Cement Stresses Research Articles

Cement stress and microstructure evolution during curing in semi-rigid high-pressure environments

The process of cement slurry curing into a solid has a direct effect on the initial state of stress in a composite concrete and steel structure. Failure models for critical infrastructure and wellbores could benefit from measurements of this initial stress because it greatly influences structural performance. Here, we present measurements of the initial stress state (total stress, effective stress, and pore pressure) of multiple cement formulations cured under a high-pressure of 40 MPa within a semi-rigid steel pipe. Our results show that cements cured in this restrained environment exhibit dense microstructures with low permeability (nano-Darcy), develop an anisotropic stress state greater than zero and less than the curing pressure, and undergo a staged curing process where hydration and mechanical behaviors evolve from a slurry into a pre-stressed porous medium. Both drained and undrained scenarios were investigated, revealing a feedback from the semi-rigid boundary towards improved cement performance.

Experimental study using ASTM and BS standards and model evaluations to predict the compressive strength of the cement grouted sands modified with polymer

The present article discusses the impact of the different grain sizes of sand on the ultimate stress of hand-mixed cement grouted sand modified with polycarboxylate ether-based polymer using two different test standards (ASTM and BS). The fresh and hardened properties of cement grouted sands modified with polymer up to 0.16 % of the weight of cement were tested and quantified. Five types of sand with different grain sizes were used in this study. Adding polymer decreased the water/cement ratio (w/c) by 21.9–54.1%, and it kept the flow time of the cement-based grout in the range of 18–23 s. Adding polymer creates an amorphous gel that fills the porous between the cement particles, which causes a reduction in the voids, porosity and enhanced the dry density of the cement; subsequently, the compression strength of the cement-grouted sands increased significantly. Linear and nonlinear approaches were employed to estimate the compressive strength of cement grouted sand with a different grain size of sand, w/c, amount of polymer, and curing age. The compressive strength of the cement grouted sands following the BS standard was 71 % larger than the compression strength of the same mix using the ASTM standard.

Technology Focus: Cementing and Zonal Isolation (May 2021)

Wow! What a year it has been! We have experienced enormous upheavals in our professional and social circles and wholescale changes in the way that we interact with each other. As engineers, though, we recognize that in every challenge there is an opportunity. I have been lucky to attend SPE online events, including a happy hour and a webinar on geothermal energy. As we witness a shift to renewable energy, I note that 2020 SPE President Shauna Noonan highlighted that our SPE professional expertise in the subsurface will be needed to both maintain existing energy production and develop new sources of energy. Cementing, zonal isolation, and well integrity continue to be an important piece of the puzzle. This year, in the presence of enormous challenges, the selected papers demonstrate step changes both in efficiency and in the results of cementing operations. Managed-pressure cementing extends the benefits of managed-pressure drilling, and a successful case is described in paper OTC 30481. Last year, we read about offline cementing in North America. Offline cementing continues to increase rig efficiency, and wellhead equipment that enables offline cementing is described in paper SPE 202439. Improving cementing results by enabling casing rotation with rotating cement heads is discussed in paper SPE 198970. Research that will enable future successful changes also continues. Although not summarized in this edition, extra reading is recommended for interesting discussions on proving shale as a barrier (SPE 200755), cement properties and initial state of stress in confined pressure conditions (SPE 201770), and the evaluation of neutron logging as a possible cement evaluation tool (SPE 202973). As an industry, we also continue to investigate materials that will provide effective isolation in the annulus. Papers about self-healing systems (SPE 203174), epoxy (SPE 202648), and expanding metal sealing systems (SPE 203354) are also recommended as extra reading. Although it has been a challenging year, operational improvements, research, and material investigation continue to provide engineering opportunities in cementing and zonal isolation. Recommended additional reading at OnePetro: www.onepetro.org. SPE 200755 - Innovative One-Trip System Helps Qualify Creeping Shale as Permanent Barrier for Plug and Abandonment of Wells on the Gyda Field by Thore Andre Stokkeland, Archer, et al. SPE 201770 - Laboratory Measurement of Cement Stress Before, During, and After Curing Under Undrained Condition With Constant Hydrostatic Pressure by Meng Meng, Los Alamos National Laboratory, et al. SPE 202973 - Potential Usage of Neutron Logging Technology for Casing Cement Evaluation—Feasibility Study by Espen Dommersnes, University of Stavanger, et al. SPE 203174 - A Game-Changing Technology for Cementing in Highly Deviated and Horizontal Wells Using Interactive Mud-Sealing Cement System by Choosak Orprasert, Mubadala Petroleum, et al. SPE 202648 - Primary Cementing Using Epoxy Resins as Additive: Experimental and Application by Khawlah Abdulaziz Alanqari, Saudi Aramco, et al.

