Poor Cement Research Articles

Impact of excavation footage on vertical shaft lining deformation and surrounding rock stress in Xiyu conglomerate

The Xiyu conglomerate, which is extensively distributed in Xinjiang, China, presents challenges for vertical shaft construction owing to its poor cementation and low strength. The selection of an appropriate footage length is paramount for ensuring safe construction. Based on the shaft pipeline construction project of the Xinlongkou Hydropower Station on the Kuitun River, this study investigated the impact of footage length on the stability of vertical shafts within the Xiyu conglomerate strata using finite element simulation and measurement data to analyze the lining displacement and change in stress in the surrounding rock. The results show that the excavation footage has little effect on the lining’s horizontal displacement during vertical shaft excavation. A mathematical model was developed to describe how the vertical displacement of the lining varies with the excavation footage and vertical shaft depth. Below a critical threshold, the stress in the surrounding rock cannot be effectively alleviated, leading to a concentration of stress; above that critical threshold, an excessively large excavation increases the load on the surrounding rock. Based on the simulation results and factors such as economic benefits, construction speed, and safety, an excavation footage of 4 m is judged to be appropriate.

Mechanical property testing and damage assessment of the regenerated rock mass with very weakly bonded cement

The regenerated rock mass is a bearing structure formed by natural compaction in a hollow area, and the investigation of its optimal consolidation material and consolidation parameters is the key to improving the supporting effect and bearing stability of roadways. The effects of consolidation materials and parameters on the stability of the regenerative rock mass were studied using laboratory tests, numerical simulations, and theoretical analyses. Acoustic emission was used to monitor the variation characteristics of energy and ringing count during the process of rock mass failure, and the bonding interface area of the extremely weak cementation regeneration structure was tested by electron microscope scanning. The results show that there is a quadratic function relationship between the water–cement ratio of different cementing materials and the bond strength of the recycled rock mass; the regenerative rock mass with superfine cement exhibited the highest compressive strength and the largest cumulative energy of acoustic emission. This shows that it has the strongest bearing capacity, the highest elastic performance, the most stable micro-fracture development, and the best cementation effect, followed by ordinary cement, gypsum, and laterite. The scanning test showed that the regenerated structure had more internal pores, a loose structure, and poor cementation. Three-dimensional scanning modeling of four representative broken rock blocks was carried out, and the simulation verified that the regenerated structure had macroscopic “X”-shaped shear failure characteristics. The numerical simulation also verified three forms of rupture in the regenerative structure detected by electron microscopy scanning. Exploring the mechanism of action of the regenerative rock mass in the goaf provides a certain reference value for the stability control of the regenerated rock mass roadway.

Total Femur Replacement as a Salvage Procedure for Failed Distal Femur Megaprosthesis: A Case Report and Literature Reviews

Abstract Total femoral replacement (TFR) is not a common surgery and most indications are for oncological pathologies. However, there are few instances where non-oncological indications might necessitate TFR; this may be a salvage surgery for failed previous hip and/or knee surgeries with consequent significant femur bone loss. We present a 59-year-old obese woman with right thigh pain and difficulty with walking of 5 years duration. She had undergone bilateral total knee replacement 10 years earlier on account of severe knee osteoarthritis. She had a fall 3 years prior to presentation and sustained a periprosthetic fracture around the right knee which was managed with a fixed angle blade plate and screws. This was complicated by implant breakage and non-union. She subsequently had implant removal and a right distal femur replacement (DFR) surgery 2 years prior to presentation. A year after the DFR surgery, she began to experience “start-up” pain, instability around the knee and difficulty with walking without support. A clinical and radiologic diagnosis of aseptic loosening of the distal femur megaprosthesis was made and she was offered a revision DFR surgery which also failed due to poor cementing technique, bone loss at the proximal femur, and severe osteoporosis. Patient ended up with a right total femur replacement to salvage the limb. She had improved Lower Extremity Functional Score of 27 after 12-month follow-up. TFR is a viable salvage procedure for severely compromised femur and/or significant bone loss from multiple non-oncological surgeries of the femur.

