Cementation Factor Research Articles

Saturation model for pore-type gas hydrate based on additional muddy conductive digital core

Abstract Original natural gas hydrate rock samples readily decompose under environmental changes during extraction, presenting challenges to conventional rock electrical analysis. This results in difficulty obtaining the cementation factor m and saturation exponent n of hydrate samples, thereby complicating the evaluation of hydrate saturation. Therefore, a method for revising the rock electrical parameters by digital core technology is proposed. Utilizing X-ray CT images of artificial gas hydrate samples, digital core models of natural gas hydrates were established. An erosion algorithm was employed to simulate the variation in mud content within the digital core, followed by the calculation of resistivity using the finite element method after meshing. Through analyzing the primary micro-pore structure parameters that influence the rock electrical parameters, the saturation model was subsequently refined. The results showed that the resistivity of hydrate digital core magnifies with increasing saturation of hydrate, tortuosity, and pore-throat ratio, but decreases with increasing coordination number and mud content. The rock electrical parameters were changed with the alteration of micro-pore structure. Based on the relationship between m, n, and micro-pore structure parameters, established a correction equation for them, further improved the Indonesian equation. The saturation of hydrate reservoir in Shenhu Sea area was evaluated using the modified Indonesian equation. The modified equation reduced the relative error from 34.8% to 15.6%, significantly enhanced the calculation accuracy.

Study on Mechanical Properties of Sandy Soil Solidified by Enzyme-Induced Calcium Carbonate Precipitation (EICP)

Earth–rock dams are widely distributed in China and play an important role in flood control, water storage, water-level regulation, and water quality improvement. As an emerging seepage control and reinforcement technology in the past few years, enzyme (urease)-induced calcium carbonate precipitation (EICP) has the qualities of durability, environmental friendliness, and great economic efficiency. For EICP-solidified standard sand, this study analyzes the effect of dry density, amount of cementation, standing time, perfusion method, and other factors on the permeability and strength characteristics of solidified sandy soil by conducting a permeability test and an unconfined compression test and then working out the optimal solidification conditions of EICP. Furthermore, a quantitative relationship is established between the permeability coefficient (PC), unconfined compressive strength (UCS), and CaCO3 generation (CG). The test findings indicate that the PC of the solidified sandy soil decreases and the UCS rises as the starting dry density, amount of cementation, and standing time rise. With the increase of CG, the PC of the solidified sandy soil decreases while the UCS increases, indicating a good correlation among PC, UCS, and CG. The optimal condition of solidification by EICP is achieved by the two-stage grouting method with an initial dry density of 1.65 g/cm3, cementation time of 6 d, and standing time of 5 d. Under such conditions, the permeability of the solidified sandy soil is 6.25 × 10−4 cm/s, and the UCS is 1646.94 kPa. The findings of this study are of great theoretical value and scientific significance for guiding the reinforcement of earth–rock dams.

Calculation and Comparison of Water Saturation in Carbonate Formation by Different Methods

Water saturation is an important governing quality and quantity of the hydrocarbon evaluation, as reserve estimation. The challenge of the reservoir engineer is to resolve and understand the differences distribution of water saturation content by using different techniques. However, though out this work illustrate variety models to calculate water saturation which is compared with core measured. Therefore, water saturation is calculated using different models; Archie, Simandoux, Indonesia which are compared with Leverett J-Function (capillary pressure measurements). Archie's parameters of the studied reservoir rock; Cementation Factor (m) and Saturation Exponent (n) are derived from the log data used. Error of the water saturation estimation may significantly impose bias in the estimation of both quantities. In spite of, there are various factors affecting potential error in water saturation estimation, such as, average permeability, average porosity and Archie's parameters are used. Consequently, the comparison between results indicates that, Indonesia and Simandoux models are show the smallest average absolute error values, where Archie's model common one used for water saturation in Carbonate rocks. Three wells are selected to present his comparison.

