Factors Affecting Well Productivity - II. Drilling Fluid Particle Invasion into Porous Media

Dispersion characteristics are important factors affecting groundwater solute transport in porous media. In marine environments, solute dispersion leads to the formation of freshwater aquifers under islands. In this study, a series of model tests were designed to explore the relationship between the dispersion characteristics of solute in calcareous sands and the particle size, degree of compactness, and gradation of porous media, with a discussion of the types of dispersion mechanisms in coral sands. It was found that the particle size of coral sands was an important parameter affecting the dispersion coefficient, with the dispersion coefficient increasing with particle size. Gradation was also an important factor affecting the dispersion coefficient of coral sands, with the dispersion coefficient increasing with increasing d10. The dispersion coefficient of coral sands decreased approximately linearly with increasing compactness. The rate of decrease was −0.7244 for single-grained coral sands of particle size 0.25–0.5 mm. When the solute concentrations and particle sizes increased, the limiting concentration gradients at equilibrium decreased. In this study, based on the relative weights of molecular diffusion versus mechanical dispersion under different flow velocity conditions, the dispersion mechanisms were classified into five types, and for each type, a corresponding flow velocity limit was derived.

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Liquid–liquid gravity displacement in a vertical fracture during drilling: Experimental study and mathematical model

Energy Exploration & Exploitation ◽

10.1177/0144598719874467 ◽

2019 ◽

Vol 38 (2) ◽

pp. 533-554

Author(s):

Dong Xiao ◽

Yingfeng Meng ◽

Xiangyang Zhao ◽

Gao Li ◽

Jiaxin Xu

Keyword(s):

Mathematical Model ◽

Drilling Fluid ◽

Effective Means ◽

Fluid Density ◽

Shape Factors ◽

Fracture Width ◽

Factors Affecting ◽

Double Substrate ◽

Fracture Height ◽

Liquid Displacement

Gravity displacement often occurs when drilling a vertical fractured formation, causing a downhole complexity with risk of blowout and reservoir damage, well control difficulty, drilling cycle prolongation, and increased costs. Based on an experimental device created for simulating the gravity displacement, various factors affecting the displacement quantity were quantitatively evaluated by simulating the fracture width, asphalt viscosity, drilling fluid density, and viscosity under different working conditions, and a liquid–liquid displacement law was obtained. Using the theories of rock mechanics, fluid mechanics, and seepage mechanics, based on conformal mapping, as well as a fracture-pore double substrate fluid flow model, we established a steady-state mathematical model of fractured formation liquid–liquid gravity displacement by optimizing the shape factors and using a combination of gravity displacement experiments to verify the feasibility of the mathematical model. We analyzed the influence of drilling fluid density, fracture height and length, and asphalt viscosity on displacement rate, and obtained the corresponding laws. The results show that when the oil–fluid interface is stable, the fracture width is the most important factor affecting the gravity displacement, and plugging is the most effective means of managing gravity displacement.

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Application of Implicit Pressure-Explicit Saturation Method to Predict Filtrated Mud Saturation Impact on the Hydrocarbon Reservoirs Formation Damage

Mathematics ◽

10.3390/math8071057 ◽

2020 ◽

Vol 8 (7) ◽

pp. 1057 ◽

Cited By ~ 4

Author(s):

Mingxuan Zhu ◽

Li Yu ◽

Xiong Zhang ◽

Afshin Davarpanah

Keyword(s):

Porous Media ◽

Water Saturation ◽

Drilling Fluid ◽

Formation Damage ◽

Drilling Mud ◽

Oil Viscosity ◽

The Core ◽

Oil Flow ◽

Lower Porosity ◽

Saturation Method

Hydrocarbon reservoirs’ formation damage is one of the essential issues in petroleum industries that is caused by drilling and production operations and completion procedures. Ineffective implementation of drilling fluid during the drilling operations led to large volumes of filtrated mud penetrating into the reservoir formation. Therefore, pore throats and spaces would be filled, and hydrocarbon mobilization reduced due to the porosity and permeability reduction. In this paper, a developed model was proposed to predict the filtrated mud saturation impact on the formation damage. First, the physics of the fluids were examined, and the governing equations were defined by the combination of general mass transfer equations. The drilling mud penetration in the core on the one direction and the removal of oil from the core, in the other direction, requires the simultaneous dissolution of water and oil flow. As both fluids enter and exit from the same core, it is necessary to derive the equations of drilling mud and oil flow in a one-dimensional process. Finally, due to the complexity of mass balance and fluid flow equations in porous media, the implicit pressure-explicit saturation method was used to solve the equations simultaneously. Four crucial parameters of oil viscosity, water saturation, permeability, and porosity were sensitivity-analyzed in this model to predict the filtrated mud saturation. According to the results of the sensitivity analysis for the crucial parameters, at a lower porosity (porosity = 0.2), permeability (permeability = 2 mD), and water saturation (saturation = 0.1), the filtrated mud saturation had decreased. This resulted in the lower capillary forces, which were induced to penetrate the drilling fluid to the formation. Therefore, formation damage reduced at lower porosity, permeability and water saturation. Furthermore, at higher oil viscosities, due to the increased mobilization of oil through the porous media, filtrated mud saturation penetration through the core length would be increased slightly. Consequently, at the oil viscosity of 3 cP, the decrease rate of filtrated mud saturation is slower than other oil viscosities which indicated increased invasion of filtrated mud into the formation.

