Oilwell Cement Slurries Research Articles

Effect of Hemihydrate gypsum on the basic properties of oil-well cement

The purpose of the study was to determine the influence of gypsum in different phase states (dihydrate or hemihydrate), an active additive of granulated blast furnace slag, and the total SO3 content on free water separation, the spread of well cement slurry, and the flexural and compressive strength of cement mortar. Laboratory and production cement mills were used to compare the results. The conducted research cycle enabled the quantitative determination of these parameters. Gypsum was preheated in a furnace at 200 °C for 60 minutes. It was found that the presence of hemihydrate gypsum in the cement does not significantly affect free water separation but has some impact on the spread of the well cement slurry. Additionally, the study revealed the influence of hemihydrate gypsum on compressive strength at 28 days and flexural strength at 1 day. The research also discovered that the presence of hemihydrate gypsum in the cement reduces the thickening time by 60 minutes. The presence of granulated blast furnace slag in the cement reduced free water separation in the well cement slurry. The research conducted at the production cement mill confirmed that the presence of hemihydrate gypsum in the cement reduced the spread by 25 mm and free water separation by 1 ml. The results from the production cement mill and laboratory mill are comparable and representative.

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.

Effects of compressive cyclic loading on the fatigue properties of oil-well cement slurries serving in deep downhole environments

With the increasing demand for energy from deep oil and gas reservoirs, oil-well cement slurries are subjected to complex compressive cyclic loading in high-temperature and high-pressure (HTHP) environments. Currently, no standard to guide the evaluation of the fatigue performance of cement slurries under cyclic loading or a systematic investigation to help understand it exists. To fill this gap, this study used a set of innovative HTHP curing and testing devices to mimic the actual operating conditions of deep wells. Cement slurries were cast, cured, and subjected to quasi-static and cyclic loading tests at four downhole temperatures (25, 90, 115, and 140 °C). In the cyclic-loading tests, three loading levels (30%, 50%, and 70%) under 20 MPa confining pressure were applied to study the fatigue performance, and nuclear magnetic resonance (NMR) was employed to identify internal microcrack damage. When the downhole temperature increased from 25 to 140 °C and the cyclic loading level increased from 30% to 70%, the accumulated plastic strain of samples increased by 13.8 times. A large increase in the plastic strain of oil-well cement slurries can significantly reduce the fatigue resistance and service life of oil and gas wells. Based on this research, the authors propose the addition of compressive cyclic loading tests (particularly under HTHP testing conditions) to the current oil-well cement slurry testing standards, which will be very significant for the fatigue performance evaluation of cement slurries used in HTHP environments in deep wells.

The Effect of Gypsum/Bassanite on the Retardation of Ethylene Diamine Tetra(Methylene Phosphonic Acid) Sodium in Oil Well Cement Slurry

Summary Organophosphonates are commonly used retarders to prolong the thickening time of oilwell cement slurry at medium and high temperatures. In this paper, the impact of calcium sulfate in cement on the retarding effect of ethylene diamine tetra(methylene phosphonic acid) sodium (EDTMPS) was explored. First, the thickening properties of cements from four different factories were studied in detail with varying additions of EDTMPS. The study revealed diverse thickening phenomena, including retarding, accelerating, and increasing the initial consistency of cement slurries. The heat flow of cement hydration was detected, and the mineral changes of cement slurries at the early stage (1–3 hours) were analyzed. Additionally, the effect of EDTMPS on the hydration of tricalcium aluminate (C3A) and gypsum (GP)/bassanite (BS) slurry was investigated through X-ray diffraction (XRD) and ion concentration test. Finally, two clinkers from the same cement factory were mixed with GP/BS of different dosages to study the effect of calcium sulfate type on the thickening properties of cement slurry with EDTMPS. The results revealed that EDTMPS slowed down the dissolution of GP while promoting the dissolution of C3A. The rapid hydration of C3A increased the consistency of cement slurry without the retarding effect of GP. However, EDTMPS promoted the dissolution of BS, which can retard the hydration of C3A. Therefore, EDTMPS is appropriate for cements containing BS.

