Pressure Ramp Research Articles

Analysis of a brake squeal functional model using a linear parameter varying perspective

Brake squeal is a limit cycle vibration induced by mode coupling instability that depends on operating conditions such as applied pressure, temperature, and disc velocity. This work proposes a simplified functional model of brake squeal that reproduces the main characteristics observed in a full-scale industrial test campaign: vibration growth, limit cycle saturation, vibration decay and parametric dependence. The proposed functional model differs from the well-known Hoffmann model by the introduction of a nonlinear contact law and a quasi-static pressure loading. First, using a harmonic balance perspective, non-linear forces are shown to lead to a pressure and amplitude dependent contact stiffness. This Linear Parameter Varying perspective allows complex mode computations in the pressure/amplitude domain which are then correlated with a series of transient responses of the nonlinear modes for three different pressure profiles. The chosen profiles represent usual experiments: drag where a constant pressure is applied, pressure ramps and pressure oscillations mimicking the effect of wheel spin on the contact surfaces.

Induction of subject-ventilator asynchrony by variation of respiratory parameters in a lung injury model in pigs

BackgroundSubject-ventilator asynchrony (SVA) was shown to be associated with negative clinical outcomes. To elucidate pathophysiology pathways and effects of SVA on lung tissue histology a reproducible animal model of artificially induced asynchrony was developed and evaluated.MethodsAlterations in ventilator parameters were used to induce the three main types of asynchrony: ineffective efforts (IE), auto-triggering (AT), and double-triggering (DT). Airway flow and pressure, as well as oesophageal pressure waveforms, were recorded, asynchrony cycles were manually classified and the asynchrony index (AIX) was calculated. Bench tests were conducted on an active lung simulator with ventilator settings altered cycle by cycle. The developed algorithm was evaluated in three pilot experiments and a study in pigs ventilated for twelve hours with AIX = 25%.ResultsIE and AT were induced reliably and fail-safe by end-expiratory hold and adjustment of respiratory rate, respectively. DT was provoked using airway pressure ramp prolongation, however not controlled specifically in the pilots. In the subsequent study, an AIX = 28.8% [24.0%-34.4%] was induced and maintained over twelve hours.ConclusionsThe method allows to reproducibly induce and maintain three clinically relevant types of SVA observed in ventilated patients and may thus serve as a useful tool for future investigations on cellular and inflammatory effects of asynchrony.

A platform for planar dynamic compression of crystalline hydrogen toward the terapascal regime

We describe a method for laser-driven planar compression of crystalline hydrogen that starts with a sample of solid para-hydrogen (even-valued rotational quantum number j) having an entropy of 0.06 kB/molecule at 10 K and 2 atm, with Boltzmann constant kB. Starting with this low-entropy state, the sample is compressed using a small initial shock (<0.2 GPa), followed by a pressure ramp that approaches isentropic loading as the sample is taken to hundreds of GPa. Planar loading allows for quantitative compression measurements; the objective of our low-entropy compression is to keep the sample cold enough to characterize crystalline hydrogen toward the terapascal range.

Effect of electrochemical charging on the hydrogen embrittlement susceptibility of a low-alloyed tempered martensitic steel submitted to high internal pressure

The influence of hydrogen on the mechanical behavior of a quenched and tempered 42CrMo4 steel has been evaluated by means of high internal pressure fracture tests carried out on hydrogen precharged notched cylindrical specimens. The notched cylindrical specimens were precharged for 3 h time with 1.2 mA/cm2 in two different aqueous media: 1 M H2SO4 added with 0.25 g/l As2O3 and 3.5% of NaCl solution. Hydraulic fracture tests were performed at different ramps of pressure: 7000, 220, 80, 60 and 30 MPa/h, respectively. Hydrogen damage was more marked when the acid aqueous medium (1 M H2SO4 + 0.25 g/l As2O3) was employed. In this case, a higher hydrogen concentration was introduced, leading to hydrogen decohesion micromechanisms (HEDE) near the notched region, especially when tests were performed at 60 MPa/h. Hydrogen embrittlement susceptibility is discussed in terms of the microstructural singularities and the operative fracture micromechanisms observed in each case.