Study on the properties improvement of wet quarry sludge made artificial aggregates by using PAM and CaO

The artificial aggregates prepared with high crystalline wet quarry sludge (WQS) by cold-bonded process suffer from low mechanical strength and poor solidification effect. Inspired by the shell, polymer chains were incorporated to enhance the connection among WQS particles. However, traditional polymer modification faces many limitations such as high cost and hydration inhibition. In this work, calcium oxide (CaO) and polyacrylamide (PAM) were co-used to address the above limitations and improve the properties of artificial aggregates. The compressive strength, hydration products and microstructure of modified WQS-aggregates were monitored. The main findings prove that the co-use of CaO and PAM effectively improves the mechanical performance of WQS-aggregates. The compressive strength of aggregates modified by CaO and PAM reach 11.85 MPa, exceeding the control by approximately 46.3 %. This approach mitigates issues like crack generation and poor cement hydration, which will occur when they are added separately. Through metal coordination and promoted carbonation behaviors, the introduction of CaO and PAM promotes the formation of a 3D organic-inorganic network and induces a denser microstructure. The porosities of aggregates reduce from 27.48 % to 24.83 %. The incorporation of CaO and PAM enhances the solidification of heavy metals. The prepared WQS-aggregates meet the requirements of environmental security. It is believed that this work will provide a new solution for the preparation of low carbon artificial construction products with low activity solid wastes.

Prediction of emergency-free operation of production wells with a horizontal termination under conditions of high removal of mechanical impurities on the example of the Severo-Komsomolskoe field

Relevance. As readily available oil reserves are developed and production technologies develop, oil and gas companies are gradually moving to the development of previously unprofitable assets. Over the past five years, several oil-and-gas condensate fields with oil rims have been put into operation in Western Siberia. Their development is further complicated by oil high viscosity and poor cementation of the reservoir rocks. Low values of critical drawdown do not allow oil to be produced without destruction of the productive formation, and mechanical impurities entering the well lead to spillage of perforation intervals and downhole equipment failures. The use of mathematical modeling in relation to the operation of wells in the conditions of the removal of mechanical impurities will make it possible to control production and select the optimal well operation mode. Aim. Forecasting the trouble-free operation of a production well under conditions of high removal of mechanical impurities. Objects. Producing oil wells; the subject of the study is the movement of solid particles in the wellbore of a production well, the relationship and dependence of formation of sand plugs on the operating parameters of the well. Methods. Theoretical research methods – analysis (analysis of models for calculating the critical flow velocity in a horizontal pipe (calculation of the critical velocity in a single-phase flow; calculation of the critical velocity in a multi-phase flow; calculation of the critical velocity based on the balance of forces)) and modeling (simulation of work wells with the removal of mechanical impurities). The totality and combination of these methods are adequate to the goals and objectives, the object and subject of the study of this work. Results. The problem of sand production is typical not only for fields that are in the late stages of development, but also for fields that have recently been put into operation. Sand shows up are a complicating factor in the operation of wells at the Severo-Komsomolskoe high-viscosity oil field located in Western Siberia. The main object of development of the studied field is a weakly cemented sandy layer. Oil production in such difficult areas requires a very careful approach to the choice of development system, to the selection of methods to deal with complications, including the choice of the right method to limit sanding. However, regardless of the approach taken to solve the problem of sand production, some rock will still flow into the well. To prevent the formation of sand plugs, it is necessary to understand the nature of the movement of solid particles along the wellbore. It is possible to assess whether a well is capable of carrying out solid particles from a horizontal section using modeling in specialized software products. Modeling of the well operation, taking into account the influence of mechanical impurities, made it possible to solve the following problems: 1) determine the fluid to carry rock particles out of the horizontal section; 2) identify the areas in which there is a risk of sand plugs; 3) present the dependence for calculating the critical speed for high-viscosity oil with different water cut; 4) assess how the water cut and gas factor affect well operation in conditions of high removal of mechanical impurities; 5) calculate the time of formation of sand plugs.