Mechanical performance of oil-well cement slurries cured and tested under high-temperatures and high-pressures for deep-well applications

The American Petroleum Institute testing standard (API TR 10TR7) recommends determining the mechanical performance of oil-well cement slurries in an ambient-temperature testing environment. However, with exploration and exploitation resources moving toward deep formations, cement slurries for oil, gas, and geothermal wells are increasingly being utilized in high-temperature and high-pressure (HTHP) in-site formations. It is unknown if the current standard is suitable for assessing the mechanical performance of cement slurry under in-site HTHP conditions in deep wells. To fill this research gap, an innovative experimental platform was developed for this study to mimic the in-site HTHP environments in real production wells; then oil-well cement slurries were cast, cured, and tested at elevated temperatures (i.e., 90 °C, 115 °C, 140 °C) and the confining-pressure (i.e., 20 MPa). The mechanical performance of cement slurries was evaluated under triaxial compression and cyclic loads. The microstructures of cement slurries were also studied. This study revealed that the high-temperature testing environment accelerated the crack propagation and stress drop of stress-strain curves, decreased the failure stress (up to 14.0 %), Young's modulus (up to 16.4 %), and Poisson's ratio (up to 31.7 %), and resulted in more brittle characteristics of cement slurry samples. This study confirmed that using the current standard will significantly overestimate the mechanical properties of oil-well cement slurries in HTHP environments. The authors suggest updating the standard to take HTHP environments into consideration, which should ultimately meet the increasing demands of developing deep oil, gas, or geothermal wells.

Preparation and mechanism of tartaric acid-intercalated hydrotalcite retarder for oil-well cement

In view of the existing problems of retarding agents, such as abnormal cementing of cement slurry, slow development of cement strength, low strength, poor thermal stability and excessive retarding, etc. In this study, tartaric acid-intercalated hydrotalcite (Mg/Al-TA-LDH) was prepared by ion exchange between tartaric acid and magnesium–aluminium hydrotalcite (Mg/Al-CO3-LDH). The results show that Mg/Al-CO3-LDH and Mg/Al-TA-LDH have typical structural characteristics of hydrotalcite. The interlayer spacing of Mg/Al-TA-LDH after intercalation is larger than that of Mg/Al-CO3-LDH prior to intercalation. Measurements of the thickening time and thickening curve of oil-well cement show that the slow release of tartaric acid has a retarding effect on the oil-well cement slurry mixed with the tartaric acid-intercalated hydrotalcite retarder, the effect is stable, and the thickening curve is stable and shows right-angle thickening. Based on the compressive strength test of oil-well cement, the strength increases gradually with the addition of 0.3%–1.0 % Mg/Al-TA-LDH promoting the development of 1 d and 3 d strength of stone cement. When the dosage of Mg/Al-TA-LDH is 1.0%, the 1 d and 3 d strength of stone cement is higher than that of pure cement, and the 3 d strength of stone cement is increased by 99.6%. The development of 7 d strength was inhibited, but the late strength development was still higher than that of pure cement, and the 14 d strength was 33.3% higher than that of pure cement. Tartaric acid-intercalated hydrotalcite can increase the thickening time of oil well cement through the release of tartaric acid, and can significantly improve the compressive strength of oil well cement through the seed promotion effect of hydrotalcite material.