Archie's cementation factors for natural rocks: Measurements and insights from diagenetic perspectives

Archie's cementation factor, m, is a critical parameter for petrophysical studies, and the value is influenced by several factors such as the shape, type, and size of grains, degrees of diagenesis, and associated pore structure. Using integrated experimental and theoretical approaches, the goal of this study is to obtain the cementation factor of rocks (both reservoir rock and caprock) and assess the impact of diagenetic processes on the values of the cementation factor. Thirteen samples of geologically diverse rocks (six mudstones, four fossiliferous limestones, two marbles, and one sandstone) were selected to achieve these research objectives. Two approaches, the diffusion of gas tracers and the Bosanquet formula calculation using pore-throat sizes from mercury intrusion porosimetry analyses, were used to derive the cementation factors of these rock samples. These rocks were categorized into two groups based on the correlation between average pore-throat diameter and diffusivity, and an exponential-law relationship between the cementation factor and porosity was determined for these sample groups. In addition, thin-section petrography and field emission-scanning electron microscopy observations were utilized to investigate diagenetic processes, with four diagenetic patterns being established: (1) strong compaction, strong cementation, and weak dissolution-diagenesis pattern; (2) weak compaction, medium cementation, and weak dissolution-diagenesis pattern; (3) weak compaction, medium cementation, and strong dissolution-diagenesis pattern; and (4) fracture-matrix pattern. The results indicated that diagenetic processes and microfractures contribute to the variability in the cementation factors of these rock samples.

Permeability Prediction for Carbonate Rocks using a Modified Flow Zone Indicator Method

Carbonate reservoir rocks are usually heterogeneous, so it is not an easy task to establish a relation between porosity and permeability in these types of reservoir rocks. First, Kozney and Kozney-carmen formulas were used to establish these relations. Later, the flow zone indicator (FZI) method was introduced, which was widely used to find such a relation since it shows better results than the two former methods. In this work, the classical FZI method and a modified form of the FZI method are utilized to identify the hydraulic flow units and rock quality index to predict permeability. In this FZI method, the cementation factor (m) was introduced in calculating the value of FZI. The data collected from core analysis of the cored intervals in the Tanuma and Khasib formations were used as a database for this work. The classical and the modified FZI methods were applied using the database to predict core permeability. The value of the cementation factor was tuned to get a better match between the predicted permeability resulting from applying the modified method and the measured permeability values. Results show that the correlation coefficients resulting from applying the modified FZI method are closer to unity compared with that resulting from the classical FZI method. Cementation factor (m) of m = 3 for Tanuma formation and m = 3 for Khasib formation are the best values used with the modified FZI method. The modified FZI method shows a regression factor of 0.9986 for Tanuma and 0.9942 for Khasib formation.

Determination of Porosity and Formation Resistivity Factor for a Leachate-Saturated Waste

The factors of porosity and formation resistivity have a strong influence on the process of electric current conduction through saturated porous media. In this study, laboratory experiments were carried out to calculate the resistivity formation factor from electrical resistivity measurements for leachate-saturated waste in samples collected from the Bakung landfill in Bandar Lampung. The formation resistivity factor is calculated using the Archie equation by calculating the representative value of the intercept (a) and the cementation factor (m) as used by Archie in the derivative relationship between the formation resistivity factor (F) and porosity (ϕ). This study investigates the impact of leachate spatial distribution on electrical resistivity. Electrical resistivity and porosity were measured in 27 soil samples. Each soil sample was subjected to three treatments: without leachate injection, unsaturated leachate injection (physical modelling), and fully saturated leachate injection (physical modelling). The results show that resistivity formation factors and porosity have a relationship. The values of ‘a’ and ‘m’ were determined at the study site based on the relationship between formation factors and porosity. The findings should create new insights into applied geophysics.

Prediction of cementation factor using different methods of reservoir rock classification in heterogeneous carbonate reservoirs