Thermodynamic modeling and analysis of cascade hydrogen refuelling with three-stage pressure and temperature for heavy-duty fuel cell vehicles

Recently, the development of heavy-duty fuel cell vehicles (HDFCVs) has received intense attention. Unlike the refuelling protocol of SAE J2601 for light-duty fuel cell vehicles, the SAE J2601-2 for HDFCVs does not propose a specific filling strategy but only specifies the limits that need to be observed for safety. Refuelling data for HDFCVs at hydrogen refuelling station (HRS) shows that refuelling parameters are often set conservatively, resulting in long refuelling time. To shorten the refuelling time, energy consumption and power demand of the cooling system, we establish a detailed three-stage pressure filling model to study the effects of pressure ramp rate (PRR), initial pressure, number of onboard tanks and precooling temperature on the filling time. Then, a three-stage temperature precooling method is proposed simultaneously, whose cooling energy and power of the heat exchanger are compared with the single-stage temperature precooling method. Research shows that three-stage and two-stage pressure filling can reduce the average pressure difference between the station-side and the vehicle-side storage tanks, thereby reducing the Joule-Thomson heat generated by the reduction valve throttling and the heat exchanger energy consumption. Increasing the PRR and initial pressure can significantly and directly shorten the filling time. Increasing the number of onboard tanks and decreasing precooling temperature have little effect on the filling time but reduce the final hydrogen temperature in the onboard tank, which is beneficial to increase the PRR further to shorten the filling time. Within the ambient temperature range set in this article, compared with the single-stage temperature precooling method, the three-stage temperature precooling method can reduce the maximum peak cooling power by 16.69%–17.38% without increasing the total cooling energy of the heat exchanger and onboard tank's final hydrogen temperature, reducing equipment investment in cooling systems. This research is significant for optimizing HRS design and operation strategies.

The collision-induced absorption of H2 near 1.20 µm: Subatmospheric measurements and validation tests of calculations

The weak binary collision-induced absorption (CIA) of molecular hydrogen is measured at room temperature in the first overtone region near 1.20 µm. Binary absorption coefficients are derived by cavity ring down spectroscopy (CRDS) at 28 selected spectral points sampling the (2–0) band between 7974 and 8650 cm−1. While all previous studies used high density samples, the sensitivity of the CRDS method allowed deriving accurate CIA by using pressure ramps of pure H2 limited to a maximum pressure of 1 atm. After subtraction of the Rayleigh contribution, a purely quadratic pressure dependence is obtained for the absorption coefficient at each measurement point and the CIA binary coefficients are derived with a 1.5 % accuracy. The comparison to theoretical values widely used for astronomical applications shows deviations values between 5 and 25 %.

Integrating run-to-run control with feedback control for a spatial atomic layer etching reactor

Semiconductor manufacturing employs an intricate framework of processes that require accurate design specifications at the nanoscale level. Thermal atomic layer etching fulfills these stringent criteria in an exemplary manner by conducting top-down removal of transistor films to further downsize thicknesses and facilitate transistor densification on wafers. However, it has low productivity. Thus, a spatial sheet-to-sheet reactor is appropriate for achieving high throughput while maintaining substrate quality. In order to continuously regulate the process, a run-to-run (R2R) controller coupled with a continuous feedback proportional–integral (PI) controller is proposed to mitigate a kinetic shift disturbance and a continuous pressure ramp disturbance through a multivariate input correction procedure. A tuning methodology is employed to determine the optimal tuning parameters to enhance the performance of the R2R and PI controller response to their respective disturbances. Results indicate that the combined R2R and PI controller outperforms the sole R2R controller by minimizing the amount of input correction needed to minimize the etching per cycle offset from the setpoint.

The water vapor self-continuum absorption at 8.45 µm by optical feedback cavity ring down spectroscopy

The accurate knowledge of the water vapor absorption in the 10 µm atmospheric window is of strong importance because this spectral range coincides with the maximum black body emission of Earth. Presently, the water vapor self-continuum is measured at the 1185 cm−1 (8.45 µm) spectral point, located in the most transparent interval of the 10 µm window. Measurements are performed at four temperatures ranging from 296 to 308 K using a newly developed Optical Feedback Cavity Ring Down Spectrometer (OF-CRDS). Self-continuum cross-sections, CS, are derived from the pressure dependence of the absorption during pressure ramps of pure water vapor up to 18 mbar. From the quadratic pressure dependence observed for the absorption coefficient at each temperature, we derived the value of the cross-section (CS=0.996(12)×10−22cm2 molecule−1atm−1 at 296 K) and its temperature dependence. These results are discussed in relation with previous literature measurements available in the 10 µm window. Our cross-section is found about 20% smaller than the MT_CKD_4.1 value and the available experimental works seem to indicate that the MT_CKD_4.1 temperature dependence is overestimated.