Microstructure and quantitative tracing of carbonate for calcareous root tubes in dune soil from the Tengger Desert of Northwestern China: Implications for its formation age and paleoenvironmental reconstruction

Calcareous root tubes (CRTs), which are formed by the encrustation of roots with pedogenic carbonate, serve as an archive for paleoclimate reconstructions. However, controversies remain regarding the formation age of CRT carbonate and the quantitative tracing of its sources in the hinterland of the desert. In this study, 13 CRT samples were obtained from 11 sites in the Tengger Desert of northwestern China. Samples were described using X-ray micro-tomography Scanning (Micro-CT), and their 14C ages, δ13C, and 87Sr/86Sr values were measured. The results show that more than 99.84 % of pore diameters in the precipitated carbonate layer were less than 1 mm, which was much smaller than the plant roots in this region. Moreover, the root residues from poor cementation CRTs were dated at 151 − 431 cal yr BP, which was significantly younger than the carbonate age of other complete cemented CRT. Thus, most of the root residues found within completely cemented CRTs may invade after the CRTs formation and their 14C ages cannot represent the CRTs formation period, while the carbonate 14C dating results can indicate the CRTs formation period. 87Sr/86Sr values of CRTs occurred at 0.71152 − 0.71189, indicating that the main source of calcium in CRTs was the dissolution of carbonate in rhizosphere soil. δ13C values of CRTs varied between −5.4 ‰ and −3.2 ‰. Using the end-member mixing model, carbon sources from CRTs can be divided into rhizosphere soil respiration CO2 (81 − 82 %) and atmospheric CO2 (18 − 19 %). Hence, δ13C values of CRTs may derive the δ13C signal from soil and record paleoenvironment conditions. This study enhances our understanding of the formation mechanism of pedogenic carbonate and provides an important aspect in assisting paleoenvironmental reconstructions.

Construction of a nomogram to predict the probability of new vertebral compression fractures after vertebral augmentation of osteoporotic vertebral compression fractures: a retrospective study.

This study aimed to develop and validate a new nomogram model that can predict new vertebral fractures after surgery for osteoporotic compression fractures to optimize surgical plans and reduce the incidence of new vertebral compression fractures. 420 patients with osteoporotic vertebral compression fractures were randomly sampled using a computer at a fixed ratio; 80% of the patients were assigned to the training set, while the remaining 20% were assigned to the validation set. The least absolute shrinkage and selection operator (LASSO) regression method was applied to screen the factors influencing refracture and construct a predictive model using multivariate logistic regression analysis. The results of the multivariate logistic regression analysis showed a significant correlation between bone cement leakage, poor cement dispersion, the presence of fractures in the endplate, and refractures. The receiver operating characteristic curve (ROC) results showed that the area under the ROC curve (AUC) of the training set was 0.974 and the AUC of the validation set was 0.965, which proves that this prediction model has a good predictive ability. The brier score for the training set and validation set are 0.043 and 0.070, respectively, indicating that the model has high accuracy. Moreover, the calibration curve showed a good fit with minimal deviation, demonstrating the model's high discriminant ability and excellent fit. The decision curve indicated that the nomogram had positive predictive ability, indicating its potential as a practical clinical tool. Cement leakage, poor cement dispersion, and presence of fractures in the endplate are selected through LASSO and multivariate logistic regressions and included in the model development to establish a nomogram. This simple prediction model can support medical decision-making and maybe feasible for clinical practice.

