By Weight Of Cement Research Articles

Enhancing the properties of high-density oil well cement with Qusaiba kaolinite

High-density cement slurries used in oil well cementing often face challenges such as particle settling, poor rheological properties, permeability, and compressive strength degradation, which can compromise zonal isolation and well integrity. This study focuses on using kaolinite, a clay mineral, as an additive due to its potential to improve the performance of high-density cement by modifying key properties. Several concentrations of kaolinite were examined to evaluate their influence on several cement properties such as rheology, thickening time, permeability, porosity, and compressive strength. Additionally, it assesses the impact of kaolinite on cement sheath solids settling using both conventional methods and nuclear magnetic resonance (NMR). The results revealed that an optimal concentration of 1% kaolinite by weight of cement (BWOC) significantly reduced particle settling by 74.4%, enhanced compressive strength by 13%, and lowered permeability and porosity by 74% and 7%, respectively. Additionally, kaolinite improved rheological properties by an 8.4% reduction in plastic viscosity, a 19.4% increase in yield point, and a 30% increase in gel strength. Kaolinite also acted as a retarder, increasing thickening time. These improvements contribute to better cement sheath integrity and wellbore stability, highlighting kaolinite’s potential as an effective additive for high-density cement.

Synthetic Clay Application to Reduce the Segregation of Barite-Based Oil-Well Cement.

In the oil and gas industry, cement segregation is a significant concern that can have disastrous consequences, such as the failure of cement. The change of hardened cement's properties is observed, resulting in a decrease in its strength and an increase in its permeability. Therefore, providing some solutions to prevent this is crucial. The objective of this study is to assess the efficacy of synthetic clay in mitigating the problem of segregation in cement having barite. Six concentrations of synthetic clay were used to prepare six heavy-weighted cement samples with a high density of 18 lb/gal using the barite weighting material. The approaches of density distribution and nuclear magnetic resonance (NMR) were employed to characterize the heterogeneity in the hardened cement samples with the aim of identifying the potential of cement segregation. Then, the optimum concentration of the synthetic clay was selected and its effects on the rheological, strength, petrophysical, and elastic properties were evaluated and compared with the properties of the base cement (without synthetic clay). The results showed that 0.4% by weight of cement (BWOC) synthetic clay was the optimum concentration, which yielded the minimum cement segregation as represented by a 61% reduction in the density variation compared to the control specimen. The results obtained from the NMR technique validated the findings of the density distribution method, indicating that the porosity distribution of the synthetic clay cement with a concentration of 0.4% BWOC exhibited uniformity across its top, middle, and bottom sections, with a slight deviation window, while the porosity distribution of the control cement specimen displayed noticeable variation. Moreover, the synthetic clay had better properties than the control cement specimen. For example, the rheological properties were improved as represented by a 22% reduction in plastic viscosity and 42 and 11% increase in the yield point and gel strength, respectively. Compared to the base cement, the compressive and tensile strength were increased by 39 and 43%. The synthetic clay decreased the permeability and porosity by 73 and 24%, respectively. The synthetic clay enhanced the elastic properties as represented by a 1.5% reduction in Young's modulus and a 1.3% increase in Poisson's ratio compared to the base cement sample.

Performance Assessment of Bismuth Ferrite Nanoparticles in Enhancing Oilwell Cement Properties: Implications for Sustainable Construction

Summary Oilwell cement ensures wellbore stability and isolates zones while bearing casing load and formation pressure. Its properties, crucial in extreme downhole conditions, include compressive strength, fluid loss resistance, and durability. In the present work, bismuth ferrite nanoparticles (BFO NPs) were synthesized using the sol-gel method and used as an additive in oilwell cement. The synthesized BFO NPs were characterized using Fourier transform infrared (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), and dynamic light scattering (DLS) techniques to analyze the functional groups, crystalline structure, morphological features, and hydrodynamic size distribution. Tests at 70°C and 2,000 psi revealed that 1% by weight of cement (BWOC) BFO NPs increased compressive strength by ~136% and reduced fluid loss to ~64% compared with base cement. It can be conjectured that the exposed facets of BFO NPs containing oxygen act as nucleating sites that promote the ordering of the silicate tetrahedra, thereby increasing the strength and crystallinity and reducing the water loss. The experimental results confirm that the BFO NPs can improve the properties of oilwell cement slurry at high-pressure, high-temperature (HPHT) conditions. This research underscores the potential of BFO NPs as sustainable additives for optimizing oilwell cement performance under challenging HPHT conditions, paving the way for advancements in sustainable construction practices.

