Oil-Water Two Phase Flow Model Considering Threshold Pressure Gradient

2012 ◽  
Vol 594-597 ◽  
pp. 2490-2494
Author(s):  
Yi Kun Liu ◽  
Shuang Liang ◽  
Xin Wan ◽  
Yang Xuan
Keyword(s):  
Fluid Flow ◽  
Pressure Gradient ◽  
Pressure Distribution ◽  
Flow Model ◽  
Threshold Pressure ◽  
Formation Pressure ◽  
Two Phase ◽  
Threshold Pressure Gradient ◽  
Well Spacing ◽  
Oil Water

Base on the non-Darcy flow problem in low permeability reservoirs, the oil-water two phase radial fluid flow model considering threshold pressure gradient is established, the output and formation pressure distribution formulas are obtained，the production variation rule and the influence threshold pressure gradient on formation pressure distribution of different permeability and different well spacing are discussed, the reasonable well spacing of different threshold pressure gradient is calculated. Research shows that, the smaller the permeability, the bigger the corresponding threshold pressure gradient, the faster the production shortfall; in the same permeability, the greater the well spacing, the less the output; the fluid flow requires energy expenditure to overcome threshold pressure gradient, the smaller the permeability, the greater the resistance, the faster the formation pressure descent near wellbore. The reasonable well spacing for effective production is obtained by output formula, which provides the scientific foundation for improving the development effects.

scholarly journals Division Method and Seepage Law of Seepage Channels in a Tight Reservoir

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Zhenkai Wu ◽  
Feifei Fang ◽  
Xizhe Li ◽  
Hanmin Xiao ◽  
Xuewei Liu ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Early Stage ◽  
Stress Sensitivity ◽  
Phase Flow ◽  
Threshold Pressure ◽  
Two Phase ◽  
Threshold Pressure Gradient ◽  
Tight Reservoir ◽  
Oil Water ◽  
Seepage Law

Tight oil reservoirs are characterized by a low porosity, low permeability, and strong heterogeneity. The macropores, throats, and microcracks in reservoirs are the main seepage channels, which affect the seepage law in the reservoirs. In particular, oil-water two-phase flow in different types of pores requires further study. In this study, two groups of online NMR displacement experiments were designed to study the seepage characteristics of tight oil reservoirs. It was found that the main seepage channels for oil-water two-phase flow are the microcracks, large pores, and throats in the reservoir. The large pores are mainly micron and submicron scale in size. The oil in the small pores is only transferred to the large pores through imbibition to participate in the flow, and there is no two-phase flow. Based on the influence of different pore structures on the seepage law of a tight reservoir, the pores were divided into seepage zones, and a multistage seepage model for tight reservoirs was established. Based on this model, the effects of the imbibition, stress sensitivity, threshold pressure gradient, and Jamin effect on model’s yield were studied. The results show that imbibition is no longer effective after a while. Owing to the stress sensitivity, the threshold pressure gradient, and the Jamin effect, oil production will be reduced. As the parameter value increases, the oil production decreases. The production decreases rapidly in the early stage of mining while decreases slowly in the later stage, exhibiting a trend of high yield in the early stage and stable yield in the later stage.

Transient Coupled Borehole/Formation Fluid-Flow Model for Interpretation of Oil/Water Production Logs

SPE Journal ◽  
2016 ◽  
Vol 22 (01) ◽  
pp. 389-406 ◽  
Author(s):  
Amir Frooqnia ◽  
Carlos Torres-Verdín ◽  
Kamy Sepehrnoori ◽  
Rohollah Abdhollah-Pour
Keyword(s):  
Fluid Flow ◽  
Flow Model ◽  
Volume Fraction ◽  
Fluid Phase ◽  
Coupling Method ◽  
Average Pressure ◽  
Petrophysical Properties ◽  
Two Phase ◽  
Flow Models ◽  
Oil Water