Cementation exponent or factor is one of most crucial factors in the Archie’s equations that should be estimated precisely in order to accurately determine relevant petrophysical characteristics of the reservoir. Inaccurate estimation of this factor leads to incorrect petrophysical analysis and inaccurate determination of water saturation which is highly important for the economic forecasting of hydrocarbon reservoirs. An alternative to the cementation factor precise estimation is to classify rocks based on a common petrophysical property such as permeability. This research aims to investigate the cementation factor in different rock types and eventually to provide a suitable model for estimating this parameter based on different approaches of rock classification. In this paper, first, conventional methods of rock classification (e.g., current zone indicator (CZI), flow zone indicator (FZI), permeability and electrical efficiency) have been used for cementation factor estimation. Then, the data, taken from Regnet et al. (J Geophys Res Solid Earth 120:790–811, 2015), have been analyzed by these methods in order to find the best way of rock classification. The analyzed data show that only electrical efficiency method is accurate enough to classify rocks into different groups as high values of determination coefficient (i.e., 0.9828 and 0.9725) are obtained as a result of classification by this method in which the data are classified into distinct groups. The obtained values of determination coefficient as a result of classification by permeability, FZI and CZI methods are 0.805, 0.809 and 0.7568 respectively. Due to this result and high scattering of the classified data, it can be concluded that these three methods have not been precise enough for rock classification of the data. In addition to the above-mentioned existing methods, a new rock classification method based on tortuosity coefficient or factor has also been proposed in this paper. This new method has been proven to be accurate due to low scattering of the data results and falling them into distinct groups in addition to obtaining high values of determination coefficient (i.e., 0.9996, 0.9986 and 0.9951) in the classification by this new method.

Analytical Models for Predicting the Formation Resistivity Factor and Resistivity Index at Overburden Conditions

In this study, new parameters referred to as rock resistivity modulus (RRM) and true resistivity modulus (TRM) were defined. Analytical models were developed based on RRM, TRM, and Archie’s equation for predicting formation resistivity factor (FRF) and resistivity index (RI) under overburden pressure conditions. The results indicated that overburden FRF is dependent on FRF at initial pressure (ambient FRF), RRM, and net confining pressure difference. RRM decreases with cementation factor and rock compressibility. The proposed FRF model was validated using 374 actual core data of 79 plug samples (31 sandstone and 48 carbonate plug samples) from three sandstone reservoirs and four carbonate reservoirs, measured under four to six different overburden pressures. The developed FRF model fitted the experimental data with an average relative error of 2% and 3% for sandstone and carbonate samples, respectively. Moreover, the applications and limitations of the models have been investigated and discussed. Further theoretical analysis showed that overburden RI is a function of RI at initial pressure, TRM, and net confining pressure difference. The developed models supplement resistivity measurements and can be applied to estimate FRF, RI, and saturation exponent (n) variations with overburden pressure.

Evaluation of natural and artificial fiber reinforcements on the mechanical properties of cement-stabilized dredged sediment

The combination of chemical stabilization and fiber reinforcement can simultaneously improve the strength and ductility of dredged sediment. The polypropylene fiber (PF) and straw fiber (SF) were respectively used as artificial and natural reinforcements of cement-stabilized dredged sediment (CDS). A series of unconfined compressive strength (UCS) tests were conducted to investigate the effects of cement content, fiber content, fiber length and water content on the mechanical properties of PF-reinforced CDS (CPFDS) and SF-reinforced CDS (CSFDS). Furthermore, the cementation-reinforcement mechanism was explored and analyzed via macro failure characteristics and micro interfacial morphologies inside typical CPFDS and CSFDS samples. The results showed that increasing cement content or decreasing water content significantly improved the UCS and aggravated the brittleness of CPFDS and CSFDS. The suitable addition of PF can effectively improve the UCS of CDS, while incorporating SF exhibited the opposite role. The maximum 7d-, 28d-, 60d- and 90d-UCS of CPFDS were respectively 17.7%, 43.6%, 10.7% and 9.7% higher than that of CDS. The optimum length of PF inside CPFDS and SF inside CSFDS was 3 mm and 5–10 mm, respectively. Both incorporating PF or SF can effectively improve the ductility of CDS. Based on the proposed parameters of total-water/cement ratio and fiber cementation factor, the effective strength development models of CPFDS and CSFDS considering cement content, fiber content, water content and curing time were empirically established. The fiber “bridge” effect and interfacial friction between fiber and cemented soil particles were mainly responsible for the strength evolution and ductility improvement of CPFDS and CSFDS.