Accurate absolute absorption cross-sections of the ozone Wulf bands at 1 µm range: measurements with high-resolution cw-CRDS laser techniques

Ozone plays a major role in atmospheric chemistry and radiative processes with an impact on climate and ecosystems being also considered as a possible biosignature species in exoplanetary observations. This makes important an extension of accurate laboratory data to various spectral ranges. The present work provides absolute absorption cross-sections of ozone accurate to about 3% in the near-IR range around 1 µm using for the first time a continuous-wave cavity-ring-down spectrometer (cw-CRDS) for recording the transitions above the first dissociation threshold of O3. This has permitted high-sensitivity and high-resolution measurements covering the region from 9745 to 10850 cm−1 corresponding to the transitions from the electronic ground state to spin-rovibronic levels of excited triplet electronic states 3A2 and 3B2 that form the Wulf band system. Two complementary methods based on the stationary recording with the quasi-continuous laser tuning and on the pressure ramp measurements at carefully chosen grids of wavenumbers were implemented and provided very well consistent results within 2% on average. The experimental integrated absorption intensity in the range under the study is evaluated as 1.393×10−20 (± 2%) cm/molecule. The comparison with the available published data of continuous recordings shows that our absorption cross-sections are much more accurate, particularly in the region with complex partly resolved spin-rovibronic spectral patterns. This region corresponds to a transparency near-IR window of the water vapor and is thus well suited for atmospheric applications. The theoretical modeling of the measured spectra using eight rovibronic bands is discussed. The experimental absorption cross-sections at the dense grid of wavenumbers are provided in the electronic supplementary files, which could be used as new reference data in the 9745 to 10850 cm−1 range.

Effects of filling strategies on hydrogen refueling performance

In order to ensure the safety of hydrogen refueling systems and fuel cell vehicles under various filling conditions, the filling parameters are usually set very conservatively, leading to waste energy consumption and investment. The lumped parameter hydrogen gas model and one-dimension tank wall model of the hydrogen filling process previously proposed by our team were extended and improved to the entire hydrogen refueling system by considering the Joule-Thomson effect, kinetic energy and using a more accurate model of the heat transfer coefficients between the inner tank wall and hydrogen gas and between the outer tank wall and ambient. Based on our validated model, the effects of constant and two-stage average pressure ramp rates (APRRs) and precooling/inlet temperatures on refueling performances were investigated, respectively. Compared with the optimal filling strategy of the reference paper, where a constant APRR is the best, our two-stage APRRs can further reduce the cooling power for various inlet temperatures without increasing the cooling energy. For example, maximum cooling power can be reduced by 23.8% at the inlet temperature of −20 °C. Compared with the previous research result obtained using a constant inlet temperature solved by the analytical solution, the two-stage inlet temperatures can further reduce the cooling power by 16.3% at an APRR of 0.428 MPa/s without increasing the cooling energy.

Sour-Rated 10,000-psi System High-Temperature Gas Development Wells: Sustaining the Malaysian National Gas Supply Through a Journey of Optimization in North Malay Basin