Analysis of Factors Influencing the Stability of Submarine Hydrate-Bearing Slopes during Depressurization Production

Natural gas hydrate reservoirs, with shallow burial, poor cementation, and low strength, are prone to submarine landslides triggered by hydrate decomposition during extraction. Prior studies have inadequately considered factors such as the dynamic decomposition of hydrates during depressurization, and its impacts on the reservoir’s geomechanical properties. In this paper, a coupled thermal–hydraulic–mechanical–chemical mathematical model of hydrate decomposition is proposed, and the dynamic geomechanical response and the effect of hydrate decomposition on seafloor settlement and slope destabilization during the process of depressurization mining are analyzed by combining the strength discount method with the example of a hydrate-bearing seafloor slope in the Shenhu area. Furthermore, the study employs an orthogonal experimental design along with range and variance analysis to gauge the impact of critical factors (degree of hydrate decomposition, seawater depth, hydrate reservoir burial depth, hydrate reservoir thickness, and slope angle) on slope stability. The findings suggest that hydrate decomposition is non-uniform and is influenced by stratigraphic temperature gradients and gravity. In the region where hydrate decomposition occurs, the decrease of pore pressure leads to the increase of effective stress. Additionally, the decomposition of hydrates decreases the shear modulus of sediments, leading to deformation and reduced permeability in the affected area. Over a three-year period of depressurization mining, the significantly reduced safety factor increases the risk of landslides. Various factors play a role in the control of submarine slope stability, with slope inclination being the primary factor, followed by the degree of hydrate decomposition, reservoir thickness, burial depth, and seawater depth. Among these factors, hydrate burial depth and seawater depth have a positive correlation with submarine slope stability, while increases in other factors generally decrease stability. These research findings have important implications for the safe exploitation of slopes that contain hydrates.

Evaluation of the casing strength reliability in deep gas well by taking into account the cement quality and strength uncertainty: Method, analysis and application

Casing damage is one of the most challenging engineering issues in deep gas wells, leading to significant economic losses and severe incidents such as gas leaks or high annular pressure. According to field data analysis, in addition to traditional factors like stress, temperature, or corrosion, cement sheath quality also impacts casing damage. Hence, this paper establishes a three-dimensional finite element model for casing-cement sheath -formation considering cement sheath quality. It discusses the impact of different cement sheath defects (such as void and eccentricity) on casing stress distribution under the influence of in-situ stresses, high-pressure fluids, and annular pressure. The analysis reveals that under adverse conditions, poor cement sheath quality exacerbates stress on the casing, increasing the risk of casing failure, with the degree of impact being cement void angle > cement eccentricity > cement void thickness. Based on this, a nonlinear fitting of changes in casing equivalent stress is conducted to establish a model for calculating casing external loads under cement void or eccentricity conditions. Considering the dual uncertainty of casing external load and strength parameters, a casing reliability evaluation method is established based on the external load calculation model and stress-strength interference theory. The reliability of casing strength is assessed and analyzed using a practical well in an oil field as an example. The results indicate that compared to traditional safety factor methods, the reliability evaluation method established in this paper can more intuitively and accurately display variations in casing reliability, offering a scientific basis for optimized design solutions. Optimizing cement sheath performance (such as reduced cement elastic modulus and Poisson's ratio) and enhancing cementing quality (by preventing cement voids and eccentricity) effectively reduce the risk of casing failure.

Development and validation of a nomogram for predicting new vertebral compression fractures after percutaneous kyphoplasty in postmenopausal patients

