scholarly journals Effect of Bentonite Prehydration Time on the Stability of Lightweight Oil-Well Cement System

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Stephen Adjei ◽  
Salaheldin Elkatatny ◽  
Abdulaziz Al-Majed
Keyword(s):  
Pore Space ◽  
Rheological Parameters ◽  
Chloride Salt ◽  
Oil Well ◽  
Sodium Bentonite ◽  
Particle Size Analyzer ◽  
Oil Well Cement ◽  
Petroleum Wells ◽  
The Stability ◽  
Well Cement

Lightweight cement systems are used in the weak intervals of petroleum wells. Sodium bentonite is used as an extender in lightweight oil-well cement systems as it prevents excess water and sedimentation of particles, thereby ensuring the formation of homogenous and stable cement sheaths. The extending ability of sodium bentonite is enhanced when prehydrated. However, the optimum bentonite prehydration time and its effect on the stability of lightweight cement systems have not been well established. The objective of this study is to investigate the optimum sodium bentonite prehydration time and correlate it to the stability of lightweight oil-well cement systems. Bentonite suspensions were prepared by vigorous preshearing at 12000 rpm for 5 minutes, followed by aging times of 0, 30, 60, and 120 minutes. The swelling behavior of bentonite was investigated using a laser particle size analyzer. The Herschel-Bulkley model was used to determine the rheological parameters of the experimentally measured shear stress vs. shear rate data of the aged suspensions. The effect of calcium chloride salt on aged bentonite suspensions was investigated. Density measurements and pore space analysis with the nuclear magnetic resonance (NMR) technique were used to investigate the homogeneity of cement-based cores. It was observed that bentonite swells with time and, after 30 minutes, the swelling is insignificant; however, the swelling property did not have any observed impact on the properties of cement systems designed with the bentonite aged at different times. In general, all the lightweight cement slurries exhibited similar properties, in terms of rheology, stability, and homogeneity, regardless of the bentonite prehydration time. These findings indicate that aging bentonite suspension after vigorous preshearing in lightweight cement design is unnecessary and would only contribute to nonproductive time.

Investigation of Dehydroxylated Sodium Bentonite as a Pozzolanic Extender in Oil-Well Cement

2021 ◽  
pp. 1-8
Author(s):  
Stephen Adjei ◽  
Salaheldin Elkatatny ◽  
Pranjal Sarmah ◽  
Gonzalo Chinea
Keyword(s):  
Heat Treatment ◽  
Compressive Strength ◽  
Fly Ash ◽  
Atmospheric Pressure ◽  
High Stability ◽  
Oil Well ◽  
Sodium Bentonite ◽  
Pozzolanic Material ◽  
Oil Well Cement ◽  
Well Cement

Summary Fly ash, which is a pozzolan generated as a byproduct from coal-powered plants, is the most used extender in the design of lightweight cement. However, the coal-powered plants are phasing out due to global-warming concerns. There is the need to investigate other materials as substitutes to fly ash. Bentonite is a natural pozzolanic material that is abundant in nature. This pozzolanic property is enhanced upon heat treatment; however, this material has never been explored in oil-well cementing in such form. This study compares the performance of 13-ppg heated (dehydroxylated) sodium bentonite and fly-ash cement systems. The raw (commercial) sodium bentonite was dehydroxylated at 1,526°F for 3 hours. Cement slurries were prepared at 13 ppg using the heated sodium bentonite as partial replacements of cement in concentrations of 10 to 50% by weight of blend. Various tests were done at a bottomhole static temperature of 120°F, bottomhole circulating temperature of 110°F, and pressure of 1,000 psi or atmospheric pressure. All the dehydroxylated sodium bentonite systems exhibited high stability, thickening times in the range of 3 to 5 hours, and a minimum 24-hour compressive strength of 600 psi. At a concentration of 40 and 50%, the 24-hour compressive strength was approximately 800 and 787 psi, respectively. This was higher than a 13-ppg fly-ash-based cement designed at 40% cement replacement (580 psi).