Summary High temperature (HT), high carbon dioxide (CO2) coupled with hydrogen sulfide (H2S) contents, and rapid pore pressure fracture gradient (PPFG) pressure ramp increase in gas development wells can lead to significant capital expenditures for operators. Such wells typically need high corrosion resistance alloy material with at least a 10,000-psi (10-ksi)-rated system to complete. The deep reservoirs of the North Malay Basin, offshore peninsular Malaysia, also fall into the described category. In this paper, we aim to share the optimization journey, applications, and learnings of the company’s HT sour-rated 10-ksi gas development wells through several phases, besides fulfilling the gas delivery need for the country. In addition, we identify engineering and operational optimizations to reduce the well’s time and cost while upholding the safety of the crew as a top priority. The sour-rated HT gas development campaign for the company began in the year 2017, followed by a second campaign in the year 2018. Our focus centers on the third campaign, which concluded in the year 2022. A total of four, three, and four wells were drilled and completed in the first, second, and third campaigns respectively. The company’s wells engineering team applied Lean methodologies that covered the entire Plan-Do-Check-Adjust cycle to achieve optimization. Using well data, learning from experiences, working together, maintaining consistency, and pursuing ongoing enhancements are the main factors that ensure positive optimization outcomes. Fit-for-purpose drilling and completions equipment design and application, rig offline capabilities planning, wellhead dummy hanger plug design for offline cementing, intervention-less production packer setting device, offline annulus nitrogen cushion fluids displacement, and other applications will be explained in the paper. In this paper, we describe the operational challenges faced and outline the applied optimizations that led to significant improvements in the well performance compared with targets and previous campaigns. The optimization efforts by the wells team extended from the engineering phase to the execution stage, including the use of in-house digital capabilities to monitor well performance, in alignment with industry practice. The recent campaign post-optimization concluded with no safety incidents, average per well more than 48 days ahead with 39% lower cost than previous campaigns, average of 5.6% overall well nonproductive time (NPT), and achieved first gas to meet the country’s power generation demand. Furthermore, the motivating optimization results also coupled with 25% more production results compared with the prognosed. The positive results of this optimization journey were significantly influenced by transparent, collaborative, and proactive communication across different departments.

Orthostatic Stress and Baroreflex Sensitivity: A Window into Autonomic Dysfunction in Lone Paroxysmal Atrial Fibrillation.

The abnormal neural control of atria has been considered one of the mechanisms of paroxysmal atrial fibrillation (PAF) pathogenesis. The baroreceptor reflex has an important role in cardiovascular regulation and may serve as an index of autonomic function. This study aimed to analyze the baroreceptor reflex's role in heart rate regulation during upright tilt (HUT) in patients with lone PAF. The study included 68 patients with lone PAF and 34 healthy individuals who underwent baroreflex assessment. Parameters such as baroreflex sensitivity (BRS), number of systolic blood pressure (BP) ramps, and the baroreflex effectiveness index (BEI) were evaluated. The study found that PAF patients had comparable resting BPs and heart rates (HRs) to healthy individuals. However, unlike healthy individuals, PAF patients showed a sustained increase in BP with an upright posture followed by the delayed activation of the baroreceptor function with a blunted HR response and lower BEI values. This indicates a pronounced baroreflex impairment in PAF patients, even at rest. Our data suggest that together with BRS, BEI could be used as a marker of autonomic dysfunction in PAF patients, making it important to further investigate its relationship with AF recurrence after ablation and its involvement in cardiovascular autonomic remodeling.

Simulations of the effect of smectite‐to‐illite transition in shales on permeability and overpressures using a stochastic approach, a Norwegian margin case study

AbstractThe smectite‐illite transition in shales due to subsidence, temperature changes and diagenesis influences many processes in a sedimentary basin that can contribute to overpressure build up like reducing the shale permeability. The smectite‐rich layers can form sealing barriers to fluid flows that will influence pore pressure prognosis for drilling campaigns, contribute to sealing caprocks for possible CO2 storage and to sealing of plugging and abandonment wells. In this work, we have included the diagenetic smectite‐illite transition into a three‐dimensional pressure simulation model to simulate its effect on pressure build‐up due to reduced shale permeabilities over geological time scale. We have also tested effect of thermal history and potassium concentration on the process of smectite‐illite transition and the associated smectite‐illite correction on permeability. A new smectite‐illite correction has been introduced, to mimic how shale permeability will vary dependent on the smectite‐illite transition. Stochastic Monte Carlo simulations have been carried out to test the sensitivity of the new correction parameters. Finally, a 3D Monte Carlo pore pressure simulation with 1000 drawings has been carried out on a case study covering Skarv Field, and Dønna Terrace offshore Mid‐Norway. The simulated mean overpressures are in range with observed overpressures from exploration wells in the area for the Cretaceous sandy Lysing Formation and for the two Cretaceous Intra Lange Formation sandstones. The simulated smectite content versus depth is in line with published XRD dataset from wells. The corresponding modelled present‐day permeabilities for the shales including the smectite‐illite transition are two magnitudes higher than measured permeabilities on small samples in the laboratory using transient decay method. The measured permeabilities are in the range of 2.66·10−18 to 3.94·10−22 m2 (2695 to 0.39 nD) for the North Sea database and represent the end members for shales‐permeabilities with the lowest values, since the small samples are selected with no or minor natural fractures. This work shows that by upscaling shale permeabilities from mm‐scale to km scale, natural fractures and sedimentary heterogeneities will increase the shale permeabilities with a factor of two and that by including permeability correction controlled by the smectite fraction, pressure ramp can be simulated due to diagenesis effect in shales.