An Experimental Study to Demonstrate the Effect of Alumina Nanoparticles and Synthetic Fibers on Oil Well Cement Class G

In the drilling and production operations, the effectiveness of cementing jobs is crucial for efficient progress. The compressive strength of oil well cement is a key characteristic that reflects its ability to withstand forceful conditions over time. This study evaluates and improves the compressive strength and thickening time of Iraqi oil well cement class G from Babylon cement factory using two types of additives (Nano Alumina and Synthetic Fiber) to comply with the American Petroleum Institute (API) specifications. The additives were used in different proportions, and a set of samples was prepared under different conditions. Compressive strength and thickening time measurements were taken under different conditions. The amounts of Nano Alumina (0.5%, 1%, and 1.5% by weight of cement (BWOC)) were selected with synthetic fiber (0.5 g, 1 g, and 1.5 g, respectively). The results show a significant improvement in compressive strength, with all values meeting the API requirements, and a decrease in the thickening time of Iraqi oil well cement, depending on the proportions of additives. The most significant improvement in compressive strength was achieved in the sample containing 1.5% Nano Alumina by weight of cement (BWOC) and 1.5 g Synthetic Fiber (Barolift), where the compressive strength increased by 40.7% and 33.8% at a temperature of 38 °C and 60 °C, respectively, while the thickening time decreased by 26.53% at this ratio of additives. The results demonstrate the feasibility of using these additives to enhance the performance of Iraqi oil well cement, expanding its potential application in Iraqi oil fields.

Minimizing the particles settling of ilmenite weighted oil well cement using laponite

Cementing operations are fundamental undertakings during the drilling and completion of oil and gas wells, ensuring zonal isolation and structural stability within the wellbore. Ilmenite serves as a dominant weighting material for high-density cement. However, challenges associated with its particle settling have arisen, reporting the potential for various complications within the cement sheath. In this context, the present study used laponite, a synthetic layered clay, to address the issue of particles settling in ilmenite-weighted oil well cement under high pressure and high-temperature curing conditions. The investigation extended to comprehensively assessing the consequences of incorporating laponite on the cement's rheological, mechanical, and petrophysical properties. Varied concentrations of laponite were employed and compared against the base cement, devoid of laponite. A total of six high-density cement samples of 18 ppg at different concentrations of laponite were prepared under a high pressure of 3000 psi and a high temperature of 294 °F. Findings from this work revealed that an optimal laponite concentration of 0.3% by weight of cement (BWOC) appeared to be the most effective. Adding laponite to the cement led to an impressive 83% reduction in particle settling within ilmenite-weighted cement. This deduction was confirmed through the direct density variation method and NMR measurements. Moreover, the inclusion of laponite yielded favorable outcomes in the rheological aspects of oil well cement. Laponite-based cement showed a 40% reduction in plastic viscosity and a 31.5% and 14.5% increase in yield point and gel strength, respectively, compared to the base cement formulation. Mechanically, laponite had a tangible positive impact, evidenced by a 95% and 131% increase in compressive and tensile strengths, respectively and a 16% reduction in Young's modulus, all relative to the base cement sample. Significantly, laponite's role extended to pore space optimization, leading to a decline in cement porosity by 2% and a 25% reduction in permeability.

Experimental Investigation to Enhance Oil Well Cement Compressive Strength by Using Nano Silica and Synthetic Fiber

The cementing process is one of the main and vital elements in the drilling and completion of oil and gas wells. Cement slurry design plays an essential role in cementing operations. Compressive strength, which represents a material's ability to sustain forceful conditions over time, is an essential property of oil well cement. This study provides an experimental investigation on the impact of coupled synthetic fiber and Nano Silica (nano-SiO2) on improving the compressive strength of Iraqi oil well cement class G. In addition, the results were compared to those of a previous study that utilized Nano Silica alone in conjunction with Iraqi oil well cement. The results indicated that the Iraqi oil well cement class G, after special additions, conforms to the specifications of the American Petroleum Institute (API). Results showed that adding synthetic fiber and Nano-Silica together significantly increased the compressive strength of Iraqi class G cement slurry cured at different conditions. Samples curing was done at 38°C and 60°C for 8 hours. The results indicated that the cement system with 1.5% by weight of cement (BWOC) of Nano-Silica and 1.5 gm of Synthetic Fiber increased the compressive strength by 50.38 and 39.92% at 38°C and 60°C, respectively. Through comparison with previous studies, it was found that the amounts of Nano Silica added to cement can be reduced by a large percentage when synthetic fibers are added with it, thus reducing the cost of using nanomaterials.