Rheological properties and early mechanical strength of oil-well cement modified by hybrid nano-silica and nano-hexagonal boron nitride

The purpose of this study was to investigate the effect of the content of hybrid nano-silica (NS) and nano-hexagonal boron nitride (h-BN) on the rheological properties and early mechanical strength of oil-well cement using response surface methodology (RSM). Based on the microstructures revealed by X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy, the modification mechanism of cement mixed with a hybrid of NS and h-BN in the early stage of hydration was studied. It was found that the rheological properties of fresh oil-well cement slurries with added NS and h-BN conformed to those of Bingham fluids. An increase in NS content worsened the fluidity of the cement, whereas the h-BN content did not affect its fluidity. The early compressive, flexural, and splitting tensile strengths at the end of the 3-day curing time increased by 12.33 MPa/47.24 %, 1.88 MPa/29.01 % and 1.24 MPa/53.22 %, respectively. The pozzolanic reaction of NS begins to occur in the early stages of cement hydration. The synergistic effect of the added NS and h-BN increased the density of the early hydration product of the cement. The h-BN mainly enabled the bridging, filling, and crack-resistant effects in the early oil-well cement.

Effect of micro-magnesium oxide admixture on rheological and compressive strength properties of class G well cement

Rheological property tuning is one key aspect of oil-well cement, not only affecting the cement slurry placement but also indirectly impacting other cementing properties such as the bonding strength and compressive strength. However, the research is scant on the rheological properties of blending magnesium oxide with class G oil-well cement, despite some studies having been conducted on its impacts on shrinkage compensation, compressive strength, bonding strength, and permeability properties of oil-well cement. This work studies the effects of micro-sized magnesium oxide on the rheological properties and compressive strength of the formulated API Class G oil-well cement slurries. Two types of micro-sized magnesium oxide (50 μm and 100 μm) were used as the mineral admixture at different dosages (3%, 9%). The base formulated slurry sample was incorporated with the silica flour and several commercialized additives such as retarder, fluid loss control agent, and defoamer. A batch of flow tests have been conducted by the use of a digital viscometer at two different temperatures, 25 and 88°C. The compressive strength has also been measured after curing the samples with the same formulation and conditions for 7 days. The variations of the rheological properties (plastic viscosity, yield stress, and gel strength), shear stress–shear rate correlations, and shear-thinning/thickening behavior are impacted by the temperature, the type, and dosage of magnesium oxide. The plastic viscosity of the tested slurries decreased by 27.0% (type II, 9%, 25°C) and 15.1% (type II, 3%, 88°C), respectively, and the yield stress increased by 258.5% (type II, 3%, 88°C) and 53.9% (type II, 9%, 25°C). The gel strength generally increases as the magnesium oxide dosage increases. However, all tested slurry samples show shear-thinning behavior and non-Newtonian characteristics. Among the tested slurry samples, it is found that better rheological performance is achieved when incorporating magnesium oxide with a smaller particle size. On the other side, the specimens of mixed magnesium oxide with a bigger particle size and medium dosage outperform their rival with a smaller particle size in compressive strength.

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.

Quantitative determination of the hydrostatic pressure of oil-well cement slurry using its hydration kinetics

This study investigated the hydration kinetics and microstructure of oil-well cement slurry in the early hydration stage using calorimetry, X-ray powder diffraction, thermogravimetry, scanning electron microscopy, and X-ray computed tomography to reveal the hydrostatic pressure reduction mechanism and the quantitative relationship between the hydration kinetics and hydrostatic pressure of the cement slurry. The results showed that the time-varying characterisation of the hydrostatic pressure of the cement slurry was in accordance with the Arrhenius equation. During the hydrostatic pressure reduction of the cement slurry, its microstructure developed from “suspension particles” to a “particles framework,” and the “framework” bonded to external interfaces. The hydration products strengthened the “framework” and decreased the porosity, pore size, and connectivity of the cement slurry, leading to the gravity of the entire cement slurry being supported by external interfaces and the slurry lost hydrostatic pressure. Hydration kinetics indicated that the cement slurry hydrostatic pressure changed linearly with hydration heat increments. Using hydration heat increments, a prediction method which successfully predicted the hydrostatic pressure of oil-well cement slurry was developed.