How the cylinder initial conditions affect the HCNG refuelling process - A thermodynamic analysis to determine the most effective filling parameters

The hydrogen compressed natural gas (HCNG) blends play a key role in the European Hydrogen Roadmap targets achievement. The HCNG refuelling stations can be built up by upgrading the existing compressed natural gas stations. This work investigates the thermodynamic of HCNG refuelling processes to determine the impact on gas temperature due to the Joule-Thomson effect, heat transfer through the cylinder wall, the kinetic energy conversion in internal energy, and compression contribution during the fast fill-up. Specifically, the vehicle tank initial conditions and the refuelling parameters have been analysed, evaluating how they affect the final refuelling temperatures, filled mass, relative states of charge, and refuelling times. With an average pressure ramp rate of 0.18 MPa/s, at initial cylinder conditions of 10 °C and 9 MPa, the 0.065 m3 and 0.15 m3 tanks reach a SOC of 93.83% and 65.32% and final temperature of 82.5 °C and 44.5 °C, respectively.

Analisis Uji Permeabilitas Total Sumur Berdasarkan Well Completion Test Pada Sumur RL-25 Lapangan Panas Bumi Area CLX

Well completion test (Well Completion test) in general is a test to determine the characteristics and potential production wells as well as provide information about the truth of targeting achieved in drilling include permeable zone data. Activities include exploratory well completion test the depth, temperature and pressure measurement wells, water loss test (test of water lost), gross permeability test (total permeability test). From the analysis of pressure and temperature ramp then gained the feed zone wells MKU RL-25 1660-2000. Water loss test aims to determine the permeable area by injecting cold water into the well. Based on data from the test water loss KTE position is placed on the well depth of 2000 MKU to RL-25 with such tools will be submerged in the water column. Injectivity is a relationship between the flow rate of water injected into the well with the measured pressure in the permeable area. Injectivity (i) an average of 802.681 lpm/Ksc and specific capacity (Ks) averaging 5.029 lpm/meter for wells RL-25. The well RL-25 has a slope (m) of 12 Ksc with pressure at 1 hour (P1 hour) amounted to 45.55 Ksc and initial pressure (Pi) of 32 Ksc with the assumption that the viscosity (μ) of 2.13x10-4 Pa.s and transmissivity ( kh) of 1.753179 darcy meter with skin factor (s) of -0.176.Maka of the data injectivity test get 35 Kg/s that can be estimated at 126 tons/hour and by Spesific Steam Comsumsion to generate electric power of 1 MW at 8 ton/h/MW it can result amounted to 15.75 MW.

Experimental determination of Rayleigh scattering cross-sections at 408 nm

Cavity ring-down spectroscopy (CRDS) has been applied to retrieve accurate Rayleigh scattering cross-sections, {upsigma }_{mathrm{Rayl}.} for a set of atmospheric gases at ~ 408 nm. Step pressure changes and pressure ramps were used in three different but similar optical cavities to measure light extinction by N2, O2, Ar, CO, CO2, N2O, CH4 and synthetic air (SA). The experimentally determined {upsigma }_{mathrm{Rayl}.} were compared with {upsigma }_{mathrm{Rayl}.} values calculated for these atmospheric gases using knowledge of extrapolated literature values of the refractive index (n) and King correction factors measured in different spectral regions.The difference between measured and calculated {upsigma }_{mathrm{Rayl}.} using the most recently published dispersion relationship for N2O and CH4 is ~ 0.6%. This confirms the improved accuracy of the new dispersion relationship. The calculated and measured {upsigma }_{mathrm{Rayl}.} agreed on average within 0.6%, 2.4%, 1.2%, 2.2%, and 1.5% for the gases CO2, N2 O2, SA, and Ar at ~ 408 nm. However, for CO, the difference is 4.1%, i.e. more than twice the error. This implies that improved knowledge of the dispersion relationship for CO, and thus the refractive index and King correction factors, would be of value to calculate {upsigma }_{mathrm{Rayl}.} in the blue spectral region.