Electrical rock typing using Gaussian mixture model to determine cementation factor

Many studies have worked on the estimation of fluid saturation as an important petrophysical property in hydrocarbon reservoirs. Based on Archie's law, proper determination of cementation factor (m) can lead to accurate values of water saturation. Given that the m is mainly affected by electrical properties of rock, electrical quality index (EQI) can be used to estimate m through a novel rock typing technique. Despite the efficient applicability of EQI for the classification of rocks, with similar electrical behaviors, into distinct electrical rock types (ERTs), manual implementation of this method is time-consuming and gets excessively more difficult for larger datasets. In this work, a fast automated version of EQI methodology was presented. As a fuzzy clustering algorithm, Gaussian mixture model (GMM) was implemented on a large quantity of carbonate and sandstone samples to cluster them into distinct ERTs based on EQI values. To this end, 100 data points were randomly selected for testing purposes, and the remaining data points were used as training subsets for carbonate and sandstone samples. An innovative hybrid EQI-GMM approach was developed to determine the optimum number of clusters. Furthermore, results of two commonly-used criteria, namely Schwarz's Bayesian Criterion (BIC) and Akaike Information Criterion (AIC), showed that they fail to specify ERTs properly. The predicted values for m by the hybrid EQI-GMM approach were more accurate (RMSE is 0.0167 and 0.0056 for carbonate and sandstone samples, respectively) than outputs of the traditional Archie’s law (RMSE is 1.6697 and 0.1850 for carbonate and sandstone samples, respectively).

Cementation factor in clayey rock samples: investigating the role of clay content and determination using electrical rock classification

Accurate determination of cementation factor (m) has a significant role in the petrophysical characterization of underground reservoirs. For clean sandstones, the application of this parameter in Archie's Equation provides a basic framework for estimating water saturation. However, the presence of clay minerals in the rock texture could affect the evaluation process. There are different correlations from which the cementation factor can be estimated. In addition, applying rock classification techniques revealed an excellent prospect for better estimating this parameter. However, in most of the mentioned approaches, the effect of clay minerals is missed. In this study, a newly developed modified form of electrical rock typing technique (i.e. classification of rock samples according to their electrical properties) incorporating the effect of clay minerals for improving the prediction of cementation factor in clay-bearing rocks is proposed. In doing so, a new form of electrical quality index is defined based on which the modified formation resistivity factor versus porosity data for 204 clayey rock samples are classified into nine distinct rock types. Comparative studies demonstrated the priority of the suggested methodology rather than classic hydraulic flow unit-based methods such as flow zone indicator and discrete rock type. The latter showed a high degree of scattering in the classification stage. For each rock type, developed based on the proposed scheme, the equations were proposed in which the modified form of formation resistivity factor and cementation factor versus porosity were correlated. Linear relationships with reasonable values of coefficient of determination were then demonstrated for the developed equations. In addition, the effect of clay minerals on the rock's electrical quality and electrical properties (i.e., rock conductivity and cementation factor) is discussed. The results of this study offer a better framework to incorporate the effect of clay constituents in the prediction of cementation factor, as compared to classical rock typing approaches.

Contribution of Resistivity Properties in Estimating Hydraulic Conductivity in Ciremai Volcanic Deposits

The hydraulic parameters of porous media, such as porosity (φ) and hydraulic conductivity (K), are the most important factors for planning and managing water exploitation from aquifers. This study aims to estimate the hydraulic conductivity parameters using the geoelectric method on volcanic deposits on the northern slope of Mount Ciremai. For this purpose, four data types were used to estimate K and φ, including lithological profiles, water table, groundwater quality, pumping test data, and vertical electrical sounding (VES). Based on Archie's law and Kozeny's equation, we get the alpha (α) values and cementation factor (m) from which the median values of α = 1.01 and m = 1.36 represent the studied aquifer. The porosity (φ) of the aquifer varies from 0.097 to 0.187 with an average of 0.141 and is spatially related to the hydraulic conductivity (kgm), which varies from 4.97 × 10-6 to 6.75 × 10-5 m/s after the application of Kozeny's equation. The hydraulic conductivity (Kp) calculated from the pumping tests varies from 9.07 × 10-6 to 1.06 × 10-4 m/s and is strongly correlated (r = 0.87). Furthermore, a relation between resistivity and hydraulic conductivity was established for the studied aquifer to estimate these parameters in sites lacking data.

