الفهرس 
INTRODUCTION & OBJECT OF INVESTIGATION
Classification of oil well cementOnly 14 pages are availabe for public view
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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 areas
of research for the last decades. Oil well cementing is less tolerant of 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
cement in cementing 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 type of admixtures which used in oil well cementing is
superplasticizers (high range water reducers).
This investigation is divided into three sections:
Part I
Part I aims to preparation of the superplasticizers particularly sulfanilic acidcyclohexanone
formaldehyde (CFS), sulfanilic acid-acetone formaldehyde (AFS),
sulfanilic acid-cyclohexanone glyoxylic (CGS), sulfanilic acid-acetone glyoxylic
(AGS) and sulfanilic acid-melamine glyoxylic (MGS), confirm their structures
using FTIR spectra.
Part II
Study the effect of the prepared superplasticizers on the water of
consistency and setting time.
On the basis of the results obtained in this investigation, the conclusions
could be derived:1. Sulfanilic acid-cyclohexanone glyoxylic (CGS) shows the most water reducing
agent at all ratios in comparison with the other cement admixtures
2. Also, increasing the admixture dosages decreases the water of consistency for
all admixtures.
3. The least amount of admixture and the most effective dose is 1% of the
provided CFS which reduces the mixing water from 28% to 21%. This means
that it reduces the water of consistency by 7% or the total reduction in relative
to the original mixing water is 25/0.
4. The initial and final setting times of the cement pastes prepared by
using different dosages such as 0.0, 0.25, 0.50, 0.75 and 1.00/0 as well as
the previously cement admixtures.
5. CFS and AFS acts as somewhat water reducing agent at all dosages. It shows
change in the initial setting time at all dosages in respective to the reduction of
mixing water and the admixed cement paste with the mixing water accelerated
the initial setting.
6. The initial and final setting times of the hardened cement pastes using 0.25.
0.50. 0.75 and l.0% of CGS or AGS or MGS. The results show that the initial
and final setting times are retarded by the addition of these admixtures. As the
dose of admixture increases the initial setting time increases. It can be
concluded that the CGS or AGS or MGS acts as water reducer and retarder.
Part III
Part III study the effect of these admixtures 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 dosages of each type of superplasticizers then molded into
one inch cubic molds. The resulting hardened cement pastes containing 0.10%,
0.25%, 0.50% and 1.00% of prepared superplasticizer by weight of OWC,
respectively. The applied hydration time intervals are 2, 6 hours, 1, 3, 7, 28 and 90days. 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 conclusions could be
derived:
1. The values of the chemically combined water content of the different cement
pastes admixed with different dosages of each prepared superplasticizers are
lower than that of the control sample which is related to the initial W/C ratio.
2. For the all admixtures, as the dosage increases the compressive strength
increases. Evidently, there are some inter-related parameters; namely, W/C ratio,
admixture dosage and degree of hydration that affect the main characteristics of
the fresh and hardened cement pastes.
Part VI
Part VI studies the phase composition and microstructure of the formed
hydrates of the admixed hardened OWC pastes.
The phase composition and microstructure of the formed hydrates for some
selected admixed hardened OWC pastes were identified using X-ray diffraction
(XRD) analysis, differential scanning calorimetry (DSC) and scanning electron
microscope (SEM).
1. DSC 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.
2. A relatively high porosity pastes which are almost similar to that of the neat
OWC paste made without any admixture; which have high water / cement ratio;
the hydration products formed within the available pore system of the cement
paste possess a relatively high crystalline character; these hydrates are initially
formed as nearly amorphous and microcrystalline (CSH and calcium hydroxide) after 1 day of hydration and with a higher degree of crystallinity after 28 days of
hydration with a more denser structure after 90 days of hydration.
Part V
Part V studies the rheological properties of OWC slurries with different
dosages of each prepared superplasticizers at different temperatures. The rheological
properties of OWC slurries are affected by numerous factors including the w/c, size
and shape of cement grains, chemical composition of the cement and relative
distribution of its components at the surface of grains, presence and type of
additives, compatibility between cement and chemical admixtures, mixing and
testing procedures, etc. Moreover, slip at the slurry-shearing surface interface,
particle-particle interactions, chemical reactions, non-homogeneous flow fields, and
human errors can make the rheological experiments difficult to reproduce. However,
during the present tests, every effort was made to minimize experimental error by
strictly following a consistent mixing and testing procedure. The effect of the w/c
and temperature on the rheological properties of OWC slurries incorporating various
chemical admixtures was studied using an advanced rheometer. The coupled effects
of the temperature and dosage of admixture on yield stress, plastic viscosity and
apparent viscosity were studied. Based on the experimental results, the following
conclusions can be drawn:
1. The rheological properties of OWC slurries are highly dependent on
temperature; they generally increased nonlinearly with temperature
increase. This is mainly due to the dependence of the formation of
hydration products on temperature.
2. As expected, the viscosity of OWC slurries decreased significantly with the
increase of the w/c.
3. The rheological properties of OWC slurries depended on the type of
admixture used. AGS and MGS improved fluidity at all test temperatures
and for all dosages used, while slurries incorporating CFS and AFS required more energy to initiate slurry flow since the yield stress increased
at all dosages tested.
4. The admixture dosage had a significant effect on the slurry rheology. At
lower dosages CGS acted as accelerators.