الفهرس 
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Abstract
Oil-well cementing is considered as one of the most critical operations in petroleum and gas industry. Therefore, it becomes one of the most interesting area of research for the last decades. Oil well cementing is less tolerant to errors than conventional cementing works. If the cement does not provide a good seal, gas or liquid fluids can migrate to the surface and lead to work accidents or environmental problems. So, the full understanding of interfacial phenomena behind oil well cement procedures has scientific, economic and environmental importance.
Chemical admixtures have become one of the essential components of concrete in concrete technology in recent years. Various chemical admixtures different in composition have been offered to the users today in response to the needs of the construction market.
The major types of admixtures which used in concretes are: plasticizers (normal water reducers), superplasticizers (high range water reducers), retarders, retarding water reducers, and air entraining admixtures (AEA).
This investigation is divided into three sections:
Part I
Part I aims to prepare a new organic aliphatic compound namely: acetone formaldehyde sulfonate (AFS), confirm its structure using FTIR spectra and elemental analysis estimation of (carbon, hydrogen, oxygen and sulfur) and study the effect of this admixture on the physico-chemical and mechanical characteristics of hardened pastes made of OWC.
The pastes were prepared using the values of standard water of consistency (W/C ratio) with various additions of AFS then molded into one inch cubic molds. The resulting hardened cement pastes are designated as AI, AII, AIII and AIV for pastes containing 0.10, 0.25, 0.50 and 1.00(%) AFS by weight of OWC, respectively. The applied hydration time intervals are 0.5, 1, 2, 6 hours, 1, 3, 7 and 28 days. At each time of hydration the hydrated pastes were tested for compressive strength, while the other physico-chemical properties were investigated using the ground dried samples.
On the basis of the results obtained in this investigation, the following conclusions could be derived:
1. The OWC hardened pastes admixed by different additions of AFS (Mixes AI - AIV) showed nearly the same trend as in case of neat OWC paste (Mix A0), with a notable lower values of compressive strength values of AFS admixed OWC pastes especially during the early stages of hydration (up to 7 days) as compared to the neat OWC paste (blank); but they showed comparable strength values and/or higher values after 28 days compared to the blank. Also, with increasing additions of AFS, the decrease in the values of compressive strength increases up to 7 days and the reverse occur after 28 days of hydration. The previous results can be attributed to the retardation effect of the AFS admixture.
2. The variations of the values of combined water content (Wn. ;%) with age of hydration are in agreement with the variations in values of compressive strength.
3. The free lime contents (CaO, %) obtained for all the admixed OWC (Mix AI-AIV) hardened pastes are lower than those of neat OWC paste (Mix A0); this is due to the retardation effect of AFS admixture.
4. Rheological measurement indicated that the mini-slump values of OWC pastes admixed with different doses of AFS were increasing with increasing AFS doses; this is mainly increase due to the increase in the fluidity of these cement pastes.
5. DTGA thermograms and XRD difractograms obtained for the tested pastes indicate the formation of: nearly amorphous calcium silicate hydrates (mainly as CSH-I and CSH-II), calcium sulphoaluminate hydrates (ettringite and monosulphate hydrates), CH and CaCO3.
Part II
Part II aims to prepare a new organic aliphatic compound namely: cyclohexanone glyoxylate (CG), confirm its structure using FTIR spectra and elemental analysis (carbon, hydrogen, oxygen, and sulfur) and study the effect of this admixture on physico-chemical and mechanical characteristics of hardened OWC cement pastes.
The pastes were prepared using the values of standard water of consistency (W/C ratio) with various additions of CG then molded into one inch cubic molds. The resulting hardened cement pastes are designated as BI, BII, BIII and BIV for pastes containing 0.1%, 0.25%, 0.5% and 1.0 % CG by weight of OWC, respectively. The applied hydration time intervals are 0.5, 1, 2, 6 hours, 1, 3, 7 and 28 days. After 1, 3, 7 and 28 days of hydration the hydrated pastes were tested for compressive strength, while the other physico-chemical properties were investigated using the ground dried samples after each time interval.
