Flowback Performance in Intensely Naturally Fractured Shale Gas Reservoirs

Crafton, Jim

doi:10.2118/131785-ms

Cited by 32 publications

(9 citation statements)

References 9 publications

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“…They emphasize the need to analyze early-stage single-phase data associated with flow through the hydraulic fracture to derive properties such as hydraulic-fracture conductivity. Crafton and his coauthors have authored several papers dedicated to quantitative flowback analysis, which served as an important starting point for this work (Crafton 1998(Crafton , 2008(Crafton , 2010Gunderson 2006, 2007).…”

Section: Introductionmentioning

confidence: 99%

Modeling Two-Phase Flowback of Multifractured Horizontal Wells Completed in Shale

2013

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Early fluid production and flowing pressure data gathered immediately after fracture stimulation of multifractured horizontal wells may provide an early opportunity to generate long-term forecasts in shale-gas (and other hydraulically fractured) reservoirs. These early data, which often consist of hourly (if not more frequent) monitoring of fracture/formation fluid rates, volumes, and flowing pressures, are gathered on nearly every well that is completed. Additionally, fluid compositions may be monitored to determine the extent of load fluid recovery, and chemical tracers added during stage treatments to evaluate inflow from each of the stages. There is currently debate within the industry of the usefulness of these data for determining the long-term production performance of the wells. "Rules of thumb" derived from the percentage of load-fluid recovery are often used by the industry to provide a directional indication of well performance. More-quantitative analysis of the data is rarely performed; it is likely that the multiphase-flow nature of flowback and the possibility of early data being dominated by wellbore-storage effects have deterred many analysts.In this work, the use of short-term flowback data for quantitative analysis of induced-hydraulic-fracture properties is critically evaluated. For the first time, a method for analyzing water and gas production and flowing pressures associated with the flowback of shale-gas wells, to obtain hydraulic-fracture properties, is presented. Previous attempts have focused on single-phase analysis. Examples from the Marcellus shale are analyzed. The short (less than 48 hours) flowback periods were followed by long-term pressure buildups (approximately 1 month). Gas þ water production data were analyzed with analytical simulation and rate-transient analysis methods designed for analyzing multiphase coalbedmethane (CBM) data. This analogy is used because two-phase flowback is assumed to be similar to simultaneous flow of gas and water during long-term production through the fracture system of coal. One interpretation is that the early flowback data correspond to wellbore þ fracture volume depletion (storage). It is assumed that fracture-storage volume is much greater than wellbore storage. This flow regime appears consistent with what is interpreted from the long-term pressure-buildup data, and from the rate-transient analysis of flowback data. Assuming further that the complex fracture network created during stimulation is confined to a region around perforation clusters in each stage, one can see that fluid-production data can be analyzed with a two-phase tankmodel simulator to determine fracture permeability and drainage area, the latter being interpreted to obtain an effective (producing) fracture half-length given geometrical considerations. Total fracture half-length, derived from rate-transient analysis of online (post-cleanup) data, verifies the flowback estimates. An analytical forecasting tool that accounts for multiple sequences of post-storage linear flow, f...

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Section: Introductionmentioning

confidence: 99%

Modeling Two-Phase Flowback of Multifractured Horizontal Wells Completed in Shale

2013

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“…The reason for the use of large volumes is the fact that slickwater does not have enough viscosity to be able to suspend high concentration of sand/proppants. Other reports claim that the use of these large volumes of water is necessary to produce a complex fracture network (Crafton 2010;Chong et al 2010;Zanganeh et al 2014). In any case, the fate of this water is not known as it has been reported that only 10 to 20% of the injected water is recovered during the flowback of these wells (King 2012).…”

Section: Flowback Of Fracturing Watermentioning

confidence: 99%

“…Many factors can affect the flowback after fracturing job, such as pumping schedule, fluid type and the fracturing fluid chemistry (polymer loading, cross linkers and breakers). Flowback rates and characteristics can be used to estimate some of the fracture properties (Crafton 2010;Williams-Kovacs and Clarckson 2013;Alkouh et al 2013).…”