ANGULATED DENTAL IMPLANT VERSUS VERTICAL ONE FINITE ELEMENT STUDY

Aim: The aim of this study is to evaluate the effect of different implant angulations under different crown materials on surrounding bone stress distribution using finite element. Methods: Two simplified models were prepared for molar crown supported by implant placed vertically and tilted 25° in simplified mandibular bone geometry. Geometric models' components were prepared on Autodesk Inventor then assembled in ANSYS for finite element analysis. Each model was subjected to two loading cases as 150N compressive load at central fossa and 50N oblique load at mesio-buccal cusp tip.Results: The values of total deformations and Von Mises stresses showed minor difference when changing load position and angle. On the other hand, crown and cement were considerably affected by crown material selection. Also, results showed insensitivity of mucosa, implant complex, cortical and cancellous bone to changing crown material.Conclusion: It was found that the implant complex and bone are showing jump in values of stresses and deformations by changing implant angle and/or loading position and angle. While, crown and cement stresses decreased with decreasing crown material rigidity leading to better load distribution at bone implant interface. Implant fixture, mucosa, cortical and cancellous bone were not sensitive to crown material.

Effects of conform, non-conform, and hybrid conformity toward stress distribution at the glenoid implant and cement: A finite element study.

Glenoid conformity is one of the important aspects that could contribute to implant stability. However, the optimal conformity is still being debated among the researchers. Therefore, this study aims to analyze the stress distribution of the implant and cement in three types of conformity (conform, non-conform, and hybrid) in three load conditions (central, anterior, and posterior). Glenoid implant and cement were reconstructed using Solidwork software and a 3D model of scapula bone was done using MIMICS software. Constant load, 750 N, was applied at the central, anterior, and posterior region of the glenoid implant which represents average load for daily living activities for elder people, including, walking with a stick and standing up from a chair. The results showed that, during center load, an implant with dual conformity (hybrid) showed the best (Max Stress-3.93 MPa) and well-distributed stress as compared to other conformity (Non-conform-7.21 MPa, Conform-9.38 MPa). While, during eccentric load (anterior and posterior), high stress was located at the anterior and posterior region with respect to the load applied. Cement stress for non-conform and hybrid implant recorded less than 5 MPa, which indicates it had a very low risk to have cement microcracks, whilst, conform implant was exposed to microcrack of the cement. In conclusion, hybrid conformity showed a promising result that could compromise between conform and non-conform implant. However, further enhancement is required for hybrid implants when dealing with eccentric load (anterior and posterior).

Parametric Study of Mechanical Stresses within Cement Sheath in Geothermal Wells

A cement sheath, placed between the casing and the formation, is an important barrier that establishes a hydraulic seal and provides zonal isolation, preventing fluid communication in the wellbore. In geothermal wells, stress induced by high bottom-hole temperature is one of the major factors triggering failure in the cement sheath. However, the influence of heat flow direction and differential temperature, relative to other design and operating factors, is not well understood. The objective of this paper is to investigate these two important factors.In this study, an analytically verified 2D numerical model was used to perform a parametric study of mechanical stress within a cement sheath. Loading conditions applied to the model included maximum and minimum horizontal formation stresses, wellbore pressures, and temperature differences. Sensitivity analysis was conducted to understand the effect of cement properties, temperature difference between the casing and the formation, and casing pressure on stresses in the cement sheath. Sensitivity response curves demonstrated the relative influence of investigated parameters on radial and hoop stresses. Results showed that heat transfer from the formation to the casing (Ti < Tf) is more detrimental to cement integrity than the opposite scenario (Ti> Tf). When heat flows away from the wellbore, hoop stress in cement is mainly dependent on temperature difference, while radial stress is primarily dependent on temperature difference as well as wellbore pressure. When heat flows toward the wellbore, radial stress in cement is primarily a function of temperature difference and wellbore pressure. Hoop stress, on the other hand, is mainly dependent on temperature difference and the cement’s thermal expansion coefficient.