BackgroundPostmenopausal women face a heightened risk of developing new vertebral compression fractures (NVCFs) following percutaneous kyphoplasty (PKP) for osteoporotic vertebral compression fractures (OVCFs). This study aimed to develop and validate a visual nomogram model capable of accurately predicting NVCF occurrence post-PKP to optimize treatment strategies and minimize occurrence.MethodsThis retrospective study included postmenopausal women diagnosed with OVCF who underwent PKP at the Affiliated Hospital of Shandong University of Traditional Chinese Medicine between January 2016 and January 2021. Patient data, including basic information, surgical details, imaging records, and laboratory findings, were collected. The patients were categorized into two groups based on NVCF occurrence within 2 years post-PKP: the NVCF group and the non-NVCF group. Following the utilization of least absolute shrinkage and selection operator (LASSO) regression for feature selection, a nomogram was constructed. Model differentiation, calibration, and clinical applicability were evaluated using receiver operating characteristic (ROC), calibration, and decision (DCA) curve analyses.ResultsIn total, 357 patients were included in the study. LASSO regression analysis indicated that cement leakage, poor cement diffusion, and endplate fracture were independent predictors of NVCF. The nomogram demonstrated excellent predictive accuracy and clinical applicability.ConclusionsThis study used LASSO regression to identify three independent predictors of NVCF and developed a predictive model that could effectively predict NVCF occurrence in postmenopausal women. This simple prediction model can support medical decision-making and is feasible for clinical practice.

Cementing Techniques In Knee Surgery (CeTIKS).

Aseptic loosening is the most common cause of failure following cemented total knee arthroplasty (TKA), and has been linked to poor cementation technique. We aimed to develop a consensus on the optimal technique for component cementation in TKA. A UK-based, three-round, online modified Delphi Expert Consensus Study was completed focusing on cementation technique in TKA. Experts were identified as having a minimum of five years' consultant experience in the NHS and fulfilling any one of the following criteria: a 'high volume' knee arthroplasty practice (> 150 TKAs per annum) as identified from the National joint Registry of England, Wales, Northern Ireland and the Isle of Man; a senior author of at least five peer reviewed articles related to TKA in the previous five years; a surgeon who is named trainer for a post-certificate of comletion of training fellowship in TKA. In total, 81 experts (round 1) and 80 experts (round 2 and 3) completed the Delphi Study. Four domains with a total of 24 statements were identified. 100% consensus was reached within the cement preparation, pressurization, and cement curing domains. 90% consensus was reached within the cement application domain. Consensus was not reached with only one statement regarding the handling of cement during initial application to the tibial and/or femoral bone surfaces. The Cementing Techniques In Knee Surgery (CeTIKS) Delphi consensus study presents comprehensive recommendations on the optimal technique for component cementing in TKA. Expert opinion has a place in the hierarchy of evidence and, until better evidence is available these recommendations should be considered when cementing a TKA.

Effects of several polymeric materials on the improvement of the sandy soil under rainfall simulation

Poor cementation between soil particles is a fundamental cause of soil erosion and desertification. In recent decades, many polymers have been used to cement soil particles and improve the physical and chemical properties of soils. The contributions of polymers with different structures and functional groups to soil improvement vary considerably. In this study, a mixture comprising polyacrylamide (PAM), sodium polyacrylate (PAAS), hydroxypropyl methylcellulose (HPMC), and polyvinyl alcohol (PVA) was investigated to meet the requirements of soil water retention, erosion resistance, and plant growth. The results showed that the time required for the modified soil to reach drought conditions was extended by 4–7 days. The PAM/HPMC, PAM/PVA and PAM/PAAS experimental groups reduced the erosion rate by 99.57%, 98.3% and 96.38%, respectively, compared to that of the control group. The belowground plant biomass was significantly increased by PAM/HPMC, PAM/PAAS, and PAM/PVA, with increases of 115.92%, 145.23%, and 205.67%, respectively. HPMC contributed more to the soil erosion resistance and water-holding capacity, PAAS improved the soil porosity substantially, and PVA significantly increased the plant biomass. The rigid structures of the polymer chains enhanced the structural stability of the soil, and the hydrophilic functional groups increased the hydrophilicity of the amended soil. This study indicates different polymers that may be used to improve soil properties.