Summary Interpretation of two-phase production logs (PLs) traditionally constructs borehole fluid-flow models decoupled from the physics of reservoir rocks. However, quantifying formation dynamic petrophysical properties from PLs requires simultaneous modeling of both borehole and formation fluid-flow phenomena. This paper develops a novel transient borehole/formation fluid-flow model that allows quantification of the effect of formation petrophysical properties on measurements acquired with production-logging tools (PLTs). We invoke a 1D, isothermal, two-fluid formulation to simulate borehole fluid-phase velocity, pressure, volume fraction, and density in oil/water-flow systems. The developed borehole fluid-flow model implements oil-dominant and water-dominant bubbly flow regimes with the inversion point taking place approximately when the oil volume fraction is equal to 0.5. Droplet diameter is dynamically modified to simulate interfacial drag effects, and to effectively account for variations of slip velocity in the borehole. Subsequently, a new successive iterative method interfaces the borehole and formation fluid-flow models by introducing appropriate source terms into the borehole fluid-phase mass-conservation equations. The novel iterative coupling method integrated with the developed borehole fluid-flow model allows dynamic modification of reservoir boundary conditions to accurately simulate transient behavior of borehole crossflow taking place across differentially depleted rock formations. In the case of rapid variations of near-borehole properties, frequent borehole/formation communication inevitably increases the computational time required for fluid-flow simulation. Despite this limitation, in a two-layer reservoir model penetrated by a vertical borehole, the coupling method accurately quantifies a 14% increase of volume-averaged oil-phase relative permeability of the low-pressure layer caused by through-the-borehole cross-communication of differentially depleted layers. Sensitivity analyses indicate that the alteration of near-borehole petrophysical properties primarily depends on formation average pressure, fluid-phase density contrast, and borehole-deviation angle. A practical application of the new coupled fluid-flow model is numerical simulation of borehole production measurements to estimate formation average pressure from two-phase selective-inflow-performance (SIP) analysis. This study suggests that incorporating static (shut-in) PL passes into the SIP analysis could result in misleading estimation of formation average pressure.

Numerical Simulation of Pressure Distribution between Injection and Production Well in Low Permeability Reservoir

2013 ◽  
Vol 807-809 ◽  
pp. 2554-2557
Author(s):  
Qi Han Zhang ◽  
Zi Yi Guo ◽  
Ji Peng ◽  
Ting Song Xiong ◽  
Shi Feng Xue
Keyword(s):  
Numerical Simulation ◽  
Pressure Gradient ◽  
Pressure Distribution ◽  
Low Permeability ◽  
Threshold Pressure ◽  
Production Well ◽  
Pressure System ◽  
Threshold Pressure Gradient ◽  
Low Permeability Reservoir ◽  
Pressure Sensitive

Considering the pressure-sensitive effect and threshold pressure gradient in low permeability reservoirs, a new mathematical model of the variable permeability for reservoir between injection and production well is established. The Garlerkin method is used to set up the finite element computation equations, and corresponding numerical simulation program is developed. The influence of Injection-production pressure, well spacing and hydraulic fracture are quantitative evaluation. The simulation results show that the pressure-sensitive effect and threshold pressure gradient has a strong influence on pressure distribution between injection and production wells. Establishing the effective driving pressure system is the key to improve well production of low permeability reservoir.

The Moving Boundary Movement of Vertical Fractured Well in Tight Oil Reservoir

2013 ◽  
Vol 868 ◽  
pp. 633-637
Author(s):  
Li Feng Liu ◽  
Xin Wang
Keyword(s):  
Pressure Gradient ◽  
Flow Model ◽  
Moving Boundary ◽  
Flow Characteristics ◽  
Seepage Flow ◽  
Threshold Pressure ◽  
Threshold Pressure Gradient ◽  
Tight Reservoir ◽  
Tight Reservoirs ◽  
Fractured Well

Because of the obvious non-Darcy characteristic of fluid flowing in tight reservoirs, there is a virtual moving boundary at the flow edge, and these percolation models of fractured wells with Darcy formula are no longer applicable. Based on the threshold pressure gradient effect, the unsteady seepage flow model of vertical fractured well was established in the drain area by means of Source and Green's Functions. With the flow characteristics at the boundary of tight reservoir, the motion equation of axes of moving boundary was obtained. By Example analysis, its proved that the moving boundary is approximate circular in the far-field, and it will move slower with the increase of the threshold pressure gradient.