Expandable Geopolymers Improve Zonal Isolation and Plugging

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 212493, “Expandable Geopolymers for Improved Zonal Isolation and Plugging,” by Foster D. Gomado, SPE, Mahmoud Khalifeh, SPE, and Jan A. Aasen, SPE, University of Stavanger. The paper has not been peer reviewed. _ The sealability performance of an expanding geopolymer (E-GP) is compared with that of an expansive commercial cement (EC) with regard to shear bond strength (SBS) and hydraulic bond strength (HBS) at curing conditions of 25°C and 34.5 bar. A neat Class G (NG) cement and a neat geopolymer (N-GP) were characterized alongside corresponding expansive versions. The effect of these expansive agents on cement and geopolymers was evaluated in terms of linear expansion using the annular ring test. The complete paper reveals that geopolymers can be deployed as an alternative to Portland cement upon optimization. Geopolymer Characteristics and Use In recent years, geopolymers have been receiving attention as a viable and environmentally friendly alternative for zonal isolation and plugging and abandonment (P&A) operations because of their robust features such as higher strength, lower permeability, and durability in high-pressure/high-temperature conditions. Geopolymers can be described as binders formed by a chemical reaction between aluminosilicate materials and alkali hydroxide or soluble silicates. In this study, cement/casing bonding properties are the primary focus. Greener options for cementing, zonal isolation, and P&A must meet acceptable criteria before mass adoption. Geopolymers, like Portland cement, experience shrinkage to some extent. To improve cement bonding, expansive agents are regarded as relevant additives, correlating volume changes to bonding properties, mostly SBS. In the case of geopolymers, few studies have been directed toward the study of volumetric changes with and without expansive additives. The current literature for geopolymers lacks correlation between the performance of expansive agents on geopolymers in terms of HBS, SBS, and load-to-displacement profile. Thus, the authors explored the effect of expansive agents on SBS and accompanying interfacial friction and hydraulic sealability for both NG and EC, as well as neat geopolymers and expansive versions at equal conditions. Experimental Procedures NG cement was used as a reference because it is the most widely used cement in the Norwegian North Sea. The EC was made by the addition of a commercially available expansive agent [made of a blend of calcium oxide (CaO) and quartz] to NG at a concentration of 5% by weight of cement (BWOC). The geopolymer deployed in this study was synthesized in house. The E-GP was synthesized by the addition of a calcium salt in a concentration of 1.1% of the solid precursors. The complete paper details slurry preparation and the methodology for linear-expansion (shrinkage) tests, SBS/bond slip tests, and HBS tests.

Analysis of the Impact of Vermiculite on Hematite-Based Cement Systems.

Heavyweight oil-well cement systems are designed for isolating intervals and supporting the casing at deeper depths where high temperatures and pressures are encountered. The cement slurry should have adequate rheology to ensure efficient placement. Additionally, the hardened cement sheath should be homogeneous with lower porosity and permeability, higher strength, and sufficient flexibility. The effect of vermiculite on hematite-based cement samples has been investigated. The methodology and testing were based on the American Petroleum Institute standards and other recognized recommendations. Fluid properties were characterized by their rheology, while petrophysical and mechanical properties were used to analyze the properties of hardened cement specimens. The vermiculite was used in concentrations of 0.25, 0.5, 1, and 2% by weight of cement (BWOC). The slurries were cured at 3000 psi and 292 °F in cubic and cylindrical molds for 24 h. The results indicate that using 1% BWOC of vermiculite yields the best cement properties. It minimizes the settling of hematite particles to a very low value compared to the base cement as shown by the method of density variation and confirmed by nuclear magnetic resonance. Compared to the base cement slurry, the slurry of 1% BWOC of vermiculite has desirable rheology in terms of plastic viscosity and gel strength. The incorporation of 1% BWOC improves the strength of the cement sheath by 50.7% for the compressive strength and 65% for the tensile strength. Adding 1% vermiculite reduces the permeability and porosity of the cement by 45.8 and 43.5% compared to the control cement. In addition, the 0.7% vermiculite cement is more flexible than the control cement in terms of the elastic properties represented by lower Young's modulus (a reduction of 33%) and higher Poisson's ratio (an increase of 2%).

