Reinforced Concrete ◽  
Expansive Agent ◽  
Concrete Matrix

Previous research studies have indicated that using fibres to improve crack resistance and applying expansive agent (EA) to compensate shrinkage are both effective methods to mitigate shrinkage cracking of concrete, and the additions of both fibres and EA can enhance the other performance attributes of concrete. In this study, an EA was added to fibre reinforced concrete (FRC) to produce concrete mixes with various water/binder (W/B) ratios, steel fibre (SF) contents and EA contents for testing of their workability and compressive properties. The test results showed that adding EA would slightly increase the superplasticiser (SP) demand and decrease the compressive strength, Young’s modulus and Poisson’s ratio, but significantly improve the toughness and specific toughness of the steel FRC produced. Such improvement in toughness may be attributed to the pre-stress of the concrete matrix and the confinement effect of the SFs due to the expansion of the concrete and the restraint of the SFs against such expansion.

COMPARATIVE ANALYSIS OF THE INFLUENCE OF NATURAL AND ANTHROPOGENIC FACTORS ON THE VISTULA SPIT FOREDUNE EROSION (THE BALTIC SEA

2017 ◽  
Author(s):  
Evgenii Burnashov ◽  
Evgenii Burnashov ◽  
Konstantin Karmanov ◽  
Konstantin Karmanov
Keyword(s):  
Baltic Sea ◽  
Laser Scanning ◽  
Essential Element ◽  
Base Station ◽  
Beach Erosion ◽  
Single Frequency ◽  
Anthropogenic Factors ◽  
The Baltic Sea ◽  
Volume Deformation ◽  
The Baltic

The study gives quantitative estimation of natural landforms sensitivity of accumulative type coasts exposed to human influence. Foredune is an essential element of a morphological structure of thebarrier spits located at the Baltic Sea sand coasts. The study compares contribution of the beach erosion and deflation (soil drifting) to the foredune degradation on the sea shore of the barrier spit with or without the recreational impact. The analysis is performed for three typical polygons located on the Russian part of the Vistula Spit. Chosen polygons present shore segments with various intensity of tourism: visitors from the village, unregulated camp tourism, and nearly natural conditions. Detailed geodesic survey was carried out on these three polygons (length 515 m, 265 m, and 521 m respectively; total area – 125000 m2) in July of 2015. It was done with single-frequency geodesic GPS Trimble 5700L1 (base station) and TrimbleR3 (rover). Two DEMs were developed using the results of laser scanning of 2007 and the survey of 2015. Volume deformation for whole polygons and its particular parts (beach and foredune ridge) was made by comparison of the DEMs. In the case of touristic load the effect of deflation is 5-15 times higher than the marine erosion of foredune edge. If not affected by an anthropogenic factor the foredune erosion is caused mainly by the sea, and its impact is 6 times higher than that of the natural deflation.

PRESSURE CONTROL SYSTEM AT CEMENTATION OF WELLS

2017 ◽  
pp. 62-67
Author(s):  
V. G. Kuznetsov ◽  
O. A. Makarov
Keyword(s):  
Control System ◽  
Oil And Gas ◽  
Pressure Control ◽  
Poor Quality ◽  
Technical Solution ◽  
Cement Slurry ◽  
Automated Control ◽  
Injection Speed ◽  
Pressure Control System ◽  
Effective Life

At cementing of casing of oil and gas wells during the process of injecting of cement slurry in the casing column the slurry can move with a higher speed than it’s linear injection speed. A break of continuity of fluid flow occurs, what can lead to poor quality isolation of producing formations and shorten the effective life of the well. We need to find some technical solution to stabilize the linear velocity of the cement slurry in the column. This task can be resolved with an automated control system.

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