Study on the Theory of Effective Displacement in Low Permeability Reservoir

2013 ◽  
Vol 868 ◽  
pp. 551-555
Author(s):  
Feng Jiao Wang ◽  
Yi Kun Liu ◽  
Yong Ping Wang ◽  
Chao Yang Hu
Keyword(s):  
Pressure Gradient ◽  
Injection Pressure ◽  
Optimal Choice ◽  
Oil Field ◽  
Experimental Result ◽  
Low Permeability ◽  
Threshold Pressure ◽  
Threshold Pressure Gradient ◽  
Low Permeability Reservoir ◽  
Well Spacing

Taking displacing pressure gradient and threshold pressure gradient into account, we have carried on a research of effective displacement theory in low permeability formation. Based on displacing pressure gradient expression of different production diverging/converging, we get displacing pressure gradient engraving when formational pressure, injection pressure, bottom hole producing pressure, and inter well distance is changing. And analyze its regular as well. On the basis of experimental result, establishing the relationship between threshold pressure gradient and displacing pressure gradient, and analyze the critical value of different pay zones for effective displacement. Study has shown that if we want to drive low permeability formation it is necessary that the displacing pressure gradient is larger than the threshold pressure gradient. It is the optimal choice for low permeability formations effective displacement that the well spacing should be smaller. It can achieve a goal that effective driving low permeability reservoir by the adjustment of taking measures and the injection-production pressure systems modulation. The study has important guiding significance for the development of low permeability formation, and it has got effective verification in oil field test.

scholarly journals Study on Variation Laws of Fluid Threshold Pressure Gradient in Low Permeable Reservoir

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3704
Author(s):  
Mingwei Zhao ◽  
Mengjiao Cao ◽  
Haonan He ◽  
Caili Dai
Keyword(s):  
Pressure Gradient ◽  
Physical Simulation ◽  
Two Phase Flow ◽  
Diameter Distribution ◽  
Phase Flow ◽  
Threshold Pressure ◽  
Power Functions ◽  
Pore Throat ◽  
Two Phase ◽  
Threshold Pressure Gradient

A study on the seepage characteristics and laws of nano-micron pore throat in a low permeable reservoir matrix is of great significance for promoting high efficacy of low permeable reservoirs. Threshold pressure gradient (TPG) is an essential factor to reflect the seepage law. Here, variation laws of TPG and its influencing factors of low reservoir fluid are analyzed systematically through physical simulation experiment. Throat diameter distribution of cores was measured by a mercury injection method, and it was found that with the decrease of pore throat median diameter, TPG increase appeared slowly first and fast afterwards. The patterns of the TPG with permeability in water and oil were compared. Results showed that the TPG versus permeability gave power functions in a form and the TPG in oil was more than two times larger than that of water. Besides, TPG in two-phase flow was investigated by the stabilization method. Tests revealed that the higher the oil saturation, the greater the TPG value, and the TPG in two-phase flow is always higher than that of single-phase flow under the same conditions, which function as the combined action of the capillary force. In addition, the effects of core length, fluid type, and core wettability on the TPG were studied systematically, which has guiding significance for the development of a low permeability reservoir.

Study on the Unstable Seepage Flow Model and the Productivity Characteristics in Tight Gas Heterogeneity Reservoir

2013 ◽  
Vol 868 ◽  
pp. 465-472
Author(s):  
Jia Deng ◽  
Wei Yao Zhu ◽  
Qian Ma ◽  
Huai Jian Yi
Keyword(s):  
Pressure Gradient ◽  
Gas Flow ◽  
Flow Model ◽  
Seepage Flow ◽  
Threshold Pressure ◽  
Tight Gas ◽  
Low Velocity ◽  
Threshold Pressure Gradient ◽  
Tight Gas Reservoir ◽  
Matlab Programming

In this paper, considering on the real threshold pressure gradient (TPG), the mathematical model for low velocity non-Darcy unstable gas flow was established for the tight gas reservoir. Based on the low velocity non-Darcy unstable gas flow model, the gas flow model in heterogeneity formation was developed, and the analytical solution was obtained on the condition of constant production for inner boundary. Then we calculated the model numerically by Matlab programming. Its analyzed that the pressure distribution and the influencing factors such as production rate, producing time, reservoir thickness and the threshold pressure gradient. We compared the heterogeneity formation with the homogeneous formation by the heterogeneity low velocity non-Darcy unstable gas flow model, which shows great difference and illustrate the significance of research on heterogeneity.

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