MODELLING THE EFFECT OF CONTAMINATION ON THE RHEOLOGICAL PROPERTIES OF CEMENT SLURRY USING OIL-BASED MUD AS CONTAMINANT, TO IMPROVE CEMENTING JOB DESIGN AND EXECUTION IN THE OIL & GAS INDUSTRY

Cementing job failure often occurs due to cement slurry contamination with drilling mud during primary cementing and remedial cementing jobs in the oil & gas industry. The enormous consequences of cement slurry contamination with drilling mud include drastic reduction in the thickening time of cement slurry and increased rheological properties of the cement slurry due to the much more viscous resultant cement slurry/mud mixture often leading to incomplete cement job, poor mud removal, poor cement bond, gas channeling, gas kick, blow out, downtime, revenue loss and remedial cementing. The rheological properties of cement slurry and drilling mud are strongly dependent on temperature. There are also emergency situations in the oilfield where bottomhole temperature changes to a higher temperature requiring adjustments in the original cementing job design to include the new bottomhole temperature when Laboratory services are not immediately available. The aforesaid and the associated cost of remedial operations prompted this work to investigate the effect of temperature and contamination on the rheological properties of cement slurry using oil-based mud as contaminant to invent a process to better avoid cement slurry contamination and to improve cementing job designs and execution in the oil & gas industry. The methods applied include Laboratory testing and mathematical modeling. Mathematical models were developed using Microsoft Excel to predict the rheological properties of contaminated cement slurries as a function of temperature and contamination with oil-based mud as the contaminant. Results showed that the Plastic viscosity and yield stress of the contaminated cement slurries increased with temperature and extent of contamination with oil-based mud but the yield stress also decreased with extent of contamination at high temperatures. The very high regression coefficient obtained with each of the mathematical models showed that the mathematical models can be confidently applied to predict the rheological properties (Plastic viscosity and yield stress) of the contaminated cement slurries as a function of temperature and extent of contamination with the oil-based mud.

CEMENTING TECHNIQUES IN KNEE SURGERY (CETIKS): A UK EXPERT CONSENSUS STUDY

AbstractIntroductionAseptic loosening is the most common cause of failure following cemented total knee arthroplasty (TKA) and this has been linked to poor cementation technique. We aimed to develop a consensus on the optimal technique for component cementation in TKA.MethodologyA UK based, three round, online modified Delphi Expert Consensus Study was completed focussing on cementation technique in TKA. Experts were identified as having a minimum of 5 years Consultant experience in the NHS and fulfilling any one of the following three criteria:· A ‘high volume’ knee arthroplasty practice (>150 TKA per annum) as identified from the National joint registry (NJR).· A senior author of at least 5 peer reviewed articles related to TKA in the previous 5 years· A named trainer for a post CCT fellowship in TKA.ResultsEighty-one experts (Round 1) and eighty experts (Round 2 and 3) completed the Delphi Study. Four domains with a total of twenty-four statements were identified. 100% consensus was reached within the cement preparation, pressurisation, and cement curing domains. 90% consensus was reached within the cement application domain. Consensus was not reached with only one statement regarding the handling of cement during initial application to the tibial and/or femoral bone surfacesConclusionThe CeTIKS expert consensus study presents comprehensive recommendations on the optimal technique for component cementation in TKA. Expert opinion has a place in the hierarchy of evidence and until better evidence is available these recommendations should be considered when cementing a TKA.

Stability analysis and deformation control method of swelling soft rock roadway adjacent to chambers