Saturation evaluation for fine-grained sediments

Accurate quantification of the gas hydrate content in the deep sea is useful for assessing the resource potential and understanding the role of gas hydrates in the global carbon cycle. Resistivity logging data combined with Archie's equation are often used to calculate gas hydrate saturation, but the reliability is dependent on the rationality of the empirical parameter cementation factor and saturation index. At present, an increasing number of fine-grained hydrate-rich sediment regions have been discovered worldwide through drilling efforts, and the reservoir types and hydrate distribution are diverse, which differs greatly from that of coarse-grained reservoirs of hydrate-bearing sediment. This results in vertical variations in m and n through stratigraphy. At present, the saturation evaluation effect of these reservoirs cannot be improved. In this work, a theory for the determination of the cementation factor and saturation index was first proposed to obtain reliable and variable values of the empirical parameters. Then, a hydrate saturation evaluation technique with variables m and n was formed based on the well logging data. This technique was used to evaluate complex fine-grained hydrate-bearing reservoirs in several regions worldwide. It was found that the highest n could be 16, and the log calculation results were more consistent with the core hydrate saturation. Additionally, the cause of the excessively high n values was explained from physical principles, and the result was verified with actually well log data. In future evaluations of the amount of hydrate resources in fine-grained sediment reservoirs worldwide, new saturation estimation methods should be taken into account to advance hydrate research.

Restriction of Re(VII) and Se(IV) diffusion by barite precipitation in compacted bentonite

The diffusion of anionic radionuclides in bentonite buffers for a high-level radioactive waste repository is only minimally retarded due to the anion exclusion effect and the low sorption onto the bentonite. In this study, barite precipitates in compacted barium-modified bentonite (Ba-bentonite) were used to study the restriction of the diffusion of Re(VII) and Se(IV). To this end, a synthetic porewater containing sulfate was placed in contact with compacted Ba-bentonite so that the sulfate ions could diffuse in the pores and produce barite precipitates. The Ba-bentonite and the bentonite with barium sulfate (BBS) retained the original interlayer structure based on X-ray diffractometer (XRD) analysis. Scanning electron microscopy (SEM) analysis revealed that the barite precipitates were formed in the inter-aggregate pores. A through-diffusion method was employed to measure the effective diffusion coefficient and the rock capacity factor of Re(VII) and Se(IV) in compacted Gaomiaozi (GMZ) bentonite, Ba-bentonite, and BBS. The effective diffusion coefficient decreased with increasing the compacted dry density of the three bentonites, and it decreased with increasing the amount barite precipitates in the BBS. The diffusive flux was completely stopped by the formation of high amounts of barite precipitates. The relationship between the effective diffusion coefficient and the accessible porosity could be described by Archie's law. The cementation factor of BBS was 2.9 for Re(VII) and 3.2 for Se(IV). Compared to the GMZ and Ba-bentonites, the high cementation factor of the BBS indicated a low connectedness and/or a high tortuosity. It had a better clogging effect on anion diffusion than the Ba- and GMZ bentonites.

Petrofacies-Dependent Cementation Factor Relationship for Low-Resistivity Miocene Carbonates: Mumbai Offshore Basin

Summary In Mumbai offshore, Miocene carbonates are deposited with intermediate clastic inputs under cyclic sea level changes and have undergone diagenesis from time to time. Miocene carbonate layers deposited southwest of Mumbai High are producing a good amount of hydrocarbon from 1 to 2 Ω·m resistivity pays. A total of 58 representative core plugs from four different wells were studied to identify the reason for low resistivity and to classify rock facies types and porosity systems using scanning electron microscopy (SEM), thin-section nuclear magnetic resonance (NMR), and petrophysical core data. It was observed from the core study that Miocene carbonates have complex porosity systems and mud-supported to grain-supported reservoir facies. Dominance of mud-supported matrix is the main reason for low resistivity in Miocene carbonate layers as observed from integrated advanced log and core studies. Conventional petrophysical evaluation using constant petrophysical parameters (a, m, n) or linear correlation of cementation factor with porosity can lead to erroneous results in this scenario. A petrofacies-dependent correlation among cementation factor and porosity is attempted in this study for realistic evaluation of low-resistivity carbonate reservoirs. Different cementation factors vs. porosity relations have been derived for various carbonate formations worldwide. Shell formula demonstrates that cementation factor increases with decreasing porosity while correlation derived by Borai and Rafiee brought out inverse relation among cementation factors with porosity in tight carbonates and is providing almost constant cementation factor beyond 0.2. But, in our study, a core porosity-cementation factor plot of reservoir facies is showing that below 0.1, m values are increasing with increase of porosity, which is contradictory to Shell formula. This trend of cementation factor at low porosities is due to the presence of secondary porosity. In the porosity range 0.1–0.25, cementation factor increases eventually with the increase of porosity, but beyond porosity values 0.25, increase in porosity causes decrease of cementation factor. This is due to increasing content of mud-supported matrix, which is overall increasing the total porosity but eventually decreasing cementation in a rock. A new nonlinear correlation has been established between m and porosity for Miocene carbonates of Mumbai offshore area, by incorporating all the factors affecting cementation factor (m). Finally, saturation estimated using variable m either using newly established core derived correlation or resistivity image data is giving representative and improved saturation against low-resistivity reservoir layers compared with constant m.

