Comparisons of Uncoupled and Various Coupling Techniques for Practical Field Examples

SPE Journal ◽  
2006 ◽  
Vol 11 (01) ◽  
pp. 89-102 ◽  
Author(s):  
P. Samier ◽  
A. Onaisi ◽  
G. Fontaine
Keyword(s):  
Cold Water ◽  
Water Injection ◽  
Reservoir Properties ◽  
Simplified Approach ◽  
High Pressure High Temperature ◽  
Coupling Techniques ◽  
Rock Compressibility ◽  
Reservoir Simulator ◽  
Practical Field

Summary Generally, in classical reservoir studies, the geomechanical behavior of the porous medium is taken into account by the rock compressibility. Inside the reservoir simulator, the rock compressibility is assumed to be constant or to vary with the pressure of the oil phase. It induces some changes in the porosity field. During the depletion phase or the cold-water injection of high-pressure/high-temperature (HP/HT) reservoirs, the stress state in and around a reservoir can change dramatically. This process might result in rock movements such as compaction, induced fracturing, and enhancement of natural fractures and/or fault activation, which continuously modify the reservoir properties such as the permeabilities and the fault transmissibilities. Modifications of such parameters strongly affect the flow pattern in the reservoir and ultimately the recovery factor. To capture the link between flow and in-situ stresses, it becomes essential to conduct coupled reservoir-geomechanical simulations. This paper compares the use of five types of approach for the reservoir simulations:A classical approach with rock compressibility using only a reservoir simulator.A loose coupled approach between a reservoir simulator (finite volumes) and a geomechanical simulator (finite elements). At given user-defined steps, the hydrocarbon pressures calculated by the reservoir simulator are transmitted to the geomechanical tool, which computes the actual stresses and feeds back iteratively the modifications of the petrophysical properties (porosities and permeabilities) to the reservoir simulator.A one-way coupling: this approach is a simplification of the loose coupled approach in that the modifications are not fed back to the reservoir simulator.A simplified approach using permeability and porosity multipliers inside a reservoir simulator. These multipliers are user-defined curves and vary with the pressure of the oil phase. This approach uses only a reservoir simulator.A coupled approach in which the structural and the flow unknowns (displacement, pressure, and saturations) are solved simultaneously. These approaches are compared for two validation cases and two field cases described in the following.

scholarly journals Cyclic Subcritical Water Injection into Bazhenov Oil Shale: Geochemical and Petrophysical Properties Evolution Due to Hydrothermal Exposure

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4570
Author(s):  
Aman Turakhanov ◽  
Albina Tsyshkova ◽  
Elena Mukhina ◽  
Evgeny Popov ◽  
Darya Kalacheva ◽  
...  
Keyword(s):  
Energy Demand ◽  
Oil Shale ◽  
Oil And Gas ◽  
Subcritical Water ◽  
Pore Space ◽  
Water Injection ◽  
Microstructural Properties ◽  
Gas Generation ◽  
Geochemical Parameters

In situ shale or kerogen oil production is a promising approach to developing vast oil shale resources and increasing world energy demand. In this study, cyclic subcritical water injection in oil shale was investigated in laboratory conditions as a method for in situ oil shale retorting. Fifteen non-extracted oil shale samples from Bazhenov Formation in Russia (98 °C and 23.5 MPa reservoir conditions) were hydrothermally treated at 350 °C and in a 25 MPa semi-open system during 50 h in the cyclic regime. The influence of the artificial maturation on geochemical parameters, elastic and microstructural properties was studied. Rock-Eval pyrolysis of non-extracted and extracted oil shale samples before and after hydrothermal exposure and SARA analysis were employed to analyze bitumen and kerogen transformation to mobile hydrocarbons and immobile char. X-ray computed microtomography (XMT) was performed to characterize the microstructural properties of pore space. The results demonstrated significant porosity, specific pore surface area increase, and the appearance of microfractures in organic-rich layers. Acoustic measurements were carried out to estimate the alteration of elastic properties due to hydrothermal treatment. Both Young’s modulus and Poisson’s ratio decreased due to kerogen transformation to heavy oil and bitumen, which remain trapped before further oil and gas generation, and expulsion occurs. Ultimately, a developed kinetic model was applied to match kerogen and bitumen transformation with liquid and gas hydrocarbons production. The nonlinear least-squares optimization problem was solved during the integration of the system of differential equations to match produced hydrocarbons with pyrolysis derived kerogen and bitumen decomposition.

