High-Resolution Visualization of Flow Interference Between Frac Clusters (Part 1): Model Verification and Basic Cases

Weijermars, Ruud; Harmelen, Arnaud van; Zuo, Lihua; Nascentes, Ibere Alves; Yu, Wei

doi:10.15530/urtec-2017-2670073a

Cited by 19 publications

(33 citation statements)

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“…For simple reservoir models especially if it is homogeneous porous medium and simple injectors and producers placement as shown in Figure 4, an alternative, analytical streamline method can be applied to compute FP and TOF [13,[42][43][44][45]. The analytical streamline method is based on complex potentials and calculates the flow velocity using the strength/locations of the point source (injectors) and sinks (producers) by the following formula [13]:…”

Section: Numerical Model Verificationmentioning

confidence: 99%

Rules for Flight Paths and Time of Flight for Flows in Porous Media with Heterogeneous Permeability and Porosity

Zuo

Weijermars

2017

Geofluids

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Porous media like hydrocarbon reservoirs may be composed of a wide variety of rocks with different porosity and permeability. Our study shows in algorithms and in synthetic numerical simulations that the flow pattern of any particular porous medium, assuming constant fluid properties and standardized boundary and initial conditions, is not affected by any spatial porosity changes but will vary only according to spatial permeability changes. In contrast, the time of flight along the streamline will be affected by both the permeability and porosity, albeit in opposite directions. A theoretical framework is presented with evidence from flow visualizations. A series of strategically chosen streamline simulations, including systematic spatial variations of porosity and permeability, visualizes the respective effects on the flight path and time of flight. Two practical rules are formulated. Rule 1 states that an increase in permeability decreases the time of flight, whereas an increase in porosity increases the time of flight. Rule 2 states that the permeability uniquely controls the flight path of fluid flow in porous media; local porosity variations do not affect the streamline path. The two rules are essential for understanding fluid transport mechanisms, and their rigorous validation therefore is merited.

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Section: Numerical Model Verificationmentioning

confidence: 99%

Rules for Flight Paths and Time of Flight for Flows in Porous Media with Heterogeneous Permeability and Porosity

Zuo

Weijermars

2017

Geofluids

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“…Investigations of how hydraulic fractures drain the matrix in shale reservoirs are also possible using our method for streamline simulation and fluid time-of-flight tracing based on complex analysis methods. Applications include the visualization of hydrocarbon migration toward hydraulically fractured wells [9], and fluid drainage near multi-fractured horizontal wells with fracture hits [8,74,81]. The key algorithms and key workflow steps used in our model method are explained below.…”

Section: Methodsmentioning

confidence: 99%

“…Exactly how much drainage occurs, and where the fluid produced in fractured wells comes from, can be visualized with our method at a high resolution [8]. Our present approach applies calculus from complex analysis to provide closed-form solutions for single phase flow involving an unlimited number of interacting fractures [9].…”

Section: Drained Rock Volumementioning

confidence: 99%

“…The complex potential for N interval-sources, each with their own angle βk, centre zck, length Lk and strength mk, reads [8]:…”

Section: Interval Sourcementioning

confidence: 99%

“…We developed a grid-less and meshless model tool based on Complex Analysis Methods (CAM), which allows rapid visualization of flow attributes around individual hydraulic fractures, using: (1) pressure field contour plots, (2) velocity field contour plots, (3) streamlines, and (4) drainage contours. The accuracy of the CAM tool has been benchmarked against independent reservoir simulators, which showed no discernable difference in results [6][7][8], except for the higher resolution of the CAM results. The method is suitable for modeling the drainage pattern near multiple hydraulic fractures and natural fractures.…”

Section: Introductionmentioning

confidence: 99%

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Shale Reservoir Drainage Visualized for a Wolfcamp Well (Midland Basin, West Texas, USA)

Weijermars¹,

Harmelen²

2018

Energies

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Closed-form solution-methods were applied to visualize the flow near hydraulic fractures at high resolution. The results reveal that most fluid moves into the tips of the fractures. Stranded oil may occur between the fractures in stagnant flow zones (dead zones), which remain outside the drainage reach of the hydraulic main fractures, over the economic life of the typical well (30-40 years). Highly conductive micro-cracks would further improve recovery factors. The visualization of flow near hypothetical micro-cracks normal to the main fractures in a Wolfcamp well shows such micro-cracks support the recovery of hydrocarbons from deeper in the matrix, but still leave matrix portions un-drained with the concurrent fracture spacing of 60 ft (~18 m). Our study also suggests that the traditional way of studying reservoir depletion by mainly looking at pressure plots should, for hydraulically fractured shale reservoirs, be complemented with high resolution plots of the drainage pattern based on time integration of the velocity field.

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Visualization of drained rock volume (DRV) in hydraulically fractured reservoirs with and without natural fractures using complex analysis methods (CAMs)

Khanal

Weijermars

2019

Pet. Sci.

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The drainage areas (and volumes) near hydraulically fractured wells, computed and visualized in our study at high resolution, may be critically affected by the presence of natural fractures. Using a recently developed algorithm based on complex analysis methods (CAMs), the drained rock volume (DRV) is visualized for a range of synthetic constellations of natural fractures near hydraulic fractures. First, flow interference effects near a single hydraulic fracture are systematically investigated for a variety of natural fracture sets. The permeability contrast between the matrix and the natural fractures is increased stepwise in order to better understand the effect on the DRV. Next, a larger-scale model investigates flow interference for a full hydraulically fractured well with a variety of natural fracture sets. The time of flight contours (TOFCs) outlining the DRV are for all cases with natural fractures compared to a base case without any natural fractures. Discrete natural fractures, with different orientations, hydraulic conductivity, and fracture density, may shift the TOFC patterns in the reservoir region drained by the hydraulically fractured well, essentially shifting the location of the well's drainage area. The CAM-based models provide a computationally efficient method to quantify and visualize the drainage in both naturally and hydraulically fractured reservoirs. Keywords Natural fracture • Drained rock volume • Drainage area distortion • Hydraulic fractures Abbreviations CAM Complex analysis methods DRV Drained rock volume TOFC Time of flight contours SRV Stimulated reservoir volume DFN Discrete fracture network List of symbols Complex potential m Strength of point/interval sources υ Strength of the natural fractures V Velocity potential γ Tilt angle of the natural fractures x c Center of the interval source L Length of the interval source Angle of the interval source L k Total length of interval source k m k Strength of interval source k h Reservoir thickness B Formation volume factor v x Velocity in the x-direction v y Velocity in the y-direction Δt Time-step

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High-Resolution Visualization of Flow Interference Between Frac Clusters (Part 1): Model Verification and Basic Cases

Cited by 19 publications

References 0 publications

Rules for Flight Paths and Time of Flight for Flows in Porous Media with Heterogeneous Permeability and Porosity

Rules for Flight Paths and Time of Flight for Flows in Porous Media with Heterogeneous Permeability and Porosity

Shale Reservoir Drainage Visualized for a Wolfcamp Well (Midland Basin, West Texas, USA)

Visualization of drained rock volume (DRV) in hydraulically fractured reservoirs with and without natural fractures using complex analysis methods (CAMs)

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