The Importance Of Litho-Facies Distinction In Determining The Most Representative Cementation Factors For Well-Log Evaluation : An Old Issue Persistently Neglected

Cementation factor is a parameter always required in any conventional open-hole log analysis leading to determination of water saturation. Considering the central of water saturation in the estimation of hydrocarbon in place and reserves, any error in the use of the parameter may prove fatal. A common practice in the oil industry is that acquisition of laboratory-derived cementation factor has never been given a proper attention. It occurs very often that too few samples – hardly represent the rocks of reservoir of concern – are assigned for laboratory test. The practical use of the parameter in the log analysis also often draw question, in which un-representative cementation factor is arbitrarily used due to lack of the data. The effect of this practice has long been known but is often neglected – with all of its consequences – up to present day. This study tries to revive the awareness through presenting a fact that cementation factor may vary due to differences in litho-facies characteristics. Formation resistivity factor data from forty-seven limestone coreplug samples were taken from a West Java (WJ) field. Visual description over the samples has shown that they belong to several litho-facies types. Results of the study have mainly proved that different litho-facies type may have significantly different cementation factors. An averaging effect is also obvious when data from all samples are processed collectively. The effect of improper use of cementation factor is shown through the application of three water saturation models through which erroneous water saturation estimates are produced. The finding of the study is again hoped to reinforce the awareness of the use of proper and representative cementation factor

A Laboratory Approach Considering Salinity to Investigate Archie’s Parameters in Deep Shale: A Case Study in Longmaxi Formation, Southern Sichuan

Archie’s parameters are substantial to be investigated in the evaluation of water saturation. Many researchers adhered to the opinion that Archie’s equation can still be applied to water saturation calculation in shale if the accuracy of relative parameters could be improved. External conditions, such as temperature, confining pressure, water salinity, wettability, and displacement, may influence the determination of Archie’s parameters. The aim of the study is to investigate the effect of salinity on Archie’s parameters and their correlation with mineral composition and pore structure. The mineral contents and petrophysical properties were firstly acquired through X-ray diffraction (XRD) and basic measurements. Rock-electric experiments under different salinity were conducted on deep shale samples taken from Longmaxi (LMX) Formation in Luzhou (LZ). The results indicate that Archie’s parameters of “ a ,” “ b ,” “ m ,” and “ n ” under actual brine salinity are assigned to 1.47, 1, 1.26, and 1.6, respectively. Our cementation factor is lower than that in other studies including (shaly) sandstones, carbonates, and shales, probably due to the extremely low porosity in study area. Salinity has a positive effect on cementation factor ( m ) and saturation exponent ( n ), suggesting the traditional assignment to Archie’s parameters is inappropriate. It was concluded that the complicated pore structure and high porosity mainly associated with clay mineral may trigger the increased cementation factor. Further mathematical derivations confirmed that the rock resistivity is inextricable from pore system and establish a physical model. The paper provides a solid evidence base for further understanding and evaluation of water saturation in unconventional shale reservoirs, more significantly, innovatively unveils the research into Archie formula in deep shale reservoirs of southern Sichuan basin.

Early aseptic loosening of the tibial component at the cement-implant interface in total knee arthroplasty: a narrative overview of potentially associated factors.

