Top PDF Pressure and pressure derivative interpretation for vertical wells in naturally fractured and compressible formations

Pressure and pressure derivative 
		interpretation for vertical wells in naturally fractured and 
		compressible formations

Pressure and pressure derivative interpretation for vertical wells in naturally fractured and compressible formations

From the well testing point of view a homogeneous variation of the permeability is accounted by the permeability modulus which was introduced by Pedrosa (1986) and defined by Equation (10). Since then, several researchers have been presented. Escobar, Urazan and Trujillo (2018) recent presented a methodology for well test pressure interpretation in stress sensitive formations drained by horizontal wells. They did a good review of existing literature. Escobar et al (1996) studied the effect of the poisson ratio and the young modulus on well pressure behavior. Duan et al (1998) performed a sensitive analysis by numerical simulation and lab tests to study the influence of stress on naturally fractured parameters. They concluded that the sensitivities are generated mainly by the network of fractures.
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PRESSURE TRANSIENT BEHAVIOUR OF A HORIZONTAL STEAM INJECTION WELL IN A NATURALLY FRACTURED RESERVOIR

PRESSURE TRANSIENT BEHAVIOUR OF A HORIZONTAL STEAM INJECTION WELL IN A NATURALLY FRACTURED RESERVOIR

Most of the reservoirs on Earth are most likely to contain natural fractures and they are complex systems to characterize to engineers [1]. This makes it imperative to be able to characterize and understand the complex and irregular systems of a naturally fractured reservoir. The numerical and mathematical calculations depicting a naturally fractured reservoir are a challenge as its characterization is complex. The fractures and matrix of a naturally fractured reservoir have intrinsic properties compared to a single continuum reservoir. The matrix to fracture interactions also must be considered and characterize to properly model and evaluate naturally fractured reservoirs [2]. The application of pressure transient testing allows the reservoir to be described and the productivity evaluated. The pressure transient behaviour of steam injection wells in horizontal and vertical wells in a homogeneous reservoir has been well researched in literature. However, the pressure transient behaviour of a steam injection well in naturally fractured reservoirs has not been fully studied. This leaves a gap in understanding and fully characterizing reservoirs with natural fractures and a single horizontal steam injection well. Successful characterization of naturally fractured reservoirs penetrated by the steam injection well through pressure and pressure-derivative data will lead to the accurate identification of its performance with steam injection. The successful characterization of naturally fractured reservoirs with steam injection would be monumental as the majority of the reservoirs on Earth have fracture networks, with also steam injection
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Characterization of the naturally fractured reservoir parameters in 
		infinite conductivity hydraulically  fractured vertical wells by 
		transient pressure analysis

Characterization of the naturally fractured reservoir parameters in infinite conductivity hydraulically fractured vertical wells by transient pressure analysis

Tiab and Bettam (2007) presented a practical interpretation of the pressure behavior of a finite- conductivity hydraulically fractured vertical well located in a naturally fractured reservoir. The interpretation is based on analytical equations derived to determine permeability, fracture storage capacity ratio, interporosity flow coefficient, skin and wellbore storage from the pressure derivative plot without using type-curve matching technique. In other words, they implemented the TDS technique, Tiab (1993), for such systems. Part of the work presented by Escobar, Martinez and Montealegre (2009) was focused on the implementation of conventional analysis for the work presented by Tiab and Bettam (2007).
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Pressure derivative analysis for horizontal wells in shale reservoirs 
		under trilinear flow conditions

Pressure derivative analysis for horizontal wells in shale reservoirs under trilinear flow conditions

The behavior of fluids within a reservoir composed of very tight matrix, hydraulic fractures and natural fractures (usually induced at the time of hydraulic fracturing), in a horizontal well, can be interpreted using an analytical model known as trilinear flow model, formulated and verified by Brown (2009) and Brown et al. (2009). As implied by its name, the trilinear flow model assumes three linear flows during the productive life of the well and its interpretation was based on a series of previous work on the behavior of fluids in porous media, as well as in vertical and horizontal wells in naturally and/or hydraulically fractured reservoirs.
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Interpretation of pressure tests in uniform flux 
		fractured vertical wells with threshold pressure gradient in low 
		permeability reservoirs

