Analysis of Short-Time Buildup Data for Finite-Conductivity Fractures

Rosato, Nicole; Bennett, Curtis O.; Reynolds, Albert C.; Raghavan, R.

doi:10.2118/9890-pa

“…9. Here we plot results along the lines suggested by Rosato et al 14 Again the unbroken lines represent the singlelayer solutions. The principal objective of presenting results in this manner is that the influence of communication for high C jD values is more evident when results are plotted in this manner.…”

Section: Influence Of Communicationmentioning

confidence: 99%

Response of Wells Producing Layered Reservoirs: Unequal Fracture Length

Camacho-V.

¹

,

Raghavan

²

,

Reynolds

³

1987

SPE Formation Evaluation

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The response of fractured wells producing noncommunicating layered reservoirs is the focus of this work. The conductivity of the fracture is assumed to be finite. The fracture length is assumed to vary from layer to layer. Two modes of production-constant wellbore pressure and constant rate-are considered.In the first part, the fractures are assumed to communicate only at the wellbore. The results given in this section are intended to provide engineers with analytical capabilities to examine responses in wells where the layers that have been stimulated are separated by considerable distances. Procedures to interpret the results of pressure buildup and/or production tests (draw down responses) in terms of layer properties are presented. Criteria to ensure maximum productivity are specified. The second part examines well responses when the fractures are in communication at points other than the wellbore. All other things being identical, we show that communication between fractures increases productivity.

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“…[12][13][14][15] In general, the transient pressure response of a horizontal well draining a homogeneous, infinite acting reservoir depends on the location and length of the well. However, in an ideal case three main flow regimes can be detected, i.e., radial vertical flow, linear flow in the vertical plane, and pseudo-radial flow in the horizontal plane at late time.…”

Section: Dual-porosity Behaviormentioning

confidence: 99%

Transient Dual-Porosity Behavior for Horizontal Wells Draining Heterogeneous Reservoirs

Verga¹,

Beretta²,

Albani³

2001

Proceedings of SPE Western Regional Meeting

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn the literature it has been shown that a bilinear flow regime, characterized by a quarter slope line on the logarithmic derivative diagnostic plot, can arise for horizontal wells draining fractured or layered reservoirs with transient dualporosity behavior during the intermediate linear flow period. In the case of layered reservoirs the bilinear flow is a result of the linear flow in the more permeable layer toward the well and of the linear flow from the less permeable layer by which the more permeable layer is fed. In the case of fractured reservoirs the bilinear flow occurs as a result of the linear flow in the fracture planes and of the linear flow from the matrix toward the fractures. Therefore, bilinear flow is expected to end in relatively short times. However, bilinear flow was also observed for a long period in the case of two horizontal wells draining a layered, heterogeneous limestone reservoir. The reservoir is characterized by matrix porosity only but highly permeable subvertical zones have been detected due to consistent mud losses occurred during well drilling, and by well logging. The two wells are drilled in the more permeable layer of the depositional sequence encountered at each well location. A 3D numerical model of the reservoir was set up accounting for reservoir heterogeneity in an attempt to reproduce the pressure trend observed during well tests, which consistently showed a quarter slope pressure derivative. Results showed that the vertical heterogeneity would not lead to a bilinear flow regime although the permeability contrast between layers could locally exceed two orders of magnitude, probably because such contrast would not keep constant throughout the reservoir. The quarter slope pressure derivative could only be reproduced when the horizontal heterogeneity was accounted for, assuming that the more permeable subvertical zones would intersect the whole oil-bearing formation.

show abstract

“…[12][13][14][15] In general, the transient pressure response of a horizontal well draining a homogeneous, infinite acting reservoir depends on the location and length of the well. However, in an ideal case three main flow regimes can be detected, i.e., radial vertical flow, linear flow in the vertical plane, and pseudo-radial flow in the horizontal plane at late time.…”

Section: Dual-porosity Behaviormentioning

confidence: 99%

Transient Dual-Porosity Behavior for Horizontal Wells Draining Heterogeneous Reservoirs

Verga

¹

,

Beretta²,

Albani³

2001

SPE Western Regional Meeting

View full text Add to dashboard Cite

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn the literature it has been shown that a bilinear flow regime, characterized by a quarter slope line on the logarithmic derivative diagnostic plot, can arise for horizontal wells draining fractured or layered reservoirs with transient dualporosity behavior during the intermediate linear flow period. In the case of layered reservoirs the bilinear flow is a result of the linear flow in the more permeable layer toward the well and of the linear flow from the less permeable layer by which the more permeable layer is fed. In the case of fractured reservoirs the bilinear flow occurs as a result of the linear flow in the fracture planes and of the linear flow from the matrix toward the fractures. Therefore, bilinear flow is expected to end in relatively short times. However, bilinear flow was also observed for a long period in the case of two horizontal wells draining a layered, heterogeneous limestone reservoir. The reservoir is characterized by matrix porosity only but highly permeable subvertical zones have been detected due to consistent mud losses occurred during well drilling, and by well logging. The two wells are drilled in the more permeable layer of the depositional sequence encountered at each well location. A 3D numerical model of the reservoir was set up accounting for reservoir heterogeneity in an attempt to reproduce the pressure trend observed during well tests, which consistently showed a quarter slope pressure derivative. Results showed that the vertical heterogeneity would not lead to a bilinear flow regime although the permeability contrast between layers could locally exceed two orders of magnitude, probably because such contrast would not keep constant throughout the reservoir. The quarter slope pressure derivative could only be reproduced when the horizontal heterogeneity was accounted for, assuming that the more permeable subvertical zones would intersect the whole oil-bearing formation.

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Analysis of Short-Time Buildup Data for Finite-Conductivity Fractures

Cited by 10 publications

References 6 publications

Response of Wells Producing Layered Reservoirs: Unequal Fracture Length

Response of Wells Producing Layered Reservoirs: Unequal Fracture Length

Transient Dual-Porosity Behavior for Horizontal Wells Draining Heterogeneous Reservoirs

Transient Dual-Porosity Behavior for Horizontal Wells Draining Heterogeneous Reservoirs

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