The surrounding rock of swelling soft rock roadway has high clay mineral content, strong expansibility after encountering water, low strength and poor cementation. The roadway is prone to large deformation under the influence of complex geostress. Combined with the support change of the development roadway of 2# coal in Hongqingliang mine, through geological survey, field observation and indoor test, the failure mechanism of the traditional support method of “anchor bolt + anchor cable + anchor mesh + shotcrete” was revealed by the adjustment of the surrounding rock stress after the excavation and support of the adjacent chambers. The research results show that the surrounding rock stress will cross the adjacent chambers and form a concentrated area near the weakly cemented roadway, and the maximum stress increase ratio of surrounding rock within the stress concentration range will reach 50%. The farther the chambers are from the weakly cemented roadway, the smaller the range of the surrounding rock stress concentration area. When the distance exceeds about 12 times the average height of the chambers, the surrounding rock stress concentration tends to disappear. Based on the fully enclosed combined support method of the "U-shaped steel sheds closure roof and sides + filling flexible material behind the sheds + laying reinforcement mesh and concrete in floor + strengthening key parts", the construction process flow applicable to the working condition of swelling soft rock roadway is formulated.

Research on the Fracture Propagation Law of Separate Layered Fracturing in Unconventional Sandstone Reservoirs

The unconsolidated sandstone is a type of rock that has poor cementation, a low strength, a high porosity, and permeability. It is highly compressible under high stress and exhibits non-linear plastic deformation during hydraulic fracturing construction in its reservoir. In this study, the mechanical properties of unconsolidated sandstone with a different permeability were studied, and a three-dimensional hydraulic fracture propagation numerical model was established based on the modified traditional Cambridge model. This model was used to simulate the fracture propagation law of unconsolidated sandstone in separate layer fracturing under different construction conditions. During hydraulic fracturing construction, the fracturing fluid slowly invades the reservoir when the displacement of the fracturing fluid is small. The unconsolidated sandstone undergoes compaction and hardening, followed by shear expansion, and then complete destruction. A larger displacement will cause the reservoir rock to directly enter the state of destruction from compaction and hardening. This study found that several critical parameters are obtained for fracturing construction. When the displacement is greater than 5 m3/min, the fracturing fluid exceeds 100 mPa·s, or when the filtration coefficient exceeds 1.2 × 10−3 m/s, the second and third layers will be penetrated. This study provides valuable insights into the mechanical properties of unconsolidated sandstone and reveals the critical parameters for the successful hydraulic fracturing construction in this type of reservoir.

A Novel Efficient Borehole Cleaning Model for Optimizing Drilling Performance in Real Time

The drilling industry has evolved significantly over the years, with new technologies making the process more efficient and effective. One of the most crucial issues of drilling is borehole cleaning, which entails removing drill cuttings and keeping the borehole clean. Inadequate borehole cleaning can lead to drilling problems such as stuck pipes, poor cementing, and formation damage. Real-time drilling evaluation has seen significant improvements, allowing drilling engineers to monitor the drilling process and make adjustments accordingly. This paper introduces a novel real-time borehole cleaning performance evaluation model based on the transport index (TIm). The novel TIm model offers a real-time indication of borehole cleaning efficiency. The novel model was field-tested and validated for three wells, demonstrating its ability to determine borehole cleaning efficiency in typical drilling operations. Using TIm in Well-A led to a 56% increase in the rate of penetration (ROP) and a 44% reduction in torque. Moreover, the efficient borehole cleaning obtained through the use of TIm played a significant role in improving drilling efficiency and preventing stuck pipes incidents. The TIm model was also able to identify borehole cleaning efficiency during a stuck pipe issue, highlighting its potential use as a tool for optimizing drilling performance.