The Effect of Water Injection on Sustained Combustion in a Porous Medium

1970 ◽  
Vol 10 (02) ◽  
pp. 145-163 ◽  
Author(s):  
H.L. Beckers ◽  
G.J. Harmsen
Keyword(s):  
Cross Section ◽  
Combustion Zone ◽  
Water Injection ◽  
Combustion Process ◽  
Physical Reality ◽  
Porous Matrix ◽  
Theoretical Description ◽  
Air Injection ◽  
Injection Ratio

Abstract This paper gives a theoretical description of the various semisteady states that may develop if in an in-situ combustion process water is injected together with the air. The investigation bas been restricted to cases of one-dimensional flow without heat losses, such as would occur in a narrow, perfectly insulated tube. perfectly insulated tube. Different types of behavior can be distinguished for specific ranges of the water/air injection ratio. At low values of this ratio the injected water evaporates before it reaches the combustion zone, while at high values it passes through the combustion zone without being completely evaporated, but without extinguishing combustion. At intermediate values and at sufficiently high fuel in which all water entering the combustion zone evaporates before leaving it. Formulas are presented that give the combustion zone velocity as a function of water/air injection ratio for each of the possible situations. Introduction In-situ combustion of part of the oil in an oil-bearing formation has become an established thermal-recovery technique, even though its economic prospects are limited by inherent technical drawbacks. The process has been extensively investigated both in the laboratory and in the field, while theoretical studies have also been made. The latter studies showed how performance was affected by various physical and chemical phenomena, such as conduction and convection of phenomena, such as conduction and convection of heat, reaction rate and phase changes. The degree of simplification determined whether these studies were of an analytical or a numerical nature. Recently an improvement of the process has been proposed. This modification involves the proposed. This modification involves the injection of water together with the air. The water serves to recuperate the heat stored in the burned-out sand, which would otherwise be wasted. This heat is now used to evaporate water. The steam thus formed condenses downstream of the combustion zone, where it displaces oil. At sufficiently high water-injection rates unevaporated water is bound to enter the combustion zone because more heat is required for complete evaporation than is available in the hot sand. Experiments showed that even under these conditions combustion is maintained. The improvement consists in a lower oxygen consumption per barrel of oil displaced and lower combustion-zone temperatures. This paper gives a theoretical description of this so-called wet-combustion process as described by Dietz and Weijdema. The prime object is to answer the basic question whether at any water/air injection ratio this process can be steady so that combustion does not die out. This objective justifies a number of assumptions that do not entirely correspond to physical reality, but that owe necessary for a physical reality, but that owe necessary for a tractable analytical treatment. This treatment is limited to the following idealized conditions.The process occurs in a perfectly insulated cylinder of unit cross-sectional area and infinite length.The Hudds are homogeneously distributed over the cross-section of the cylinder.Exchange of heat between the fluid phases and between fluids and matrix is instantaneous, so that in any cross-section the fluid phases are in equilibrium and the temperatures of fluids and porous matrix are the same. porous matrix are the same.Pressure chops over distances of interest are small compared with the pressure itself. (Pressure is taken to be constant.)Injection rates are constant, and a steady state has already been obtained. The second assumption implies that no segregation of liquid and gas occurs. Experimentally this might be achieved by using small-diameter tubes, where segregation is largely compensated by capillarity. SPEJ P. 145

Evolution of Disordering in SiC under High Pressure High Temperature Conditions: In-situ Powder Diffraction Study

1998 ◽  
Vol 278-281 ◽  
pp. 612-617 ◽  
Author(s):  
Bogdan F. Palosz ◽  
Svetlana Stelmakh ◽  
Stanislaw Gierlotka ◽  
M. Aloszyna ◽  
Roman Pielaszek ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Diffraction Study ◽  
Powder Diffraction ◽  
Temperature Conditions ◽  
High Pressure High Temperature

scholarly journals Study on Thermo-Hydro-Mechanical Coupling and the Stability of a Geothermal Wellbore Structure

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 649
Author(s):  
Xiaolin Huan ◽  
Gao Xu ◽  
Yi Zhang ◽  
Feng Sun ◽  
Shifeng Xue
Keyword(s):  
Effective Stress ◽  
Cold Water ◽  
Drilling Fluid ◽  
Water Injection ◽  
Coupled Model ◽  
In Situ Stress ◽  
Excess Pore Pressure ◽  
Mechanical Coupling ◽  
Open Hole ◽  
Cement Sheath