Interpretation of pressure tests in uniform flux fractured vertical wells with threshold pressure gradient in low permeability reservoirs

unaltered, as flow is dominated by fracture flow and there is no impact of TPG on flow in high permeability fracture However, pressure derivative during pseudorradial flow regime deviates upwards from the horizontal line (with TPG = 0) making it difficult to obtain permeability due to TPG masking the pseudorradial flow regime. As dimensionless pressure gradient increases from 0 to 0.1, there is greater deviation and masking of pseudorradial flow regime with more inclined line from horizontal. It is interesting to notice that at late pseudorradial flow regime time, both pressure and pressure derivative are present and half-slope line behavior similar to the linear flow regime is observed.
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Numerical Modelling of Concrete Pressure on Vertical Formworks

Numerical Modelling of Concrete Pressure on Vertical Formworks

concrete has been cast in 15 blocks and it is possible to assign a different material property to each block. To simulate the casting process, the bottommost block has the material properties corresponding to time at the end of casting, while the top block has the material properties corresponding to time zero. Thus the resulting pressure distribution obtained corresponds to the time at which the wall has just been completely cast. It is relevant to investigate the pressures at the end of casting, as prior to that the concrete hasn’t reached its full height so the pressures will be less. Investigating pressures anytime
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Development and Evaluation of an Apparatus to Simulate and Measure the Lateral Pressure and Pore Pressure of a Sample of Fresh Concrete.

Development and Evaluation of an Apparatus to Simulate and Measure the Lateral Pressure and Pore Pressure of a Sample of Fresh Concrete.

using fundamental properties. In addition, he conducted a statistical analysis of existing data from other researchers. Yu proposed two mathematical models to predict the maximum pressure exerted by fresh concrete. One, the physical model, was derived theoretically from stress-strain relationships, pore pressure, consolidation, and hydration processes. In relating the pore pressure and hydration, Yu estimated the consumption of water in an element of fresh concrete. To solve the differential equation, Yu assumed values for several physical properties and used a graphical solution. The other equation, [2.11], was based on a multiple linear regression of data collected over a forty year period. Determination of the C c factor and C f factor is summarized in Table 2.3 and Table 2.4. Yu placed the restriction that the estimated pressure was not to exceed the unit weight of concrete times the height of placement.
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The pressure of concrete on vertical formwork in wide sections.

The pressure of concrete on vertical formwork in wide sections.

pressure. In normal formwork, the pore water pressure provides the major contribution to the maximum horizontal pressure and therefore.. any factor which increases t[r]

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Detection of Abnormal Formation Pressures using Drilling Parameters

Detection of Abnormal Formation Pressures using Drilling Parameters

It is existed about 70 km Northwest of Basra city in southern Iraq. West Qurna is one of the biggest oil fields in Iraq. This deep well was the fifteenth wells drilled by the Iraqi National Oil Company in West Qurna field of Southern Iraq. West Qurna 15 was the first well that has been drilled near the crest of West Qurna structure. It is extend from Upper Fars formation at surface to final depth at Najmah formation at 4400 m. This field contains a certain reserves predestined at 18 billion barrels and reserves potential is estimated at 40 billion barrels. Now, the production of the field is about 120,000 bbl/day, but it can reach to 1 million bbl /day. It is one of the oils light desired globally, the bottom hole pressure is around 7200 psi and the number of oil wells is 247 wells, while the number of water injection wells is 64 wells [3] .
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STUDIES ON THE FIRST DERIVATIVE OF THE VENTRICULAR PRESSURE PULSE IN MAN

STUDIES ON THE FIRST DERIVATIVE OF THE VENTRICULAR PRESSURE PULSE IN MAN

Valutes for PDRv The peak values for the first derivative of the ascending limb of the right ventricular pressure pulse recorded during the control period in patients without an abnormal[r]

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Experimental study on critical closing pressure of mudstone fractured reservoirs

Experimental study on critical closing pressure of mudstone fractured reservoirs

(2) The external pressure-permeability variation trend is roughly an exponential relationship, the external pressure-permeability which measured by high pressure permeability experiment not only includes the value when the stress loading but also contains the value when unloading stress, if we put two groups of experiment data to scattered chart, we could notice the permeability of the unloading process is lower than that in the loading process, the reason to this is in the process of loading stress, mudstone fracture occurred plastic deformation, when the stress unloading it cannot restore the original shape, leading to the decrease of permeability.
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Determination of Pressure Losses in Hydraulic Pipeline Systems by Considering Temperature and Pressure

Determination of Pressure Losses in Hydraulic Pipeline Systems by Considering Temperature and Pressure

The numerical model, which takes into account the actual changes of density and viscosity at the current oil pressure and temperature in order to overcome the above weakness, is suggested in this paper. Such an approach is novel and provides a new capacity for an accurate pressure drop analysis of advanced hydraulic systems.