Experimental Investigations on the Effect of Mixing Procedures on the Rheological Properties of Oilwell Cement Slurries

Abstract Well cementing is an essential operation in the oil and gas industry, and it is a key material to ensure wellbore integrity through the life of the well. Improper cement design can trigger well construction risks such as de-bonding and leakage pathways near-wellbore and through the annulus. Mixing non-Newtonian fluids is one of the most challenging tasks, especially for pseudoplastic fluids exhibiting yield stress, such as wellbore cement slurry. Mixing conditions for cement slurries and their effect on rheological properties and thickening time have been debated through the literature. In this study, based on laboratory-scale experiments, we provide testing results for rheological properties and thickening time by changing mixing conditions. Our results show that slurries mixed under similar mixing energy do not necessarily result in similar rheological properties. Comparing rheological measurements from lower mixing energy to higher mixing energy, plastic viscosity decreases; however, yield point increases. This implies the dual opposite effect of mixing time on rheological properties. This may have severe implications for field operations where mixing must be improved to enable successful cement operation.

A Brief Review of Gas Migration in Oilwell Cement Slurries

Gas migration in oil and gas wells is defined as gases and/or fluids from adjacent formations invading a freshly cemented annulus. During well completions, gas and/or fluids can migrate to zones with lower pressure or even to the surface. Static gel strength (SGS), related to the yield stress of the cement, is a widely accepted measurement used to predict and minimize gas migration. In this review article, we look at the mechanisms and some possible solutions to gas migration during oil and gas well cementing. The use of static gel strength (SGS) and experimental measurements for SGS and wellbore pressure reduction are discussed. Rheological properties, including the yield stress and the viscosity of cement slurries, are also briefly discussed. Understanding the rheological properties of cement is complex since its material properties depend on cement type, as well as the shape and size distribution of cement particles. From this brief review, it is evident that in order to reduce free water and settling of the cement particles, to lower fluid loss, and to develop compressive strength in the early stages of cementing, an optimal cement slurry design is needed. The SGS test is a standard method used in estimating the free water in the well and could be a reference for gas migration reduction for oilwell cement slurries.

Visualization and quantification of pore structure of oil-well cement slurry in liquid-solid transition stage using high-resolution computed tomography

Understanding the pore structure of oil-well cement slurry during early hydration is key to resolving short-term gas migration in natural gas wells. This study evaluated the three-dimensional microstructure and pore structure of oil-well cement slurry during early hydration using in situ high-resolution X-ray computed tomography and image reconstruction techniques. Experimental results showed that in the initial hydration stage the microstructure of the oil-well cement slurry comprised ‘dispersed particles’. When the hydration rate increased, some hydration products formed between the dispersed particles, and the microstructure of the slurry changed from a ‘dispersed particles’ structure to an ‘agglomerated skeleton’ structure. Furthermore, when the hydration time increased from 180 to 600 min, the porosity of the slurry decreased from 11.46% to 10.14% (a 11.52% decrease), the porosity of pores with volumes of 201 or more voxels reduced from 2.96% to 1.81% (a 38.83% decrease), and the connected porosity decreased from 4.47% to 2.26% (a 49.47% decrease). These results indicate that during early hydration, the formation of hydration products reduces the pore volume and cuts off some connected pores to produce many pores with small volumes. Based on the Kelvin−Laplace equation, the reduction in pore size increases the capillary pressure of the pore solution and shifts the weight of the pore solution acting on the agglomerated skeleton to reduce the hydrostatic pressure of the slurry. This study further proves that the pore structure of oil-well cement slurry is a key factor in reducing hydrostatic pressures and enabling short-term gas migration.