For processes such as water injection in deep geothermal production, heat transfer and fluid flow are coupled and affect one another, which leads to numerous challenges in wellbore structure safety. Due to complicated wellbore structures, consisting of casing, cement sheaths, and formations under high temperature, pressure, and in situ stress, the effects of thermo-hydro-mechanical (THM) coupling are crucial for the instability control of geothermal wellbores. A THM-coupled model was developed to describe the thermal, fluid, and mechanical behavior of the casing, cement sheath, and geological environment around the geothermal wellbore. The results show that a significant disturbance of effective stress occurred mainly due to the excess pore pressure and temperature changes during cold water injection. The effective stress gradually propagated to the far-field and disrupted the integrity of the wellbore structure. A serious thermal stress concentration occurred at the junction of the cased-hole and open-hole section. When the temperature difference between the injected water and the formation was up to 160 °C, the maximum hoop tensile stress in the granite formation reached up to 43.7 MPa, as high as twice the tensile strength, which may increase the risk of collapse or rupture of the wellbore structure. The tensile radial stress, with a maximum of 31.9 MPa concentrated at the interface between the casing and cement sheath, can cause the debonding of the cementing sheath. This study provides a reference for both the prediction of THM responses and the design of drilling fluid density in geothermal development.

Nanotechnology Helps Decrease Pressure, Increase Injection in Offshore China Oil Field

2021 ◽  
Vol 73 (09) ◽  
pp. 58-59
Author(s):  
Chris Carpenter
Keyword(s):  
Water Injection ◽  
Injection Pressure ◽  
Gas Production ◽  
Oil Field ◽  
Water Flooding ◽  
Injection System ◽  
Bohai Bay ◽  
Reservoir Properties ◽  
Positive Effects ◽  
Offshore Technology

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 30407, “Case Study of Nanopolysilicon Materials’ Depressurization and Injection-Increasing Technology in Offshore Bohai Bay Oil Field KL21-1,” by Qing Feng, Nan Xiao Li, and Jun Zi Huang, China Oilfield Services, et al., prepared for the 2020 Offshore Technology Conference Asia, originally scheduled to be held in Kuala Lumpur, 2–6 November. The paper has not been peer reviewed. Copyright 2020 Offshore Technology Conference. Reproduced by permission. Nanotechnology offers creative approaches to solve problems of oil and gas production that also provide potential for pressure-decreasing application in oil fields. However, at the time of writing, successful pressure-decreasing nanotechnology has rarely been reported. The complete paper reports nanopolysilicon as a new depressurization and injection-increasing agent. The stability of nanopolysilicon was studied in the presence of various ions, including sodium (Na+), calcium (Ca2+), and magnesium (Mg2+). The study found that the addition of nanomaterials can improve porosity and permeability of porous media. Introduction More than 600 water-injection wells exist in Bohai Bay, China. Offshore Field KL21-1, developed by water-flooding, is confronted with the following challenges: - Rapid increase and reduction of water-injection pressure - Weak water-injection capacity of reservoir - Decline of oil production - Poor reservoir properties - Serious hydration and expansion effects of clay minerals To overcome injection difficulties in offshore fields, conventional acidizing measures usually are taken. But, after multiple cycles of acidification, the amount of soluble substances in the rock gradually decreases and injection performance is shortened. Through injection-performance experiments, it can be determined that the biological nanopolysilicon colloid has positive effects on pressure reduction and injection increase. Fluid-seepage-resistance decreases, the injection rate increases by 40%, and injection pressure decreases by 10%. Features of Biological Nanopolysilicon Systems The biological nanopolysilicon-injection system was composed of a bioemulsifier (CDL32), a biological dispersant (DS2), and a nanopolysilicon hydrophobic system (NP12). The bacterial strain of CDL32 was used to obtain the culture colloid of biological emulsifier at 37°C for 5 days. DS2 was made from biological emulsifier CDL32 and some industrial raw materials described in Table 1 of the complete paper. Nanopolysilicon hydrophobic system NP12 was composed of silicon dioxide particles. The hydrophobic nanopolysilicons selected in this project featured particle sizes of less than 100 nm. In the original samples, a floc of nanopolysilicon was fluffy and uniform. But, when wet, nanopolysilicon will self-aggregate and its particle size increases greatly. At the same time, nanopolysilicon features significant agglomeration in water. Because of its high interface energy, nanopolysilicon is easily agglomerated, as shown in Fig. 1.

