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

Pang, Xueyu; Qin, Jiankun; Sun, Lijun; Zhang, Ge; Wang, Honglu

doi:10.1016/j.cemconres.2021.106424

Cited by 49 publications

(29 citation statements)

References 29 publications

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“…Among these materials, silica flour is the most commonly used anti-strength retrogression agent and it has been proven to be quite effective for thermal recovery wells where the cement was set at a low temperature before high temperature exposure (Jiang et al, 2021;Santiago et al, 2021). However, several of our recent studies (Pang et al, 2021;Liu et al, 2022;Qin et al, 2022) have shown that silica flour is ineffective in preventing long-term strength retrogression at deep well conditions where the cement was set and cured both at 200 °C. While it is clear that the long-term strength retrogression is accompanied by cement microstructure coarsening, some inconsistent conclusions have been drawn with regard to what caused microstructure coarsening, primarily due to uncertainties in X-ray diffraction analysis.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of long-term strength retrogression of silica-enriched Portland cement assessed by quantitative X-ray diffraction analysis

Qin

Pang

et al. 2022

Front. Mater.

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In order to clarify on the driving force of cement long-term strength retrogression, a comprehensive quantitative X-ray diffraction (XRD) analysis were conducted on silica-enriched (60%–80% by weight of cement) cement samples set and cured under the condition of 200°C and 50 MPa with a maximum duration of 180 days. The phase content evolution with time was determined by three different methods on the average of three specimens: the external standard method; the partial or no known crystal structure (PONKCS) method; and the hybrid method. Although the specific phase content estimated by different methods varied slightly, the overall trend of change of all phases were similar. The phase transformation in set cement at high temperature condition is dependent on the slurry composition. In silica-deficient system, tobermorite and amorphous C-S-H were transformed to xonotlite; while in silica-sufficient system, tobermorite and amorphous C-S-H were transformed to gyrolite. These phase transformations involve gradual structural changes of cement hydration products, which may be the driving force of long-term strength retrogression. However, such structural changes can only be detected by XRD once the transformation is complete.

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Section: Introductionmentioning

confidence: 99%

Mechanism of long-term strength retrogression of silica-enriched Portland cement assessed by quantitative X-ray diffraction analysis

Qin

Pang

et al. 2022

Front. Mater.

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“…However, at 150°C, 250°C and 340°C, the porosity increases with the increase of curing time. This is due to long-term curing of SSE cement at high temperatures leading to the dehydration of hydration products [ 6 ], and thereby enlarging the void space in SSE cement. At 380°C, an obvious rise of porosity can be observed in figure 9 .…”

Section: Resultsmentioning

confidence: 99%

“…As also confirmed by Pang et al . [ 6 ], long-term curing (up to 142 days) of silica-enriched cement experiences deterioration in mechanical and physical performance, such as permeability and compressive strength. Wang et al .…”

Section: Discussionmentioning

confidence: 99%

Effects of microstructure on compressive strength of silica sand-enhanced oil well cement at a wide temperature range

Chen

Du²,

Zhou³

et al. 2022

R. Soc. open sci.

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The influence of microstructure of silica-enhanced cement on the mechanical performance of cement is difficult to describe. In this study, we used the scanning electron microscope and image processing method to investigate the relationship between the complicity of cement microstructure and compressive strength under various temperatures and curing times. Fractal dimension was applied to describe the complicity of silica-enhanced cement. The relationships among compressive strength, fractal dimension, temperature, curing time and pore structure of cement were identified. The results show that curing time directly controls the complicity of microstructure of silica-enhanced cement and compressive strength by altering the pore orientation and macropore ratio in silica-enhanced cement. The curing temperature affects the complicity of cement microstructure and compressive strength indirectly by changing the ratio of micropore and small pore. The fractal dimension of silica-enhanced cement shows good correlation with compressive strength. Pore size distribution is the most important factor that influences the complicity of cement matrix and compressive strength of silica-enhanced cement. When building up the macroscopic mechanical performance model of silica-enhanced cement, we should consider the influence of pore size distribution in cement under different curing temperatures and times on the complicity of cement microstructure.

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“…During well cementing, oil well cement used to provide well integrity is susceptible to formation stress, periodic external pressure changes, and the difference in elasticity between the cement sheath and casing during the production of wells. [1][2][3][4] These stresses and pressures may produce unbalanced forces in the cement stone, causing brittle fracture or the formation of micro-annulus and micro-cracks. 5 The destruction of the downhole cement sheath seriously affects the productivity and production safety of wells.…”

Section: Introductionmentioning

confidence: 99%

Effect of core–shell nanocomposites on the mechanical properties and rheological behaviors of cement pastes

Wang

Tan

et al. 2022

RSC Adv.

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

Cited by 49 publications

References 29 publications

Mechanism of long-term strength retrogression of silica-enriched Portland cement assessed by quantitative X-ray diffraction analysis

Mechanism of long-term strength retrogression of silica-enriched Portland cement assessed by quantitative X-ray diffraction analysis

Effects of microstructure on compressive strength of silica sand-enhanced oil well cement at a wide temperature range

Effect of core–shell nanocomposites on the mechanical properties and rheological behaviors of cement pastes

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