Numerical modeling of casing collapse in Gachsaran formation in Sirri-E oilfield in Persian Gulf

Casing collapse is a costly phenomenon in drilling industry that occurred in different geological environment with different geomechanical property. Geomechanical and numerical analysis of casing collapse in Sirri-E, one of the offshore Iranian oilfield in Persian Gulf has been investigated in this work. In this study we tried to model several collapse loading of rock-cement-casing system under real condition of in-situ stress and geomechanical property of different lithology, cement and casing, to decrease simplified modeling assumption. A mechanical earth model is built to determine the accurate amount of in-situ stresses and different mechanical property of rock. This geomechanical data extracted from 1D geomechanical earth model and entered to numerical model involved formation, cement and casing. Furthermore the interactions between the casing and surrounding formation are simulated by applied elastic-plastic behavior for rock and cement. Also Joint property between different media considered to increase the accuracy of model to real condition of borehole at the collapsing depth. The result show that over pressured marl and salt have high potential for casing collapse and the maximum external load applied to the casing is very more than maximum mud weight that usually considered in API standard for design of casing. So it is necessary to use coupled data from mechanical earth modeling and numerical analysis to determine maximum lithostatic pressure applied to the casing. • not only high in-situ earth stresses, rather Geomechanical behavior of rock under in-situ stresses is an important factor for the amount of stresses that transmitted to casing. • Geomechanical earth modeling coupled numerical analysis is necessary for casing design in plastic formation. • Overlapping casing can decrease external load applied to the innermost liner about 50%. Abstract.

Influence of post-core material and cement peculiarities on stress of post-cores under ultrasonic vibration: a three-dimensional finite element analysis.

To analyse the effect of post-core, and cement materials and thickness of the cement lute on the stress in post-core systems under ultrasonic vibration at different frequencies and amplitudes using three-dimensional finite element analysis. Eight three-dimensional finite element models of a maxillary central incisor with post-cores were established. Two post-core materials (Au and Ni-Cr alloys), two cements (glass ionomer (GI) and zinc phosphate (ZP)) and two cement layer thicknesses (50 and 150μm) were considered. Vibration loads were applied near the neck on the buccal side of the core at frequencies of 10-40kHz and amplitudes of 10-50μm. The maximum shear stress of the cement layer and maximum principal stress of the roots and their distributions were investigated. The stresses on cements and roots increased with an increase in the frequency and amplitude of the vibration load and elastic modulus of the cements, and decreased with increasing thickness of the cement layer and elastic modulus of the post-core. Maximum cement stress was observed on the contralateral upper part of the loading side, whereas the maximum root stress was found on the ferrule where the load was applied. In this simulated model, the frequency and amplitude of ultrasound needed to remove a post-core were positively related to the elastic modulus of the post-core and thickness of the cement layer and negatively related to the elastic modulus of the cements.

Mechanical response and damage mechanism of cement sheath during perforation in oil and gas well

Perforation will damage the cement sheath around the hole in petroleum engineering, leading to the failure of cement sealing integrity during hydraulic fracturing. This work presents a perforating experiment in real size to investigate the damage mechanism of cement sheath. The crack characteristics inside the cement after perforation were statistically analyzed by computerized tomography (CT). Then, a numerical model was introduced to describe the effective stress state in cement sheath during perforation based on ANSYS/LS-DYNA software. The damage zone around the hole in cement sheath was partitioned by the peak stress of cement during perforation. The results show that damage zone was formed by the surface pressure around the hole after the shaped jet passed through the cement. The toothed micro-cracks around the tapered hole are close to the cement/formation interface. The cement with lower shear modulus and higher strength can reduce the damage range in cement sheath, and the scheme with lower perforation density and larger perforated phase is more effective to the maintenance of cement sealing integrity during later fracturing process.