Effect of Acid Activation-Hydrophilic-Modified Sepiolite on Comprehensive Properties of Oil-Well Cement

In this paper, sepiolite was treated by acid activation, coupling agent treatment, and sulfonation modification. The purpose of this study was to explore the changes in the fluidity and mechanical properties of sepiolite cement slurry before and after modification. Therefore, the comprehensive properties of unmodified sepiolite fiber (HPS) and acid activation-coupling agent treatment-sulfonated sepiolite fiber (S-O-H-HPS) in oil-well cement slurry were evaluated. FT-IR and microscopic mechanism of cement paste fracture surface before and after sepiolite modification were analyzed. The results showed that HPS can effectively improve the toughness of cement paste, but when the content of HPS was more than 1%, the fluidity of cement paste deteriorated sharply and the compressive strength decreased gradually. The addition of S-O-H-HPS can significantly improve the fluidity and stability of HPS slurry. Without affecting the compressive strength, it can effectively improve the flexural strength and impact strength and reduce the elastic modulus of cement paste. The mechanism analysis showed that S-O-H-HPS can not only form network structure in cement paste but also improve the toughness of cement paste by forming a bridge. This also explains why the strength of S-O-H-HPS cement paste does not decrease significantly with the increase of S-O-H-HPS.

Effect of Nano-SiO2, Nano-TiO2 and Nano-Al2O3 Addition on Fluid Loss in Oil-Well Cement Slurry

In this article, incorporation of nano-SiO2 (NS), nano-TiO2 (NT) and nano-Al2O3 (NA) particles and their binary and ternary blends on water filtration in oil-well cement slurry was examined. The nanoparticle contents were chosen at proportions corresponding to 1, 2, 3 and 4% based on the weight of cement. The experimental specimens were tested at three various temperatures of 70, 80 and 90 °C using a gas pressure of 1000 psi. The quantity of water filtrate collected was measured in milliliter (mL) at 30 min after the test begins. The results consistently indicate that an additional of NS, NT and NA particles independently, reduced the loss of liquid in cement, and its performance varies with temperature and the nanoparticle dosages. The 3% NS usage delivered strong evidence in lessening fluid loss compared to the other results by reducing the loss up to 72%. When collective impact of nanomaterials was determined, the fluid retainment was also improved. The replacement of 4% NST reduced fluid loss by the most compared to NSA and NTA binary groups. In-case of ternary combination, NSTA showed a highest reduction of the water loss by 58–60% likened to the plain samples at the concentration of 4%. The key investigation of this paper clearly suggested that the efficacy of Class G cement having nanoparticles to trap its water is dependent on the nanoparticle contents. The lessening of water filtration might be explicated by the filling capability of nano-scale particles. Nanoparticles can plug the openings within the oil-well cement slurry matrix, thus promoting the retainability of water. Besides, nanoparticles quickens the hydration products by creating dense interlocking C–S–H gels for bridging cement grains and forming enclosed structure which can stop the liquid from escaping the slurry.

Oil Well Cement for high temperature-A review

Oil well cement (OWC) are widely used in oil industry both in exploration and in production of oil and gas. The purpose of OWC is to seal the annular space between metal casing and walls of a borehole. OWC has other application such as grouting and repair of offshore structure, and in cementing of other wells likes as water, waste disposal, geothermal, injection or storage. There are numerous problems such as high temperature and high pressure in the downhole condition of oil well. OWC slurry undergoes a reduction in strength (strength retrogression) with time when exposed to high temperature and high pressure. This paper reviews the OWC and its classifications, hydration process at ambient and higher temperature. Moreover, this study provides a comprehensive insight on anti-strength retrogression additives, which can potentially be use with OWC at high temperature and pressure.

Effect of the hydration rate and microstructure of Portland cement slurry on hydrostatic pressure transfer