Section: Flowback Of Fracturing Watermentioning

confidence: 99%

Required Understanding for the Development of Shale Reservoirs in the Middle East in Light of Developments in North America

Sayed¹,

Al-Muntasheri²,

Li³

2015

SPE Middle East Unconventional Resources Conference and Exhibition

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“…Careful management of flowback procedure is crucial to (1) obtain accurate physical and chemical data measurements and (2) prevent damage to the stimulated well (Crafton, 2008(Crafton, , 2010 and (3) improve well clean-p and maximize load recovery (Crafton, 1998). Accurate data ensures representative flowback volumetric, rate + pressure transient, and chemical analyses.…”

Section: Spe 167164mentioning

confidence: 99%

Understanding Flowback as a Transient 2-Phase Displacement Process: An Extension of the Linear Dual-Porosity Model

Ezulike

Dehghanpour

Hawkes³

2013

All Days

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Existing rate transient models for fractured horizontal wells assume single-phase fluid flow. This assumption is violated in early times, when hydraulic fractures (HF) are filled with fracturing water and hydrocarbon. This calls for a model that captures the transient 2-phase (gas/oil + water) flow in HF, and can be used for history matching rate and pressure data measured during flowback operations. Existing models for analysing multiphase data from solution-gas drive and high-water-saturation conventional reservoirs cannot be applied to flowback data because of simplifying assumptions such as (1) constant average phase saturation with time, (2) constant rate or pressure well constraint and (3) radial flow. This paper extends the existing linear dual-porosity model (DPM) and develops a flowback analysis model (FAM) which accounts for transient multiphase flow in HF.The proposed model adopts an explicit dynamic-relative-permeability (DRP) function of time for hydrocarbon phase in the fracture network to account for water-saturation drop. This model assumes that water-saturation drop with time causes a corresponding non-linear increase in hydrocarbon relative-permeability in HF. The DRP function is obtained from analysing cumulative hydrocarbon + water measured during flowback operation and drainage relative-permeability curves from existing literature. Fifteen tight oil, tight gas and shale gas wells completed in the Bluesky, Cardium, Evie, Muskwa and Otter-Park Formations were used for this study. The resulting DRP parameters control the rate of water-saturation drop in HF (clean-up rate). DRP is incorporated into the existing DPM to obtain FAM flow equations. This paper attempt solving these equations with Mellin transforms under variable bottom-hole rate and pressure well constraints.FAM converges to the existing DPM at the limit of residual water-saturation. DRP captures the fluid physics from flowback phase till the "full" hydrocarbon production phase in the life of a multifractured horizontal well. The application of FAM on transient 2-phase flowback data (rate + pressure) could help estimate key reservoir parameters (e.g. effective HF half-length) and evaluate flowback performance (e.g. percentage of total inject fluid left in HF and matrix and the speed of HF clean-up). Results from this study is applicable for interpreting 2-phase flowback data from multi-fractured horizontal wells completed in tight and shale reservoirs. This study allows the industry to forecast hydrocarbon recovery from flowback data and estimate/predict the effectiveness of flowback operations. SPE 167164Careful management of flowback procedure is crucial to (1) obtain accurate physical and chemical data measurements and (2) prevent damage to the stimulated well (Crafton, 2008(Crafton, , 2010 and (3) improve well clean-p and maximize load recovery (Crafton, 1998). Accurate data ensures representative flowback volumetric, rate + pressure transient, and chemical analyses. These analyses provide (1) important well and reservoir informat...

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Flowback Performance in Intensely Naturally Fractured Shale Gas Reservoirs

Cited by 32 publications

References 9 publications

Modeling Two-Phase Flowback of Multifractured Horizontal Wells Completed in Shale

Modeling Two-Phase Flowback of Multifractured Horizontal Wells Completed in Shale

Required Understanding for the Development of Shale Reservoirs in the Middle East in Light of Developments in North America

Understanding Flowback as a Transient 2-Phase Displacement Process: An Extension of the Linear Dual-Porosity Model

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