Cement Slurry Design for High-Pressure, High-Temperature Wellbores Using Polymer Nanocomposite: A Laboratory Scale Study Based on the Compressive Strength and Fluid Loss

For the successful cementing operation of petroleum wells, the design of cement slurry plays a crucial role. Cement slurry must address the requirements of higher compressive strength; lower fluid loss; durability; and high-pressure, high-temperature (HPHT) challenges. A large number of chemical additives in cement slurry affects the required rheological properties; therefore, the development of multifunctional additives is desirable. In the present study, this problem has been addressed with the use of a single polymeric nanocomposite additive to address multiple requirements. A novel tetrapolymer nanocomposite (TPN) was synthesized in the laboratory by in situ polymerization in the presence of zinc oxide nanoparticles. Four monomers, namely acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, vinyl phosphonic acid, and N-[3-(dimethylamino)propyl] methacrylamide, were selected for the in situ polymerization reaction. The synthesized product was characterized using 1H NMR, FTIR, and TGA techniques. Laboratory-synthesized TPN was mixed in varying concentrations in the cement slurry as an additive. The performance of the enhanced cement slurry was then evaluated by performing compressive strength analysis and a filtration test using an ultrasonic cement analyzer and an HPHT filter press, respectively. These experimental analyses show that the addition of the TPN improved the compressive strength of the cement slurry and, at the same time, abbreviated the fluid loss, which is desired for efficient cementing operation. With the addition of 1.0% by weight of cement (BWOC) of TPN, the compressive strength increased by ∼136% compared with base cement. Additionally, this small dosage also reduced HPHT fluid loss by ∼67%. This experimental investigation shows that the novel TPN additive is capable of improving the efficacy of oil-well cement slurry at high-temperature conditions without compromising on thickening time because the additive also improved the waiting-on-cement time for HPHT conditions.

Optimization of Cement–Rubber Composites for Eco-Sustainable Well Completion: Rheological, Mechanical, Petrophysical, and Creep Properties

To ensure well integrity, wellbore must be strongly cased using durable cement slurries with essential additives during downhole completion. The rubber materials that come from industrial waste are becoming extremely encouraged in the use as an additive in preparing cement slurries due to their growing environmental footprint. However, the proper design of cement slurry strongly depends on its rheological, mechanical, petrophysical, and creep properties, which can be altered by changing additives. This study aimed to examine the cement properties under alteration in different chemical admixtures to create efficient binding properties, and to estimate the optimum cement–rubber slurry composition for eco-sustainable completion. Three cement samples with different mesh sizes of the crumb rubber particles were prepared. This study examined the variation in rheological behaviors, elastic and failure characteristics, permeability, and creep behavior of the cement–rubber composites for petroleum well construction. The experimental study showed that the addition of 15% or more crumb rubber to the cement resulted in very thick slurries. Moreover, it was shown that the addition of crumb rubber with various particle sizes to the cement reduced the strength by more than 50%, especially for a higher amount of rubber added. It was also revealed that the addition of a superplasticizer resulted in an 11% increase in compressive strength. The results showed that cement–crumb-rubber composites with 12% by weight of cement (BWOC) represented the optimum composite, and considerably improved the properties of the cement slurry. Water-permeability tests indicated the addition of 12% BWOC with 200-mesh crumb rubber decreased the permeability by nearly 64% compared to the base cement. Creep tests at five different stress levels illustrated that the neat cement was brittle and did not experience strain recovery at all stress levels. Cement slurries with the largest rubber-particle size were elastic and demonstrated the highest amount of strain recovery. Finally, a relationship was established between the permeability, average strain, and mesh size of the rubber particles, which offered the strain recovery, satisfied the zonal isolation, and consequently reduced the microannulus problem to ensure the cement’s integrity.

The Use of Graphite to Improve the Stability of Saudi Class G Oil-Well Cement against the Carbonation Process.