Spontaneous Cardiac Baroreflex Sensitivity in Young, Healthy Black and White Adults: Influence of Race and Sex

Background: Black (BL) individuals living in the United States are more likely to develop hypertension and cardiovascular disease compared to their White (WH) counterparts. However, studies investigating racial differences in blood pressure regulation and baroreflex sensitivity (BRS) are limited and have reported equivocal results. Furthermore, despite BL females also having a high prevalence of hypertension and cardiovascular disease, sex differences are often not considered. Additionally, baroreflex effectiveness index (BEI) is a newer measure used to estimate baroreflex function, yet studies have not examined the influence of sex or race on BEI. Therefore, the purpose of this project was to investigate the effects of both race and sex on cardiac BRS and BEI. We hypothesized that BL individuals would have lower cardiac BRS and BEI than WH individuals. Methods: We studied 88 young healthy adults, 28 BL males (21 ± 3 years; mean ± SD), 17 WH males (24 ± 4 years), 15 BL females (21 ± 3 years), and 28 WH females (23 ± 4 years). Heart rate (ECG) and beat-to-beat arterial blood pressure (finger photoplethysmography) were continuously recorded during a five-minute resting baseline. Cardiac BRS was measured using the Sequence Method, by identifying the gain of the relationship between systolic blood pressure and RRI from sequence(s) of three or more consecutive heartbeats in which systolic blood pressure and RRI change in the same direction. BEI was quantified by baroreflex-driven ramps relative to all systolic blood pressure ramps. Results: Cardiac BRS was significantly higher in BL individuals (31 ± 15 ms/mmHg) compared to WH individuals (25 ± 11 ms/mmHg; main effect of race, p = 0.02). Interestingly, post hoc comparisons revealed that this was only true within the males (p = 0.03), but not females (p = 0.63). However, there was no difference in cardiac BRS between males and females (main effect of sex, p = 0.35) and no interaction between sex and race (p = 0.27). There were also no effects of race (p = 0.65) or sex (p = 0.15) on BEI. Conclusion: These preliminary data suggest that, in contrast to our hypothesis, young BL individuals have higher cardiac BRS compared to WH individuals; an effect that is only present in males. In contrast, BEI was not influenced by race or sex. Collectively, our findings do not suggest that lower cardiac BRS plays a major role in the higher prevalence of cardiovascular disease in BL individuals. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Thermodynamic parametric analysis of refueling heavy-duty hydrogen fuel-cell electric vehicles

Reliable design and safe operation of heavy-duty hydrogen refueling stations are essential for the successful deployment of heavy-duty fuel cell electric vehicles (FCEVs). Fueling heavy-duty FCEVs is different from light-duty vehicles in terms of the dispensed hydrogen quantities and fueling rates, requiring tailored fueling station design for each vehicle class. In particular, the selection and design of the onboard hydrogen storage tank system and the fueling performance requirements influence the safe design of hydrogen fueling stations. A thermodynamic modeling and analysis are performed to evaluate the impact of various fueling parameters and boundary conditions on the fueling performance of heavy-duty FCEVs. We studied the effect of dispenser pressure ramp rate and precooling temperature, initial tank temperature and pressure, ambient temperature, and onboard storage design parameters, such as onboard storage pipe diameter and length, on the fueling rate and final vehicle state-of-charge, while observing prescribed tank pressure and temperature safety limits. An important finding was the sensitivity of the temporal fueling rate profile and the final tank state of charge to the design factors impacting pressure drop between the dispenser and vehicle tank, including onboard storage pipe diameter selection, and flow coefficients of nozzle, valves, and fittings. The fueling rate profile impacts the design and cost of the hydrogen precooling unit upstream of the dispenser.