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Pressure evaluation during dam break using weakly compressible SPH

Pressure evaluation during dam break using weakly compressible SPH

In this work, a dam break problem was solved using a weakly compressible SPH method. The obtained results were compared with experimental data from the literature. The kinematics of the flow is in relatively good agreement with available experimental data, especially at the begin- ning of the problem solution. Later, an absence of vis- cosity and turbulence modelling becomes evident, partic- ularly during the formation of the rolling wave and dur- ing its impact. After the rolling wave impact, a neglection of the gaseous phase is not appropriate, as well as two- dimensional simplification because air remains trapped under the rolling wave in experiments, and it escapes in the form of bubbles.
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The Study Of Pressure Derivative Of Bulk Modulus At Extreme Compression

The Study Of Pressure Derivative Of Bulk Modulus At Extreme Compression

Abstract: The present study reveals that the generalized Rydberg equation of state (EOS) with 𝑲 = 𝟓/𝟑, (i.e. the Holzapfel HO2-EOS) here 𝑲 be the infinite pressure value of first pressure derivative of bulk modulus, yields a remarkably good agreement with the Stacey reci procal 𝑲 -EOS of the lower mantle and the outer core of the earth upto a pressure of nearly 330 GPa. Values of 𝑲 and 𝑲 , the bulk modulus and its first order pressure derivative both at zero pressure, for the generalized Rydberg EOS with a fixed value of 𝑲 = 𝟓/𝟑 are found to be very close to the corresponding values for the Stacey EOS with 𝑲 = 2.4 and 3.0 respectively in case of the lower mantle and the outer core. The seismological data on P-K-ρ and K' are reproduced almost identically with the help of both the equation of state. It is emphasized that 𝑲 = 𝟓/𝟑 is not only a valid theoretical result obtained from the Thomas-Fermi model but also a thermodynamic requirement as found by Shanker et al. [Physics B (2006)]. We have also presented a comp arison of the results for iron at 300K, and found that the HO2 EOS is compatible with the Stacey reciprocal 𝑲 -EOS.
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Theoretical and experimental investigation of membrane distillation

Theoretical and experimental investigation of membrane distillation

different velocities and temperatures on the global mass transfer coefficient and flux were studied. The membrane showed high flux (18 Lm -2 h -1 , hot inlet temperature 80°C, cold inlet temperature 20°C) and good salt rejection (>99%) under tested conditions. The asymmetric structure caused a large flux difference as the hot feed passing through the lumen compared to the shell side. This phenomenon was analysed by considering the heat and mass balance across each layer, from which it was found that the skin layer combining with the exponential relation between the interface temperature and vapour pressure lead to the difference. VEDCMD was also tested with this module. In the experiments, the cold stream was drawn through the module on the shell side, and the degree of vacuum was increased by increasing the stream velocity. It was found that the global mass transfer coefficient increased as negative pressure was applied on the cold side under the same hydrodynamic and thermal conditions. For a comparison test with positive pressure for the cold flow, a maximum global mass transfer coefficient was also found when only the cold stream velocity increased, due to the skin layer effect. In this case, the flux was reduced dramatically by swapping the feed stream from inside the fibre to outside the fibre, due to the change of heat conduction and mass transfer sequence. Therefore, based on this study, it is important to consider both the heat and mass transfers in fabrication of MD membranes.
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The Initial Tangent of the Femoral Arterial Pressure Increase Is an Estimate of Left Ventricular Contractility in Patients Undergoing Cardiacsurgery

The Initial Tangent of the Femoral Arterial Pressure Increase Is an Estimate of Left Ventricular Contractility in Patients Undergoing Cardiacsurgery

pendent. Arterial pressure increase does most likely not only reflect left ventricular contractility, but is probably also affected by various variables which influence arterial compliance and pulse wave reflection, such as vascu- lar filling conditions, vasoactive drugs, and aortic impedance (Zc). Aging and numerous cardiovascular diseases common in cardiac surgery, e.g. arterial hypertension, lead to aortic stiffening responsible for an increased aortic impedance. Various methods to measure and estimate the individual Zc have been described [8] [16], however, due to the retrospective character of the study, Zc could not be assessed and included into the calculation of tan in .
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The Neurogenic Vasoconstrictor Effect of Digitalis on Coronary Vascular Resistance

The Neurogenic Vasoconstrictor Effect of Digitalis on Coronary Vascular Resistance