Oil-well cement physical characteristics considerably change after being carbonated by a CO2-rich solution. In this study, the influence of graphite particles in the characteristics of oil-well cement reacted with a CO2-rich solution at 130 °C and 10 MPa for 10 days was studied. After 10 days of carbonation, incorporating 0.2% by weight of cement (BWOC) of graphite into the cement slurry decreased the carbonation depth by 29.8% as confirmed by the direct measurement and the micro-computerized tomography scan technique. The addition of 0.2% BWOC of graphite also reduced the cement matrix permeability by 31.4% and increased its compressive strength by 16.4% and tensile strength by 23.8% compared to the sample without graphite. The decrease in the cement matrix portlandite concentration and permeability of the samples prepared with graphite contributed to promote the cement matrix carbonation resistance. The microscopic images also proved that the incorporation of graphite delayed the leaching of calcium carbonate, and this is also attributed to decreasing the cement strength deterioration.

IMPROVING MECHANICAL PROPERTIES OF OIL WELL CEMENT USING POLYPROPYLENE FIBERS AND EVALUATING A NEW LABORATORY METHOD FOR MEASURING THE CASING CEMENT BONDING STRENGTH

The main objective of this study is to enhance the poor performance of oil well cement in terms of mechanical properties by using pure polypropylene fibers. Polypropylene fibers were added in increasing concentrations from 0 to 0.1%, 0.3%, 0.5%, 0.7%, and 0.9% by weight of cement (BWOC). Rheological parameters, density, fluid loss, permeability, porosity, compressive strength, tensile strength, and flexural strength were all tested. A new method for measuring the tensile strength of cement samples in the presence of a casing is also evaluated in this research. In addition, the interfacial bonding shear strength, which represents the strength of cement adhesion to the casing, was measured using a new laboratory procedure. The influence of adding polypropylene fibers on rheology, density, and fluid loss can be ignored, according to the results of the experiments. The permeability and porosity of cement samples increased as the proportion of polypropylene fibers increased, according to the findings. Further, an increase in polypropylene fibers concentration up to 0.3% BWOC led to improving the mechanical properties at different curing times. The bonding strength of the casing cement interface improved with increasing polypropylene fibers concentration up to 0.5% BWOC.

Physio-chemical interaction of Ethylene-Vinyl Acetate copolymer on bonding ability in the cementing material used for oil and gas well

Effective bond of cement sheath to casing or formation depends on higher tensile strength and lower young's modulus which are a measure of its ability to withstand deformation under load without parting. This work utilized Ethylene Vinyl Acetate (EVA) redispersible polymer powder as additive in the class G cement to characterize bonding ability. Tensile strength was measured for samples cured at 90 °C for 3 days, whereas compressive strength was measured for samples cured at 120 °C for 1 day and 3 days under atmospheric pressure. The results showed that, with the addition of beyond 10% by weight of cement (BWOC) of polymer, not only tensile strength was improved, but also reduced young's modulus. Addition of EVA additive beyond 10% BWOC showed significant benefit of flexibility in the cement system. FTIR (Fourier Transform Infrared Spectroscopy) indicated that presence of high VA (Vinyl Acetate) has no effect on polymerization of Silicates, which shows it does not hider in the formation of C–S–H phase. Intensity of chemical bond augmented with longer curing time and increased polymer content, as seen in O–H stretching vibration at 3434 cm−1 and from Carboxylate anion at 1571 cm−1 to confirm on hydrolysis. Mercury Intrusion porosimeter (MIP) showed significant reduction in fraction of mesopore sizes within the cement matrix, with the polymer addition.

Research on Fresh and Hardened Sealing Slurries with the Addition of Magnesium Regarding Thermal Conductivity for Energy Piles and Borehole Heat Exchangers

Currently, renewable energy is increasingly important in the energy sector. One of the so-called renewable energy sources is geothermal energy. The most popular solution implemented by both small and large customers is the consumption of low-temperature geothermal energy using borehole heat exchanger (BHE) systems assisted by geothermal heat pumps. Such an installation can operate regardless of geological conditions, which makes it extremely universal. Borehole heat exchangers are the most important elements of this system, as their design determines the efficiency of the entire heating or heating-and-cooling system. Filling/sealing slurry is amongst the crucial structural elements. In borehole exchangers, reaching the highest possible thermal conductivity of the cement slurry endeavors to improve heat transfer between the rock mass and the heat carrier. The article presents a proposed design for such a sealing slurry. Powdered magnesium was used as an additive to the cement. The approximate cost of powdered magnesium is PLN 70–90 per kg (EUR 15–20/kg). Six different slurry formulations were tested. Magnesium flakes were used in designs A, B, C, and magnesium shavings in D, E and F. The samples differed in the powdered magnesium content BWOC (by weight of cement). The parameters of fresh and hardened sealing slurries were tested, focusing mainly on the thermal conductivity parameter. The highest thermal conductivity values were obtained in design C with the 45% addition of magnesium flakes BWOC.