Development of Functional Polymer as Oil-Well Cement Retarder

2015 ◽  
Vol 814 ◽  
pp. 191-198 ◽  
Author(s):  
Xiu Jian Xia ◽  
Jin Tang Guo ◽  
Shuo Qiong Liu ◽  
Jian Zhou Jin ◽  
Yong Jin Yu ◽  
...  
Keyword(s):  
High Temperature ◽  
Ultrasonic Method ◽  
Strength Development ◽  
Cement Stone ◽  
Oil Well ◽  
Cement Slurry ◽  
Oil Well Cement ◽  
Cement Retarder ◽  
The Stability ◽  
Well Cement

In this study, a novel polymer retarder DRH-200LG was synthesized to solve the problems of retarding failure, strong dispersivity under high temperature and adverse impact on the strength development of cement stone. The composition of the polymer was confirmed by IR, and its thermal stability was proved by DSC, TG analysis and thermal treatment at 200 °C. Furthermore, the stability and strength development of cement slurry was evaluated by the comparative consistency method and ultrasonic method, respectively. The results show that DRH-200LG has good high temperature-resistance and retarding performance, presenting favourable influence on the stability and strength development of cement slurry. DRH-200LG shows a good application prospect in the cementation of deep & ultra-deep wells. And it has some guiding significance in the research and innovation of a novel polymer used as oil well cement retarder.

Long-term strength retrogression of silica-enriched oil well cement: A comprehensive multi-approach analysis

2021 ◽  
Vol 144 ◽  
pp. 106424 ◽  
Author(s):  
Xueyu Pang ◽  
Jiankun Qin ◽  
Lijun Sun ◽  
Ge Zhang ◽  
Honglu Wang
Keyword(s):  
Oil Well ◽  
Term Strength ◽  
Oil Well Cement ◽  
Well Cement

Effect of Fly Ash and Slag on the Resistance to H2S Attack of Oil Well Cement

2009 ◽  
Vol 79-82 ◽  
pp. 71-74
Author(s):  
Qi Wang ◽  
Lin Qiao ◽  
Peng Song
Keyword(s):  
Fly Ash ◽  
Compression Strength ◽  
Blended Cement ◽  
Oil Well ◽  
X Ray Diffraction ◽  
X Ray ◽  
Curing Period ◽  
Oil Well Cement ◽  
Xrd Patterns ◽  
Well Cement

In this paper, the resistance to H2S attack of pastes made from slag-fly ash blended cement used in oil well (SFAOW) was studied, in which fly ash (FA) was used at replacement dosages of 30% to 60% by weight of slag. Samples of SCOW and SFAOW pastes were demoulded and cured by immersion in fresh water with 2 Mp H2S insulfflation under 130oC for 15 days. After this curing period, compression strength and permeability of the samples were investigated. The reaction mechanisms of H2S with the paste were carried out through a microstructure study, which included the use of x-ray diffraction (XRD) patterns and scanning electron microscope (SEM). Based on the obtained data in this study, incorporation of FA into SCOW results in the comparable effects in the resistance to H2S attack. When the replacement dosage of slag is about 40%, the paste exhibits the best performance on resistance to H2S attack with compression strength 36.58Mp.

Influence of sulfuric and hydrochloric acid on the resistance of geopolymer cement with nano-silica additive for oil well cement application

2018 ◽  
Vol 9 (5) ◽  
pp. 616-624 ◽  
Author(s):  
Syahrir Ridha ◽  
Afif Izwan Abd Hamid ◽  
Riau Andriana Setiawan ◽  
Ahmad Radzi Shahari
Keyword(s):  
Fly Ash ◽  
Hydrochloric Acid ◽  
Strength Increase ◽  
Oil Well ◽  
Nano Silica ◽  
Content Type ◽  
Oil Well Cement ◽  
Geopolymer Cement ◽  
Well Cement ◽  
Silica Additive

PurposeThe purpose of this paper is to investigate the resistivity of geopolymer cement with nano-silica additive toward acid exposure for oil well cement application.Design/methodology/approachAn experimental study was conducted to assess the acid resistance of fly ash-based geopolymer cement with nano-silica additive at a concentration of 0 and 1 wt.% to understand its effect on the strength and microstructural development. Geopolymer cement of Class C fly ash and API Class G cement were used. The alkaline activator was prepared by mixing the proportion of sodium hydroxide (NaOH) solutions of 8 M and sodium silicate (Na2SiO3) using ratio of 1:2.5 by weight. After casting, the specimens were subjected to elevated curing condition at 3,500 psi and 130°C for 24 h. Durability of cement samples was assessed by immersing them in 15 wt.% of hydrochloric acid and 15 wt.% sulfuric acid for a period of 14 days. Evaluation of its resistance in terms of compressive strength and microstructural behavior were carried out by using ELE ADR 3000 and SEM, respectively.FindingsThe paper shows that geopolymer cement with 1 wt.% addition of nano-silica were highly resistant to sulfuric and hydrochloric acid. The strength increase was contributed by the densification of the microstructure with the addition of nano-silica.Originality/valueThis paper investigates the mechanical property and microstructure behavior of emerging geopolymer cement due to hydrochloric and sulfuric acids exposure. The results provide potential application of fly ash-based geopolymer cement as oil well cementing.

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