A Study of Transversely vs Longitudinally Fractured Horizontal Wells in a Moderate-Permeability Gas Reservoir

Liu, Tianyu; Marongiu-Porcu, Matteo; Ehlig-Economides, Christine; Economides, Michael J.

doi:10.2118/163317-ms

Cited by 7 publications

(1 citation statement)

References 9 publications

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“…Also shown in Fig. 24b (Menchaca 2014) is a stress-orientation map of the South Texas Eagle Ford play.…”

Section: Case-histories Studymentioning

confidence: 99%

Performance Comparison of Transversely and Longitudinally Fractured Horizontal Wells Over Varied Reservoir Permeability

Yang

2016

SPE Journal

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Since the late 1980s when Maersk published their work on multiple fracturing of horizontal wells in the Dan field, the use of transverse multiple-fractured horizontal wells has become the completion of choice and the "industry standard" for unconventional and tight-oil and tight-gas reservoirs. Today, approximately 60% of all wells drilled in the United States are drilled horizontally, and nearly all are multiple-fractured. However, little work has been performed to address and understand the relationship between the principal stresses and the lateral direction. This paper has as its goal to fundamentally address the questions: In which direction should I drill my lateral? Do I drill it in the direction of the maximum horizontal stress (longitudinal), or do I drill it in the direction of the minimum horizontal stress (transverse)?This work focuses on how the horizontal well's lateral direction (longitudinal or transverse fracture orientation) influences productivity, reserves, and economics of horizontal wells. Optimization studies, with a single-phase fully 3D numerical simulator including convergent non-Darcy flow, were used to highlight the importance of lateral direction as a function of reservoir permeability. The simulations, conducted for both oil and gas formations over a wide range of reservoir permeability (50 nd-5 md), compare and contrast the performance of transversely multiplefractured horizontal wells with longitudinally fractured horizontal wells in terms of rate, recovery, and economics. This work also includes a series of field case studies to illustrate actual field comparisons of longitudinal vs. transverse horizontal well performance in both oil and gas reservoirs, and to tie these field examples to the numerical-simulation study. Further, the effects of lateral length, fracture half-length, and fracture conductivity were investigated to see how these parameters affect the decision of lateral direction in both oil and gas reservoirs. In addition, this study seeks to address how completion style (openhole or cased-hole completion) affects the selection of lateral direction.The results show the existence of a critical reservoir permeability, above which longitudinal fractured horizontal wells outperform transverse fractured horizontal wells. With openhole completions, the critical permeability is 0.04 md for gas reservoirs and 0.4 md for oil reservoirs. With cased-hole completions, longitudinal horizontal wells are preferred at a reservoir permeability above 1.5 md in gas reservoirs, and transverse horizontal wells are preferable over the entire permeability range of this study (50 nd-5 md) in oil reservoirs. These are new findings. Previous work generally suggested that longitudinal horizontal wells are a better option for gas reservoirs with permeability over 0.5 md, and for oil reservoirs with permeability over 10 md.This work extends prior study to include unconventional reservoir permeabilities. It provides critical permeability values for both gas and oil reservoirs, which are validated b...

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“…Also shown in Fig. 24b (Menchaca 2014) is a stress-orientation map of the South Texas Eagle Ford play.…”

Section: Case-histories Studymentioning

confidence: 99%

Performance Comparison of Transversely and Longitudinally Fractured Horizontal Wells Over Varied Reservoir Permeability

Yang

2016

SPE Journal

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Case studies for the fracturing of highly diverse gas reservoirs

Ajao

Iwu

Dalamarinis

et al. 2013

Journal of Natural Gas Science and Engineering

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Case Studies for the Fracturing of Highly Diverse Gas Reservoirs

Ajao¹,

Iwu²,

Dalamarinis³

et al. 2013

All Days

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Hydraulic fracturing, which has emerged as the premier well completion technology in the petroleum industry, is applied to almost all natural gas wells, worldwide, but for different reasons. It may sound trite but all gas fields should be considered as "unconventional, compared to oil wells." In higher-permeability reservoirs (> 5 md) the remediation of reservoir-to-well turbulence is the main motivation. In lower-permeability reservoirs the main rationale is similar to oil- stimulation- but with significant adjustments. In much tighter reservoirs, including shales, the purpose is to inundate the formation with a very large number of parallel fractures, executed transversely from horizontal wells. This would lead to the effective draining of the Stimulated Reservoir Volume (SRV). We present here two complete field studies, one in a 17 md dry gas well in Siberia, and the second from a 0.0001 md shale formation in the United States. The shale formation is assumed to have a number of similar properties with the field data from the 17md gas well. The first study shows the impact of turbulence and its removal via hydraulic fracturing. We also show the management of inside-the-fracture turbulence through the adjustment of fracture geometry and the selection of higher permeability proppant. The design approach uses the Unified Fracture Design (UFD), which is the only way to adjust fracture geometry based on expected flow performances. The drainage shape and the irregular ratio between reservoir length and fracture spacing are important considerations in SRV. We also conduct a parametric study on the turbulence effects inside the fractures for a range of reservoir permeabilities. Which design/execution constraints are necessary at very low or very high permeabilities? For the shale reservoir, while turbulence effects appear to be inconsequential, the length of the fracture, the spacing among fractures and the actual number of fractures are the critical variables for the physical production optimization. Such a study is also presented in this paper.

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A Study of Transversely vs Longitudinally Fractured Horizontal Wells in a Moderate-Permeability Gas Reservoir

Cited by 7 publications

References 9 publications

Performance Comparison of Transversely and Longitudinally Fractured Horizontal Wells Over Varied Reservoir Permeability

Performance Comparison of Transversely and Longitudinally Fractured Horizontal Wells Over Varied Reservoir Permeability

Case studies for the fracturing of highly diverse gas reservoirs

Case Studies for the Fracturing of Highly Diverse Gas Reservoirs

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