The coronary vasoconstrictor properties of digitals were evaluated in 61 anesthetized, openchest dogs after coronary sinus cannulation and under conditions of a constant heart rate (atrioventricular pacing) and near-constant blood pressure. The contribution of alpha adrenergic receptor stimulation to the digitalis-induced increase in coronary vascular resistance (CVR) was examined. With Na pentobarbital anesthesia (16 dogs), intravenous acetylstrophanthidin (0.5 mg) caused a significant (P<0.05) rise in CVR from 1 through 9 min after injection. The peak increase was +11±2% SE of the control of 1.8±0.2 mm Hg/cm 3 /min. The mean time to peak effect was 3 min, and to recovery was 21 min. Prior alpha adrenergic receptor blockade with phenoxybenzamine in 11 animals reduced (P<0.05) the acetylstrophanthidin-induced peak of CVR and substantially decreased (P<0.05) the time to recovery (5 min). Intravenous digoxin (1.0 mg) with Na pentobarbital anesthesia (five dogs) had no significant effect on CVR. However, with chloralose and urethane anesthesia (nine dogs) the same dose of digoxin produced a significant rise in CVR from 3 through 30 min. The peak increase was +20±3% of control (1.4±0.1 mm Hg/cm 3 /min). One-third the dose of intravenous digoxin (0.35 mg) produced a 9.5±1.0% increase in CVR (five additional dogs). Myocardial oxygen consumption did not change significantly in nine dogs after intravenous digoxin. In 10 additional dogs pretreated with phenoxy-benzamine and in 7 dogs pretreated […]
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A Reinterpretation of Historic Aquifer Tests of Two Hydraulically Fractured Wells by Application of Inverse Analysis, Derivative Analysis, and Diagnostic Plots

A Reinterpretation of Historic Aquifer Tests of Two Hydraulically Fractured Wells by Application of Inverse Analysis, Derivative Analysis, and Diagnostic Plots

The most useful tool for determining aquifer properties and estimating reliable yields of wells is the aquifer pumping test. The common graphical method of fitting type curves to data on a log-log plot to derive aquifer constants provides simple solutions to inverse problems, but can be subjective in nature and is prone to errors in individual judgment. The primary reason for these errors is that type curves representing different flow mechan- isms often have such similar shapes that each can provide relatively good visual fits to the same set of data. Computer assisted inverse analysis techniques, the process by which a theoretical curve is numerically fitted to a data set is generally regarded as less subject to individual bias. However, choice of incorrect models, for exam- ple, may still result in acceptable model fits to a data set even though the results are incorrect [32]. The possibil- ity of choosing an incorrect model based on an inadequate knowledge of site hydrogeology led Johns et al. [33] to state that the graphical method for aquifer test analysis represents a compliment to inverse analysis of aquifer tests.
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Nonlinear consolidation of vertical drains with coupled radial vertical flow considering time and depth dependent vacuum pressure

Nonlinear consolidation of vertical drains with coupled radial vertical flow considering time and depth dependent vacuum pressure

Further studies about consolidation improved by vacuum pressure showed that the vacuum pressure varied during the consolidation process. Laboratory tests indicated a linear decrease of negative pressure along the drainage path [17]. Some tests found that the decrease happened not only along the vertical direction but also the radial direction [18]. The analytical solutions for consolidation considering the loss of vacuum pressure were proposed. Geng et al. [8] presented a solution including the time-dependent surcharge loading, smear effect and well resistance. Wu et al. [19] solved the radial consolidation problem considering the decrease of vacuum pressure both in the radial and vertical direction. Perera et al. [20] considered the consolidation under vacuum pressure incorporating soil disturbance.
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Pressure and pressure derivative analysis for fractal 
		homogeneous reservoirs with power law fluids

Pressure and pressure derivative analysis for fractal homogeneous reservoirs with power law fluids

when injecting foam is given by Escobar, Martinez and Montealegre (2010) for composite systems where the injected foam or EOR fluid in injected in an oil Newtonian bearing formation. If the injected fluid behaves as dilatant, the Martinez, Escobar and Cantillo (2011b) provide a practical interpretation methodology. If the power-law flows through a double-porosity medium, then Escobar, Zambrano and Giraldo introduced an interpretation methodology using unique features found on the pressure and pressure derivative plot. If the well is partially completed and spherical flow takes place, this special situation was handled from the interpretation point of view by Escobar, Martinez and Bonilla (2012).
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