Experimental and finite element modelling evaluation of cement integrity under diametric compression

With the increased exploration activity in unconventional and extreme operational environment, well integrity is becoming a challenging problem. Cement sheath, being an important barrier element, should be designed properly for adaptation of complicated loads surrounding the wellbores. This experimental and modelling study evaluates casing-cement-formation system under diametrically compressive load.Digital image correlation (DIC) technique was employed to examine the strain distribution and failure in experimental setup. A 3D numerical model was developed and the comparison between simulation and experimental results indicated a reasonable match. Using validated model, the effect of cement elastic properties on stresses in cement was studied. The stress distribution in the cement-formation system shows that casing-cement interface is the weakest point in the system, thus it has the highest risk of failure. The failure initiates at orientation parallel (θ = 0°) to the applied load followed by in perpendicular (θ = 90°) direction. Hoop stress is more sensitive to Young's modulus and Poisson's ratio than radial stress, so it is more critical for the failure assessment. In general, flexible cement with low Young's modulus and high Poisson's ratio has low risk of failure.

The measurement of fresh properties of cement-based grout containing waste marble powder

This paper shows the results of an experimental study conducted to investigate the effect of waste marble powder (WMP) on the fluidity (marsh cone flow time (MCFT), mini-slump diameter and plate cohesion meter (PCM)) and the rheological properties (viscosity and yield stress) of cement based grout (CBG) mixtures. The experiments were done with the CBG mixture including 0.75, 1.00, 1.25, 1.50 water-binder (w/b) ratios and 5, 10, 15, 20 and 25% content of WMP. Test results illustrated that the rheological properties of the CBGs had been improved greatly by the addition of WMP to grout mix at various w/b ratios. It was observed that the CBG mixtures showed a strong shear thickening behavior all WMP content and all w/b ratios. Moreover, the increase in the w/b ratio decreases the MCFT at the constant WMP content. Additionally, the increase in the percentage of WMP amount up to %15 did not effect on mini slump flow diameter, however the mini - slump flow diameter decreased above %15 WMP.

Effect of Waste Marble Powder and Fly Ash on the Rheological Characteristics of Cement Based Grout

This paper shows the results of an experimental study conducted to research the impact of waste marble powder (WMP) and fly ash (FA) on the fluidity (marsh cone flow time (MCFT), mini-slump diameter and plate cohesion meter (PCM)) and the rheological properties (viscosity and yield stress) of cement based grout (CBG) mixtures. The experiments were applied with the CBG mix including 1.00 water-binder (w/b) ratios and combined use of WMP (5-25%), FA (5-25%) and WMP+FA (10-30% + constant 25%). Test results illustrated that the rheological properties of the CBGs importantly have been improved by the addition of WMP, FA and WMP+FA to grout mix at w/b=1 ratio. Strongly shear thickening behaviour was got from the CBG mixtures the all WMP, FA and WMP+FA content. The increase in the percentage of WMP (5-25%) amount reduced the mini-slump flow diameter. Moreover, the increment in the percentage of FA (5-25%) amount increments the mini slum flow. According to the control sample, the increment in the percentage of WMP (10-25%) amount increased the mini-slump flow diameter for constant FA (25%) content. Also, the increase in WMP amount in the CBG mix, there is no effect on MCFT. Also, MCFT decreased with the increase of FA amount. Especially, FA increased the fluidity of CBG, when the WMP showed negative effect in increase the MCFT in WMP+FA content.

Numerical investigation of influence of defects of the dentition small extent on the stress-strain state of bridge prosthesis and periodontium

The investigation aim is numerical evaluation of polymethylmethacrylate dental bridge and periodontal ligament stres-strain state in the case of tilted premolar and molar in mandible. Plain strain formulation is used via finite element method. Effect of dental cement on results is also studied. Equivalent stresses in dental bridge and periodontal ligament are determined using von Mises and maximum principal stress criteria. Equivalent stresses in cement are determined using Mohr criterion. The study investigated no difference in stres-strain state of dental bridge with and without consideration of cement. The results showed that dental bridge implantation in the case of tilted teeth redistribute and reduce forces acting on periodontal ligament in comparison with tilted vital teeth.