In cementing operations in oil and natural gas wells, the reduction in hydrostatic pressure of the oil-well cement (OWC) slurry is a serious threat to the quality and safety of the operations. To elucidate the mechanism of hydrostatic pressure transfer in OWC slurries, this study investigates the rules for the hydrostatic pressure transfer of OWC slurries using a hydrostatic pressure testing device. In addition, static gel strength (SGS) analysis, isothermal calorimetry, low-field nuclear magnetic resonance (LF-NMR), environmental scanning electron microscopy (ESEM), and X-ray computed tomography (μ-CT) were used to study the effects of the SGS, hydration rate, pore water, and microstructure on the hydrostatic pressure of OWC slurries. The experimental results show that the trends in the hydrostatic pressure curves of the cement slurries are similar. The hydrostatic pressure and SGS of the cement slurries vary exponentially, while the hydrostatic pressure and free water content vary linearly. Combined with the SGS results, the hydrostatic pressure curves can be divided into two stages. The first stage encompasses the range from the initial hydrostatic pressure to a pressure approximately equal to the hydrostatic pressure of water. From the hydration rate and microstructure results, it can be ascertained that this hydration stage is a dynamic balance stage. The microstructure of the cement slurry will be changed from a dispersed particles state to the gelation state, which increase the SGS of the cement slurry and the bonding ability between the cement particles and the interfaces of the casing and borehole. Part of the gravitational force of the cement particles acts on these interfaces, which reduces the hydrostatic pressure. The hydrostatic pressure in the second stage is less than that of water. This hydration stage is an acceleration stage, and the rapid hydration reactions form a large number of hydration products in the pores, which change the microstructure of the cement slurry from the gelation state to a solid state. The LF-NMR results indicate that the hydration products also reduce the pore size of the cement slurry, which causes the free water in the macropores to become capillary water and gel water. However, in the cement slurry, the hydrostatic pressure is not readily transferred by capillary water and gel water.

Evolution of pore structure of oil well cement slurry in suspension–solid transition stage

This study investigates the pore structure of oil well cement slurry (OCS) in the suspension–solid transition stage and the effect of the hydrated products on the pore structure via isothermal calorimetry, scanning electron microscopy (SEM), nitrogen adsorption, thermogravimetry (TG), and low-field nuclear magnetic resonance (LF-NMR). The experimental results show that the suspension–solid transition stage of OCS includes a dynamic balance stage and an acceleration stage. The porosity of the fresh cement slurry is approximately 58.09%, and its pore sizes range from 100 nm to 850 nm. In the dynamic balance stage, a small quantity of formed hydrated products between the cement particles cause the OCS macropore structure (>250 nm) to transform into capillary pores (50–250 nm). In the acceleration stage, amorphous calcium silicate hydrate (C–S–H) gel quickly forms in the pores and on the surface of the cement particles, which causes the capillary pores to transform into gel pores (<50 nm). When the OCS is in the solid state (hydration of 720 min), the pore sizes range from 0.6 nm to 99 nm, and the total porosity and porosity of the gel pores are 53.64% and 46.218%, respectively. Further, during the suspension–solid transition stage, the porosity of the cement slurry only decreases from approximately 58.09% to 53.64%. However, the pore size distribution (PSD) decreases from 100–850 nm to 0.6–99 nm, which proves that the pore structure of the cement slurry undergoes a disassembly during this stage. This study provides experimental data for understanding the mechanism of hydration and gas migration in OCS.

Influence of Cellulose Nanoparticles on Rheological Behavior of Oil Well Cement-Water Slurries.

Performance of hardened oil well cement (OWC) is largely determined by the rheological properties of the cement slurries. This work was carried out to investigate the effect of water- to-cement ratio (WCR) and cellulose nanoparticles (CNPs), including cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs), on rheology performance of OWC-based slurries using a Couette rotational viscometer coupled with rheological models. The yield stress and viscosity of neat OWC slurries had a decreasing trend with the increase of WCRs. The suspension became increased unstable with the increase of WCRs. The properties of CNPs, including rheological behaviors, surface properties and morphology, determine the rheological performance of CNP-OWC slurries. In comparison with CNC-OWC slurries, the gel strength, yield stress and viscosity of CNF-OWC slurries were higher as CNFs were more likely to form an entangled network. The gel strength, yield stress and viscosity of CNP-OWC slurries increased with reduced CNF size through regrinding and the proportion of CNFs in the mixture of CNFs and CNCs, respectively.

Evaluation of Guinea Corn Husk Ash as Oil-Well Cement Slurry Extender

Evaluation of Guinea Corn Husk Ash as Oil-Well Cement Slurry Extender