On the basis of the results obtained in this investigation, the following conclusions could be derived:
1. The compressive strength values obtained for the hardened OWC pastes admixed by different additions of CG (Mixes BI-BIV) showed nearly the same trend as in case of blank (Mix A0); but with a notable lower values of strength especially during the early stages of hydration (up to 7 days) as compared to the blank (neat OWC). After 7 days the results showed a comparable and / or higher strength value, except the specimens made from Mix BI which showed slight higher values of compressive strength than those of the blank at 3 and 7 days and showed the highest compressive strength value among all tested specimens after 28 days. Also, as the %wt. additions of CG to OWC increase the decrease in the values of compressive strength increase.
2. The variations of the values combined water content (Wn, %) with age of hydration are in agreement with the variations in values of compressive strength.
3. The free lime contents (CaO, %) obtained for all of the admixed OWC hardened pastes (Mix BI-BIV) are lower than those of neat OWC paste (Mix A0).
4. Rheological measurement indicated that the mini-slump values of cement pastes admixed with different doses of CG increase with increasing CG doses; this is mainly due to increase the fluidity of these cement pastes.
5. DTGA thermograms and XRD difractograms obtained for the hardened pastes indicate the formation of: nearly amorphous calcium silicate hydrates (mainly as CSH-I and CSH-II), calcium sulphoaluminate hydrates (ettringite and monosulphate hydrates), calcium hydroxide (CH) and CaCO3.
Part III
Part III aims to prepare a new organic aliphatic compound namely: acetone glyoxylate (AG), confirm its structure using FTIR spectra and elemental analysis (carbon, hydrogen, oxygen and sulfur) and study the effect of this admixture on physico-chemical and mechanical characteristics of hardened pastes made of OWC.
The pastes were prepared using the values of standard water of consistency (W/C ratio) with various additions of AG then molded into one inch cubic molds. The resulting hardened cement pastes are designated as CI, CII, CIII and CIV for the pastes containing 0.1%, 0.25%, 0.5% and 1.0 % AG by weight of OWC, respectively. The applied hydration time intervals are 0.5, 1, 2, 6 hours, 1, 3, 7 and 28 days. After 1, 3, 7 and 28 days of hydration the hydrated pastes were tested for compressive strength, while the other physico-chemical properties were investigated using the ground dried samples at each time interval.
On the basis of the results obtained in this investigation, the following conclusions could be derived:
1. The hardened OWC pastes admixed with different additions of AG (Mixes CI-CIV) showed nearly the same trend as in case of the blank (Mix A0); but with a notable lower values of strength especially during the early stages of hydration (up to 7 days) as compared to the blank; but they showed comparable strength values to the blank after 28 days. Also the results obtained indicated that; as the % wt. additions of AG increase, the values of compressive strength showed more lower values up to 28 days of hydration. So that specimens made from Mix CI (0.25% addition of AG) possesses the highest strength values as compared to other mixes during all ages of hydration.
2. The variations in the values combined water content (Wn, %) with age of hydration are in agreement with the variations in values of compressive strength.
3. The free lime contents (CaO, %) obtained for all the admixed OWC (Mix CI-CIV) hardened pastes are lower than those of neat OWC paste (Mix A0).
4. Rheological measurement indicated that the mini-slump values of cement pastes admixed with different doses of AG increase with increasing AG doses; this is mainly due to the increase in the fluidity of these cement pastes.
5. DTGA thermograms and XRD difractograms obtained for the hardened pastes indicate the formation of: nearly amorphous calcium silicate hydrates (mainly as CSH-I and CSH-II), calcium sulphoaluminate hydrates (ettringite and monosulphate hydrates), calcium hydroxide (CH) and CaCO3.