Influence of glenoid implant depth on the bone–polymethylmethacrylate interface

Preservation of glenoid bone stock in shoulder arthroplasty is a general surgical guideline. The objective of this study was to investigate the influence of implant depth on the mechanical behaviour of the bone–cement interface, in order to confirm the general assumption of maximum bone stock preservation. A three-dimensional (3D) model of a scapula was derived from CT scans. Various implant depths (from 0 to 2.0 mm) were modelled using a 3D reaming procedure. Through integration of bone density into the simulation model, a finite element analysis with best-possible patient specificity was conducted. The results show that mostly subchondral bone was removed during the reaming procedure for implant depths between 0.0 and 0.5 mm, whereas mostly cortical bone at the glenoid rim was removed between 0.5 and 2.0 mm. In all simulated load cases, the mean and maximum von Mises stresses as well as tensile and compressive stress within bone cement increased steadily with increasing implant depth. Implant depth has a substantial influence on stress distributions within bone cement. The fatigue stress of bone cement is more likely to be exceeded at higher implant depths, and higher micromotions could contribute to bone resorption and early implant failure in the long term.

Influence of type of cement and their thickness on stress distribution at dentin-cement interface of computer-aided designed glass fiber post: A three-dimensional finite element analysis.

Aim:This study aims to evaluate the effect of type of cement, and their thickness on stress distribution at dentin-cement interface of computer-aided designed glass fiber post using three-dimensional finite element analysis.Materials and Methods:Nine 3D models of endodontically treated maxillary second premolar were divided into three groups according to the adhesive cement used PermaCem (Group I), Variolink II (Group II), and ParaCore (Group III). Each group was further divided into subgroup a, b, and c on the basis of the thickness of the adhesive cement 50 μm, 200 μm, and 300 μm, respectively. All the models were simulated to be cemented with computer-aided designed glass fiber post and core followed by zirconia crown. The core was modeled with incomplete ferrule. The load of 200N at 45° at lingual and central fossa was applied. Maximum von Mises stresses distribution was calculated.Results:Maximum and minimum stresses in dentin were seen in the Ic and IIIa, respectively. Maximum and minimum stresses in cement were seen in IIIc and Ia, respectively.Conclusion:The von Mises stresses in dentin can be minimized by keeping the cement thickness minimum and selecting the cement whose modulus of elasticity is closest to that of dentin.

Biomechanical Behavior of Tooth-Supported Fixed Partial Prostheses Components with Two Different Infrastructures: Metal and Polyether Ether Ketone (Peek).

This study uses the finite element method to assess the biomechanical behavior of tooth-supported fixed partial prostheses components manufactured with two different infrastructures: Cr-Co Fit Flex metallic alloy and Polyether Ether Ketone (PEEK) subjected to physiological occlusal loads. Two models with equal geometry were simulated-Model M1: fixed partial prosthesis with Cr-Co metallic infrastructure and feldspar ceramics coating Noritake Ex-3; Model M2: fixed partial prosthesis with PEEK infrastructure PEEK and indirect resin coating Sinfony. They were subjected to axial and oblique loads. The 3D models were entered in the software CAD Solidworks 2016 for registry and analysis. Data were analyzed according to the studied factors: dentin behavior, infrastructure, aesthetic coating, detachment pressure between tooth and cement, and tensile stress of cement. Most stress peaks were observed in model M2, but values from the two models were close. Model M1 showed better results in four of the factors: dentin, infrastructure, detachment pressure between tooth and cement, and cement tensile stress. Model M2 showed better performance in terms of the aesthetic coating. Similar values for both models in most of the simulations suggest a long lifespan of both treatments, although longer for model M1.

Performance of Cement–Soil Pile Composite Foundation with Lateral Constraint

A lateral constraint can effectively reduce the foundation settlement and reduce the stress of a pile shaft in a foundation treatment. Based on the characteristics of railway engineering and soft soil engineering, this paper studied the influence that lateral constraint exerted on the stress and settlement of cement–soil pile composite foundation by using indoor large-scale model testing. A comparative analysis of the stress and settlement of cement–soil pile and soil following load change is performed, and the mechanism of lateral constraint is discussed. The results show that the settlement of the pile top with lateral constraint is 8–30% lower and that of the soil around the pile is 7–9% lower when comparing the settlement values of the composite foundation with and without lateral constraint in the cement–soil pile composite foundation. The stress value of the pile top in the composite foundation with the lateral constraint is 18–32% lower than that without any lateral constraint. The stress of the cement–soil pile shaft first increases and then decreases with the depth, and the maximum stress appears at 0.15–0.35 times the pile length from the top. The position of the maximum axial force of the pile without a lateral constraint is lower than that with a lateral constraint, and the maximum stress value of the pile is 112–153% of the stress value of the pile top. Therefore, setting the lateral constraint can effectively stop the lateral deformations of soft soil, reducing the settlement of the composite foundation and pile shaft stress.