The Influence of Glass Fiber and Milled Glass Fiber on the Performance of Iraqi Oil Well Cement

The reinforced fiberglass in cement slurry reflects the effect on its properties compared to usual additives. Fiberglass is typically used in cement slurry design for one or another of the following goals: (Earth earthquake, bearing storage, and with differential stresses, to enhance cement durability and increase its compressive strength). The main goal is to use glass fiber and ground fiberglass to improve the tensile strength and moderate compressive strength significantly. On the other hand, the use of glass fibers led to a slight increase in the value of thickening time, which is a desirable effect. Eleven glass fiber samples and milled glass fiber were used to show these materials' effect on Iraqi cement with (0.125, 0.25, 0.5, 0.75, 1, and 2) % of cement weight. Those tests used to study cement slurry‟s following properties were compressive strength, thickening time, rheology properties of free water, filtering, and density. These evaluations showed that slurries with less than 1% fiber content gave a higher compressive strength than a sample containing more than 1% glass fiber. However, the slurry mixed with equal or less than 1% milled glass fiber is higher compressive than the sample mixed with more than 1% milled glass fiber. So the optimal concentration for glass fiber is less than 1% by weight of cement (BWOC); either for milled glass fiber, it is less or equal to 1% BWOC. Both materials contributed to increasing the compressive strength of the cement. However, attention must be paid to the idealThis work is licensed under a Creative Commons Attribution 4.0 International License.
 concentration that should be added during the cement slurry preparation because if we use these two materials carelessly for the ideal concentration, this leads to the collapse and bombardment of the resistance of the cement rock. In other words, the collapse of cement resistance and causing problems during the cementing process.

Optimization of wellbore cement sheath resilience using nano and microscale reinforcement: A statistical approach using design of experiments

In this study, silica (SiO2) nanoparticles were deposited on the surfaces of micro-synthetic polypropylene (PP) fibers through the sol-gel process and combined with Alumina Nanofibers (ANF's) to enhance the cement composite mechanical properties. Cement samples were cured at 82.2 °C with 20.68 MPa for 24 h to emulate wellbore conditions. Mechanical properties were experimentally tested and modeled through the design of experiments (DOE). Treated PP fibers did not contribute to the ultimate strength mainly due to their inability to resist stresses before cracks appear. Ultimate modulus of elasticity (MOE) and Poisson's Ratio were synergistically improved on the nano and microscale levels. This is due to cement samples remaining in the elastic region and the flexibilities of the fibers. 0.15% ANF and 0.09% PP fibers by weight of cement (BWOC) were considered the optimum values after performing the multi-objective optimization analysis. Derived models were statistically significant and useful for predictions.

The Use of the Granite Waste Material as an Alternative for Silica Flour in Oil-Well Cementing.

Silica flour is one of the most commonly used material in cementing oil wells at high-temperature conditions of above 230 °F to prevent the deterioration in the strength of the cement. In this study, replacement of the silica flour with the granite waste material at which an inexpensive and readily available material in cementing oil-wells is evaluated. Four cement samples with various amounts of silica flour and granite powder were prepared in this work. The effect of including the granite waste instead of silica flour in the cement elastic, failure, and petrophysical properties after curing the samples at 292 °F and 3000 psi was examined. The results revealed that replacement of the silica flour with 40% by weight of cement (BWOC) optimized the cement performance and confirmed that this concentration of granite could be used as an alternative to the silica flour in oil-well cementing. This concertation of granite slightly improved the elastic properties of the cement. It also improved the cement compressive and tensile strengths by 5.7 and 39.3%, respectively, compared to when silica flour is used. Replacement of the silica flour with 40% BWOC of granite waste also reduced the cement permeability by 64.7% and porosity by 17.9%.