Fracture Propagation Mechanism of Tight Conglomerate Reservoirs in Mahu Sag

Conglomerate reservoirs are usually formed in sag slope belts, which have the characteristics of near-source rapid deposition, rapid sedimentary facies change, and distinct reservoir heterogeneity. Therefore, it is difficult to carry out treatments of stimulation because of insufficient understanding of the propagation mechanism of the unique “gravel-bypassing” and “gravel-penetrating” characteristics of fracture morphologies in Mahu conglomerate reservoirs. In order to study the law of hydraulic fracture propagation in conglomerate reservoirs, based on Brazilian splitting test results for conglomerates with different gravel particle sizes and different cementation degrees, true tri-axial fracturing experiments conducted in the laboratory were performed to conduct experimental research on natural conglomerate outcrops and analyze the effects of gravel size, fracturing fluid viscosity, and pumping rate on hydraulic fracture propagation morphology. The results show that: (1) the gravel cementation strength of fracture pressure is higher and the pressure drops preferably after fracturing. The fracture is more inclined to “pass through the gravel” to propagate in large-particle-size gravel. The poor gravel cementation of fracture pressure is relatively low-level and the pressure after fracture drops slightly, and fractures tend to occur at the margin of gravel; (2) using slick water for fracturing tends to initiate and propagate fractures at multiple points on the wellbore, which is conducive to the formation of complex fracture networks and the improvement of volume stimulation effects. Guanidine-gum fracturing has a higher fracture-forming efficiency and higher net pressure; and (3) a low pumping rate will increase the interaction degree between fractures and gravel, and gravels will cause a change in fracture roughness, resulting in small local fracture widths.

A Novel Model for the Real-Time Evaluation of Hole-Cleaning Conditions with Case Studies

The main challenge in deviated and horizontal well drilling is hole cleaning, which involves the removal of drill cuttings and maintaining a clean borehole. Insufficient hole cleaning can lead to issues such as stuck pipe incidents, lost circulation, slow rate of penetration (ROP), difficult tripping operations, poor cementing, and formation damage. Insufficient advancements in real-time drilling evaluation for complex wells can also lead to drilling troubles and an increase in drilling costs. Therefore, this study aimed to develop a model for the hole-cleaning index (HCI) that could be integrated into drilling operations to provide an automated and real-time evaluation of deviated- and horizontal-drilling hole cleaning based on hydraulic and mechanical drilling parameters and drilling fluid rheological properties. This HCI model was validated and tested in the field in 3 wells, as it was applied when drilling 12.25″ intermediate directional sections and an 8.5″ liner directional section. The integration of the HCI in Well-A and Well-B helped achieve much better well drilling performance (50% ROP enhancement) and mitigate potential problems such as pipe sticking due to hole cleaning and the slower rate of penetration. Moreover, the HCI model was also able to identify hole-cleaning efficiency during a stuck pipe issue in Well-C, which highlights its potential usage as a real-time model for optimizing drilling performance and demonstrates its versatility.

A Comparative Study: Effects of Fineness of Cement on Consistency and Compressive Strength of Different Branded Cement in Pakistan

Abstract Cement is one of the key components of concrete, and the qualities of a particular type of cement will affect the attributes of concrete made with that cement. The influence of variations in cement brand attributes that are available in Pakistan is examined in this study. Poor cement choice may affect how long a concrete building project will last. Fineness, cement consistency, concrete compressive strength, and mortar cube strength all grow with cement fineness since they all have a positive relationship with each other. This study aimed to investigate a few particular mechanical and physical characteristics of eight cement brands used in Punjab, Pakistan. The brands of cement that were compared were Kohat, Askari, Bestway, Paidaar, DG, Pioneer, Flying, and Fauji cement. The testing was carried out in a lab and according to ASTM guidelines. In contrast, Kohat had 5.17%, Askari had 8.67%, Bestway had 3%, DG had 2.67, Flying had 9.67, and Fauji cement had 6.33%, with only Paidaar above the allowed limits. Kohat and Paidaar cement's typical consistency was 30%, DG cement was 26%, and Bestway cement was 26%; all of them fell within the range of (26%- 33%). The 28-day compressive strength test results for DG cement and Bestway cement were 7787.74 Psi and 7225.17 Psi, respectively. The strength of Pioneer and Flying cement was found to be lower than that of other cement brands. Except for DG and Bestway cement, all eight brands of cement are used for all structural elements. Bestway cement is much superior for high-rise structures and heavy structural members. Consequently, by comparing the trace element concentration of various brands of Portland cement in Pakistan, the study evaluates the impact of trace element content on cement quality and concrete strength.