A Proxy Flow Modelling Workflow to Estimate Gridded Dynamic Properties and Well Production Rates by Deep Learning Algorithms

2021 ◽  
Author(s):  
Soumi Chaki ◽  
Yevgeniy Zagayevskiy ◽  
Terry Wong
Keyword(s):  
Neural Network ◽  
Deep Learning ◽  
Dynamic Properties ◽  
Reservoir Management ◽  
Flow Modeling ◽  
Static Properties ◽  
Production Rates ◽  
Reservoir Properties ◽  
Well Production ◽  
Reservoir Simulator

Abstract This paper proposes a deep learning-based framework for proxy flow modeling to predict gridded dynamic petroleum reservoir properties (like pressure and saturation) and production rates for wells in a single framework. It approximates the solution of a full physics-based numerical reservoir simulator, but runs much more rapidly, allowing users to generate results for a much wider range of scenarios in a given time than could be done with a full physics simulator. The proxy can be used for reservoir management tasks like history matching, uncertainty quantification, and field development optimization. A deep-learning based methodology for accurate proxy-flow modeling is presented which combines U-Net (a variant of convolutional neural network) to predict gridded dynamic properties and deep neural network (DNN) models to forecast well production rates. First, gridded dynamic properties, such as reservoir pressure and phase saturations, are predicted from static properties like reservoir rock porosity and absolute permeability using a U-Net. Then, the static properties and the dynamic properties predicted by the U-Net are input to a DNN to predict production rates at the well perforations. The inclusion of U-net predicted pressure and saturations improves the quality of the well rate predictions. The proposed methodology is presented with the synthetic Brugge reservoir discretized into grid blocks. The U-Net input consists of three properties: dynamic gridded reservoir properties (such as pressure or fluid saturation) at the current state, static gridded porosity, and static gridded permeability. The U-Net has only one output property, the target gridded property (such as pressure or saturation) at the next time step. Training and testing datasets are generated by running 13 full physics flow simulations and dividing them in a 12:1 ratio. Nine U-Net models are calibrated to predict pressures/saturations, one for each of the nine grid layers present in the Brugge model. These outputs are then concatenated to obtain the complete pressure/saturation model for all nine layers. The constructed U-Net models match the distributions of generated pressures/saturations of the numerical reservoir simulator with a correlation coefficient value of approximately 0.99 and above 95% accuracy. The DNN models approximate well production rates accurately from U-Net predicted pressures and saturations along with static properties like transmissibility and horizontal permeability. For each well and each well perforation, the production rate is predicted with the DNN model. The use of the constructed proxy flow model generates reservoir predictions within a few minutes compared to the hours or days typically taken by a full physics flow simulator. The direct connection that is established between the gridded static and dynamic properties of the reservoir and well production rates using U-Net and DNN models has not been presented previously. Using only a small number of runs for its training, the workflow matches the numerical reservoir simulator results with reduced computational effort. This helps reservoir engineers make informed decisions more quickly, resulting in more efficient reservoir management.

Analytical Rate-Transient Analysis and Production Performance of Waterflooded Fields with Delayed Injection Support

2021 ◽  
pp. 1-23
Author(s):  
Daniel O'Reilly ◽  
Manouchehr Haghighi ◽  
Mohammad Sayyafzadeh ◽  
Matthew Flett
Keyword(s):  
Steady State ◽  
Transient Analysis ◽  
Water Injection ◽  
Data Interpretation ◽  
Production Performance ◽  
Production Data ◽  
Reservoir Properties ◽  
Two Phase ◽  
Production Forecasting ◽  
Rate Transient Analysis

Summary An approach to the analysis of production data from waterflooded oil fields is proposed in this paper. The method builds on the established techniques of rate-transient analysis (RTA) and extends the analysis period to include the transient- and steady-state effects caused by a water-injection well. This includes the initial rate transient during primary production, the depletion period of boundary-dominated flow (BDF), a transient period after injection starts and diffuses across the reservoir, and the steady-state production that follows. RTA will be applied to immiscible displacement using a graph that can be used to ascertain reservoir properties and evaluate performance aspects of the waterflood. The developed solutions can also be used for accurate and rapid forecasting of all production transience and boundary-dominated behavior at all stages of field life. Rigorous solutions are derived for the transient unit mobility displacement of a reservoir fluid, and for both constant-rate-injection and constant-pressure-injection after a period of reservoir depletion. A simple treatment of two-phase flow is given to extend this to the water/oil-displacement problem. The solutions are analytical and are validated using reservoir simulation and applied to field cases. Individual wells or total fields can be studied with this technique; several examples of both will be given. Practical cases are given for use of the new theory. The equations can be applied to production-data interpretation, production forecasting, injection-water allocation, and for the diagnosis of waterflood-performanceproblems. Correction Note: The y-axis of Fig. 8d was corrected to "Dimensionless Decline Rate Integral, qDdi". No other content was changed.

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