Improving the mechanical characteristics of well cement using botryoid hybrid nano-carbon materials with proper dispersion

As a key barrier to ensure zonal isolation and wellbore integrity, well cement is required to have good flexibility and higher strength to withstand increasingly hostile downhole conditions. Nano-carbon materials are promising fillers to endow significant improvement in mechanical properties, anti-crack abilities, and durability of well cement. In this study, botryoid hybrid nano-carbon materials (BHNCMs) are introduced into wellbore cement at different concentrations (0.5% to 3% by weight of cement) for the first to formulate more flexible wellbore cement composites. The density, rheological properties, thickening time, fluid loss, and free fluid of the slurries of neat cement and cement composites were measured to evaluate the impact of the addition of BHNCMs on the workabilities of neat cement slurry. The triaxial compressive strength tests, which simulate more realistic downhole stress conditions, were performed to investigate the mechanical properties of hardened BHNCM cement composites. The results show that BHNCMs only need a simple preparation method to be effectively dispersed due to their self-assembled botryoid structure, which help manage the problem of agglomeration of nanocarbon materials. The addition of BHNCMs significantly improves the flexibility of oil well cement and enhances its strength. The optimal concentration of BHNCMs for successful improvement of well cement properties is found to be 1% by weight of cement (BWOC). At the optimum concentration, the compressive strength and flexibility of neat cement improve by 20%. The SEM-based microstructural analysis of cement composites showed various mechanical property enhancement mechanisms (filling effect, nano-core effect, bridge effect, and pinning effect) of BHNCMs.

Improving Saudi Class G Oil-Well Cement Properties Using the Tire Waste Material.

After oil and gas well drilling, they should be cased and cemented to ensure the stability of the wellbore and to isolate the trouble zones. To achieve these jobs, several additives are incorporated into the cement slurry to improve the cement matrix durability, especially at temperatures above 230 F. The tire waste material is an industrial waste that comes from automobile tires. The purpose of this work is to investigate the prospect of utilizing tire waste in oil-well cement under high-temperature and high-pressure conditions of 292 F and 3000 psi. Three cement samples with different concentrations of the tire waste material were prepared. The effects of tire waste on the cement rheological properties, elastic and failure parameters, and permeability were examined. The results showed that adding 0.3% by weight of cement (BWOC) of the tire waste material considerably improved the cement to the cement slurry and cement matrix properties, and it decreased the cement plastic viscosity by 53.1% and increased its yield point by 142.4% compared to the base cement. The cement samples with 0.3% BWOC of tire waste have Young’s modulus which is 10.8% less than that of the base cement and Poisson’s ratio of 14.3% greater than that of the base cement. By incorporating 0.3% of the tire waste, both compressive and tensile strengths of the cement increased by 48.3 and 11.7%, respectively, compared with those of the base cement. The cement permeability was decreased by 66.0% after adding 0.3% of the tire waste. Besides the improvement in the properties of cement, the use of the tire waste material has other economical and environmental advantages because these are very cheap materials dominant in our life.

Improved durability of Saudi Class G oil-well cement sheath in CO2 rich environments using olive waste

The physical properties of the oil-well cement, especially its strength and permeability, are changing significantly after reacting with CO2-saturated brine which will alter the cement hydration products. In this study, the effect of incorporating the olive waste into Saudi Class G oil-well cement formulation subjected to CO2 sequestration conditions at 130 °C and 10 MPa on the cement permeability, carbonation depth, compressive and tensile strength, and microstructural changes during 20 days of carbonation was evaluated. The results obtained showed that the addition of 0.1% by weight of cement (BWOC) of the olive waste to the cement enhanced the cement resistance to the carbonation process and decrease the carbonation depth from 1469 μm for the base cement to 1269 μm after 20 days of carbonation. Incorporating 0.1% BWOC of the olive waste into the cement slurry also maintained the original cement permeability of 14.3% less than that for the base cement, while the permeability of the cement samples with 0.1% BWOC olive waste after 20 days of carbonation is 33.9% lower than the base cement permeability. The permeability reduction is the main mechanism responsible for the enhancement of carbonation resistance for the olive waste-based cement. The ability of the olive waste to delay calcium leaching is attributed to the decrease in the permeability of the sample with 0.1% BWOC of olive waste.