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An investigation of hydromechanical effect on well productivity in fractured porous media using full factorial experimental design

Journal of Petroleum Science and Engineering ◽

10.1016/j.petrol.2019.106233 ◽

2019 ◽

Vol 181 ◽

pp. 106233 ◽

Cited By ~ 6

Author(s):

T. Kadeethum ◽

S. Salimzadeh ◽

H.M. Nick

Keyword(s):

Porous Media ◽

Experimental Design ◽

Fractured Porous Media ◽

Factorial Experimental Design ◽

Well Productivity ◽

Full Factorial Experimental Design ◽

Full Factorial

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Evaluation of Constitutive Equation for Stress in Solids in Porous Media Composed of Bridging Agents Used in Drilling Fluids

Materials Science Forum ◽

10.4028/www.scientific.net/msf.727-728.1878 ◽

2012 ◽

Vol 727-728 ◽

pp. 1878-1883 ◽

Cited By ~ 2

Author(s):

Bruno Arantes Moreira ◽

Flávia Cristina Assis Silva ◽

Larissa dos Santos Sousa ◽

Fábio de Oliveira Arouca ◽

João Jorge Ribeiro Damasceno

Keyword(s):

Porous Media ◽

Constitutive Equation ◽

Filter Cake ◽

Drilling Fluid ◽

Fluid Loss ◽

Drilling Fluids ◽

Oil Well ◽

Well Drilling ◽

Drilling Operations ◽

The Stability

During oil well drilling processes in reservoir-rocks, the drilling fluid invades the formation, forming a layer of particles called filter cake. The formation of a thin filter cake and low permeability helps to control the drilling operation, ensuring the stability of the well and reducing the fluid loss of the liquid phase in the interior of the rocks. The empirical determination of the constitutive equation for the stress in solids is essential to evaluate the filtration and filter cake formation in drilling operations, enabling the operation simulation. In this context, this study aims to evaluate the relationship between the porosity and stress in solids of porous media composed of bridging agents used in drilling fluids. The concentration distribution in sediments was determined using a non-destructive technique based on the measure of attenuated gamma rays. The procedure employed in this study avoids the use of compression-permeability cell for the sediment characterization.

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AN EXPERIMENTAL INVESTIGATION OF FACTORS AFFECTING ELASTIC WAVE VELOCITIES IN POROUS MEDIA

Geophysics ◽

10.1190/1.1438493 ◽

1958 ◽

Vol 23 (3) ◽

pp. 459-493 ◽

Cited By ~ 443

Author(s):

M. R. J. Wyllie ◽

A. R. Gregory ◽

G. H. F. Gardner

Keyword(s):

Experimental Investigation ◽

Porous Media ◽

Oil And Gas ◽

Velocity Data ◽

Velocity Measurements ◽

Factors Affecting ◽

Gas Saturation ◽

Wave Velocities ◽

Time Average ◽

Made In

An experimental investigation has been made of the factors which affect the velocity of vibratory signals in porous media. It is shown from the results of experiments carried out on appropriate natural and synthetic porous systems that the time‐average formula previously suggested by Wyllie, Gregory, and L. W. Gardner is of considerable utility. This formula states that [Formula: see text] where [Formula: see text] measured, [Formula: see text] in saturating liquid, [Formula: see text] in rock solid, and ϕ=volumetric porosity fraction. The effects are examined of differential compacting pressures on the applicability of this formula to consolidated and unconsolidated rocks. It is shown that the time‐average relationship cannot be applied to determine the total volumetric porosity of carbonate rocks which are vugular and fractured. In such rocks, paradoxically, this circumstance may be advantageous because of the lithological information that may be obtained from an appropriate combination of velocity and nuclear log data. The effects of oil and gas saturation on velocity have been examined experimentally and are found to be comparatively minor. The combination of velocity data with information from electric logs in order to locate zones of oil and gas saturation is shown to be generally valuable; this is particularly so when holes are drilled with oil‐base mud. Some discussion is given of the possible effects on velocity measurements of the relative wettability of rock surfaces by various liquids. Owing to instrumental limitations, it cannot necessarily be assumed that measurements made in the laboratory are directly applicable to the interpretation of velocity data obtained under field conditions.

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