Total knee arthroplasty (TKA) is a highly effective surgical procedure, but in some patients TKAs fail early due to a variety of underlying factors. About 11% of revision TKAs within one year of primary TKA are the result of aseptic loosening of the tibial component at the cement-implant interface. Literature regarding the most important factors associated with this type of loosening is scarce. The objective is to give an overview of the literature regarding factors associated with aseptic loosening of the tibia component at the cement-implant interface in total knee arthroplasty. A narrative literature review based on publications identified through PubMed and CINAHL databases. Twelve studies were identified, which describe a total of 299 cases of early aseptic loosening of the tibia component at the cement-implant interface. The main associated factors reported were cementa- tion factors. These factors included the use of high viscosity cement (HVC), cement application methods and cement thickness. Other main reported associated factor related to implant design factors, which included component shape and surface roughness. The least frequently reported associated factors related to the patient characteristics of body mass index (BMI). Several factors associated with early aseptic loosening of the tibial component at the cement-implant interface in total knee arthroplasty were identified in this review. The most frequently reported associated factors related to cementation factors and implant design factors. Because the literature in this area is scarce, further research is warranted in an effort to prevent early aseptic loosening in future TKAs.

Evaluating cementation factor for bioturbated sandstones, Bhuj Formation, Kachchh Basin, India: a novel approach using triple-porosity model

Cementation factor has a crucial role in evaluating volumetric reserves for heterogeneous clastic reservoir. Bioturbation is a prominent source of heterogeneity existing in hydrocarbon-bearing formation across the world. The effect of bioturbation on the petrophysical properties of the clastic has not been comprehensively understood yet, especially its effect on cementation factor estimation. The precise description of such properties is beneficial in developing better volumetric estimates and optimizing field development planning. The present work discusses an approach to characterize cementation factor in bioturbated clastic Bhuj Formation, Kachchh Basin, India. In order to ascertain the cementation exponent for bioturbated media, an improved triple-porosity model is proposed by quantifying the total porous volume into three components, namely matrix 1, matrix 2 and bioturbated region. An equivalent resistance model is then developed by identifying the series and parallel relation between the two matrix components and the burrow. The experimental observations of electrical response indicated large variation in resistivity in vertical cores compared to horizontal cores. The decreased resistivity is due to the vertically aligned burrow which due to their enhanced porosity provides less tortuous path for current to flow. The triple-porosity model is validated with different porosity value of matrix 1, matrix 2 and burrow, and a cementation factor of 2.8 for higher bioturbated samples and 3 for lower bioturbated samples is obtained. This validates the previous understanding of enhanced flow and storage property and thereby produces a consistent way to evaluate total cementation factor. The correct estimation of cementation factor helps in precise evaluation of water saturation in bioturbated reservoirs.

Application of electrical rock typing for quantification of pore network geometry and cementation factor assessment

Rock typing with its various applications reduces the required time and cost for petrophysical analysis by categorizing similar rocks into distinct groups. Rock typing is divided into different categories, one of which, is electrical rock typing. An application of static electrical rock typing is cementation factor prediction which significantly affects fluid saturation estimation. Many factors, such as pore geometry, affect cementation factor in various means. Hence, achieving an explicit correlation to compute it as a function of these affecting factors is difficult. However, examining petrophysical properties which influence cementation factor is feasible. In this study, two definitions of formation resistivity factor are merged to achieve the cementation factor correlation as a function of effective cross-sectional area, porosity, and electrical tortuosity. To determine effective cross-sectional area and electrical tortuosity in wellbore through a time-efficient and inexpensive method, electrical rock typing is used. The results of this study reveal that Kozeny's factor is perfectly correlated with effective cross-sectional area and electrical tortuosity. Therefore, effective cross-sectional area and electrical tortuosity are computed throughout the wellbore. Moreover, investigating the relation between flowing porosity and rock capacity for transmitting electricity shows that they are directly related. Cementation factor and stagnant porosity also have a direct relationship. The findings of this study aid the assessment of porous media for attaining a clear understanding of petrophysical properties relationships, and their impact on porous media capability for storing and transferring fluid and transmitting electricity. Determining petrophysical properties continuously in wellbore leads to a better comparison between different segments of the reservoir. Regarding the fact that all presented methods are mainly based on log responses, they are easy to apply. However, the availability of enough samples is essential to initiate the analysis. • Obtaining effective cross-sectional area continuously through wellbore. • Developing a method to determine electrical tortuosity through wellbore. • High EQI Samples have a higher flowing porosity, and a lower cementation factor. • As electrical tortuosity increases, m rises due to reduction in flowing porosity.