Combined Mud-Cooling, MPD Techniques Enable HP/HT Drilling in Egypt

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 210252, “Drilling the Deepest HP/HT Onshore Exploration Well Using a Combination of Mud-Cooling and MPD Techniques: A Field Case Study From the Nile Delta of Egypt Targeting a Mesozoic Carbonate Platform,” by Mahmoud El-Husseiny, Egyptian Natural Gas Holding Company, and Taher Elfakharany, Al-Azhar University. The paper has not been peer reviewed. _ The complete paper reviews the successful application of a mud-cooling and managed-pressure-drilling (MPD) system in a high-pressure/high-temperature (HP/HT) well to explore the potential of the Mesozoic carbonate platform with a pressure ramp and narrow mud-weight window (NMWW) in the Nile Delta. The constant bottomhole pressure (CBHP) variation of MPD in combination with mud cooling was used to drill from the middle of the pressure ramp to the target depth, maintaining the mud-inlet temperature at approximately 50°C. Geological Targets and Geohazards The primary objective of Well T-1 is the edge of a Mesozoic carbonate platform. These carbonates are expected to be high-energy shallow marine deposits with fair reservoir properties (20–50% net-to-gross, 5–10% porosity). The secondary objectives are turbiditic sandstone channels of the Oligocene. These sandstones are expected to have 9–20% porosity and 50–300 md permeability. Potential Middle and Late Miocene geohazards include pressure rampup associated with losses, kicks, and borehole degradation, including tight holes, overpull, and caves; and reported sticking and hangup events. The HP domain begins below approximately 4000 m. Potential Oligocene to Paleocene geohazards include NMWWs associated with losses, kicks, and simultaneous gains and losses (ballooning); borehole degradation, including tight holes, overpull, and caves; and sticking and hangup events. The HP and HT domains begin below approximately 4500 m. Potential Mesozoic carbonate geohazards include possible losses of fractured and pressure-regressed carbonates. Mud-Cooling Technique Concept and Equipment The mud cooler consists of two circuits. In the first, hot mud is circulated through a dual mud cooler using a centrifugal pump. Because of heat exchange through the plate heat exchanger, the mud is cooled and transferred back into the active mud system. The discharge of cold mud takes place upstream of the point where the suction of hot mud occurs. In the second circuit, a fluid mixed with water and glycol is circulated between a dual air cooler and the dual mud cooler using a dedicated pump. When passing through the plate heat exchanger, this mixture of water and glycol is evacuated. When this mixture returns to the dual air cooler, it is cooled using high-performance ventilators. The mud-cooling system features 16 ventilators. The efficiency of the mud-cooling system is adjusted with a number of operated ventilators. The mud-cooling units used in this well consist of two dry air coolers and two sets of air fans (Fig. 1), with each set containing 24 fans. A mixture of 10% glycol and water was used as a cooling fluid.

Thermomechanical behaviour of well cement in different geological formations under the coupled effects of temperature and pressure

It is crucial to ensure that the cement sheaths remain intact in all types of deep well applications subject to high temperatures and high pressures underground. It should be noted, however, that the behaviour of annulus cement sheath is not self-controlled and is governed by the response of steel casing and the surrounding rock formation in such extreme underground conditions. In this study, we investigate the thermomechanical response of wellbore materials in a typical oil well consisting of steel casing, annulus cement sheaths and surrounding rock formations subjected to continuous steam injection. A section of an oil well was simulated by using the COMSOL Multiphysics, a finite element method, using Class G Portland cement as the annulus cement. In two formation scenarios, stiff (carbonate) and compliant (sandstone), temperature and pressure were coupled to evaluate wellbore material behaviour. It was found that wellbore materials in carbonate were more susceptible to stress than those in sandstone. Despite the fact that all materials reached their highest temperatures in both formations, the retention time of the maximum temperature in the cement sheath in sandstone was shorter than in carbonate. Regardless of the thickness of the cement sheath, the highest strains were located at the casing-cement interface in carbonates. As a result of the temperature and pressure ramp, the cement sheath in sandstone failed by generating tensile radial cracks along the lowest layer thickness of the cement sheath. In compliant formations such as sandstone, the cement sheath would likely fail due to tensile cracking along its lowest thickness.