Non-adsorbing polymers and yield stress of cement paste: Effect of depletion forces

In this work, we study the effect of non-adsorbing polymers with molar masses varying over several decades in both dilute and semi-dilute regimes on the yield stress of cement and calcite pastes. In both suspensions, we measure an increase of yield stress, the magnitude of which mainly depends on the polymer concentration regimes. From interparticle force calculations, we show that non-adsorbing polymers are at the origin of interparticle attractive depletion forces. In the absence of superplasticizers, Van der Waals attractive forces are the dominant flocculating mechanism in the system and depletion forces resulting from non-adsorbing polymers are negligible. The repulsive forces that result from superplasticizers' steric contribution increase the average interparticle distance and therefore decrease the magnitude of the attractive van der Waals forces. In this latter system, attractive depletion forces induced by non-adsorbing polymers become important and greatly contribute to the flocculation mechanism.

Biomechanical comparison of glenoid implants with adaptable and fixed backside curvatures in anatomic total shoulder arthroplasty

We evaluated the biomechanical effects and potential advantages of glenoid implants with adaptable backside curvature radii and compared them with standard implants having fixed backside curvatures in anatomic total shoulder arthroplasty (aTSA) for primary glenohumeral osteoarthritis with uniconcave glenoids. A glenoid implant with adaptable backside curvatures (Aequalis PerFORM, Tornier SAS, Montbonnot, France) was compared with its previous model having a fixed curvature radius. Virtual aTSAs were performed in 24 patients from preoperative shoulder computed tomography data sets, using both implants in each patient. For all 48 simulated aTSAs, we first measured the glenoid bone reaming depth, subchondral bone quality after reaming, and implant backside surface and then the predicted cement stress, bone-cement interfacial stress, and bone strain at 60° of arm abduction. These biomechanical quantities were tested for differences between adaptable and fixed implants and for correlations between preoperative measurements and postoperative predictions. Adaptable glenoid implants induced a significant decrease in cement stress (P = .008), bone-cement interfacial stress (P = .045), and bone strain (P = .039), particularly for glenoids with curvature radii larger than 40 mm. However, these biomechanical effects were not significantly correlated with an increase in subchondral glenoid bone quality. Our study confirms the presumed biomechanical advantages of adaptable glenoid implants, even though the effects were not directly due to the adaptation of the backside curvature radius. Benefits were more pronounced for glenoids with large curvature radii. Our initial biomechanical findings should now be corroborated with large-scale clinical studies.

Feasibility of using sodium silicate as grouting in loose coal bed sections for methane drainage

Incidents such as borehole collapse, suction drill, and drill pipe drop resulting from borehole instability may occur in the process of drilling in loose coal bed sections for coal mine methane (CMM) drainage before mining. Grouting while drilling (GWD) is a technique used to reduce such incidents. Sodium Silicate used in GWD has the advantages of controllable consolidation-time, non-toxic material, non-pungent odor and relatively inexpensive. Although it will shrink after solidification, this could be used to connect gas channels. This paper presents the feasibility of using Sodium Silicate to make GWD slurry through results of laboratory experiments.The principal ingredients of the two Sodium Silicate grouting slurry formulae, namely 4% Glycerol Triacetate with 20–40% Sodium Silicate and 4% 1,4-Butyrolactone with 20–40% Sodium Silicate, were selected based on the requirements of GWD. The experimental results from a traditional test device revealed that coal cement stress is still low after 45 min thus limiting its field application. However, after 72 h, multiple cracks appear along the edge of the coal grains suggesting that the formulae can be used to connect gas channels naturally after hardening. If a PH stabilizer is not added, the optimal grouting time occurs within 20 min. In the process of GWD, the grouting slurry will not consolidate until it is injected into the borehole wall, which is enables the drill pipe to remain clean after grouting. Seepage grouting simulation experiments based on a self-developed device indicate that injecting certain slurry into pre-set positions of a drilling hole by circulation wind pressure is feasible to some extent when drilling in fractured, strongly fractured, and pulverized coal beds. In powder coal, however, it will close the gas channels, and thus cannot be applied.