Evaluation of Bottom Hole Pressures in 40 Soft Rock Frac-Pack Completions in 
the Gulf of Mexico

Mullen, M.E.; Stewart, B.R.; Norman, W.D.

doi:10.2523/28532-ms

Cited by 8 publications

(2 citation statements)

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“…[1][2][3] A variety of water-based fracturing fluids is in use for fracpacking. [4][5][6][7] These include linear guar-based gels such as hydroxypropyl guar, HPG, synthetic polymers such as HEC, borate cross-linked guar, and viscoelastic surfactants (VES).…”

Section: Introductionmentioning

confidence: 99%

Frac Packing in Soft Formations: Low Efficiency Fluids Exacerbate Formation Damage

McElfresh¹,

Khodaverdian²,

Baycroft³

2002

Proceedings of International Symposium and Exhibition on Formation Damage Control

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractHydraulic fracturing injection experiments were performed in unconsolidated sand under stress to delineate the mechanisms controlling fracture propagation and to determine the effect of these mechanisms on potential formation damage. The tests included injection of cross-linked guar and visco-elastic surfactant into 3-Darcy sand samples subjected to different overburden stresses. The following observations were made:• The experimental data indicate that fracture propagation in unconsolidated sand is primarily a result of fluid invasion and shear failure in a process zone ahead of the fracture tip. The shear failure is caused by large tip stresses or by pore pressure increase within the process zone.• Three different invasion/damage zones were observed, including the external filtercake, the gel-invaded zone (or the internal filtercake), and the filtrate-invaded zone.• Sub-parallel "micro fracturing" and complex fracture geometry was encountered. The sub-parallel fractures may be initiated at the tip or at the fracture wall due to shear failure and is dependent on the fluid efficiency and the type of leakoff, i.e., wall building or viscous.• Field consequences of micro fracturing during stimulation may include early screenout, short fracture length and extensive formation damage as the fracturing fluid invades the sheared interfaces.• Typically, lower efficiency fluids were associated with increased net propagation pressure and higher density of micro fracturing.These findings suggest that injection of low efficiency fluids in weak, poorly consolidated formations results in a different type of formation damage, namely creation of sub-parallel micro fractures enveloping the main propped fracture, that could severely undermine post-stimulation productivity.

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Section: Introductionmentioning

confidence: 99%

Frac Packing in Soft Formations: Low Efficiency Fluids Exacerbate Formation Damage

McElfresh¹,

Khodaverdian²,

Baycroft³

2002

Proceedings of International Symposium and Exhibition on Formation Damage Control

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“…1,2,3 Depending on the formation properties, a variety of fracturing fluids may be used in a fracpack operation, including borate cross-linked guar, linear gel, VES and nonviscous fluids. [4][5][6][7] The cross-linked fluids, because of their wall building capability, can create relatively long fractures, but may cause extensive formation damage if the polymer breakdown is incomplete following stimulation.…”

Section: Introductionmentioning

confidence: 99%

Hydraulic Fracturing Stimulation in Poorly Consolidated Sand: Mechanisms and Consequences

Khodaverdian

McElfresh

2000

Proceedings of SPE Annual Technical Conference and Exhibition

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA series of hydraulic fracturing injection experiments was performed in unconsolidated sand in a radial flow cell (RFC) to delineate the fundamental mechanisms controlling fracture propagation. The results of this work will be used to optimize the current fracpacking practices in unconsolidated and poorly consolidated sand and to develop adequate modeling techniques. Although the generic word "fracture" is used throughout this document and elsewhere to describe injectioninduced formation parting during stimulation, it will be made clear that the tip propagation mechanisms in unconsolidated sand are fundamentally different from linear elastic fracture mechanics (LEFM) as defined for competent rocks.Conceptually, the RFC used for the injection tests simulates a 1-ft thick section of unconsolidated sand formation within a 3-ft radius of a wellbore. The tests in this system included injection of cross-linked guar and visco-elastic surfactant into 3,000 md sand samples subjected to different overburden stresses. The following is a summary of the findings: • The experimental data suggest that "fracture" propagation in unconsolidated sand is primarily a result of shear failure in a process-zone ahead of the fracture tip. The shear failure is caused by large tip stresses (due to tip plasticity) and by pore pressure increase within the process zone.• Uncharacteristically large net fracturing pressures (NFP) were encountered for low-efficiency fluids. Generally, the NFP increased with decreasing fluid efficiency.• Multiple sub-parallel fracturing and complex fracture geometry was encountered. Sub-parallel fractures may be initiated at the tip or at the fracture wall due to shear failure and is dependent on the fluid efficiency and the type of leakoff, i.e., wall building or viscous. The field consequences of sub-parallel fracturing during stimulation may include premature screenout and fracture bridging, short fracture length and extensive formation damage as the fracturing fluid invades the sheared interfaces.

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Optimizing Sand Control Treatments Using Gauge Data

Jain¹,

Wassouf²,

Tibbles³

2018

SPE Asia Pacific Oil and Gas Conference and Exhibition

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While the importance of pre-job design has always been appreciated, detailed post-job evaluation of gravel pack execution data (both surface and downhole) is equally valuable as it provides a means to learn from past treatments, calibrate models, and improve future designs. Traditionally, post-job analysis has been limited to high-level pack evaluation and failure investigation but has a much wider range of applications in the confirmation of success, better understanding of downhole mechanisms and validation of simulation models. Downhole data analysis techniques can be used to isolate sections of the flow path and develop a more detailed understanding of each stage of the treatment from running in the hole (RIH) to pulling out of the hole (POOH). Detailed post-job evaluation is often skipped due to the significant effort involved in data handling as well as the lack of a defined workflow and an integrated software tool. This paper provides an overview of the evaluation and calibration of surface and downhole data along with the steps, workflow and tools required to process the data in the easiest and most efficient manner, enabling faster, more detailed and more accurate analysis of operations. Various case studies are used to demonstrate how post-job evaluation using downhole gauges can be used to efficiently analyse the various stages of the operation including wellbore displacements, reverse and circulating step rate tests and gravel packing operations. A variety of important phenomena are identified and quantified, such as friction pressures, packing mechanisms, fluid displacements, screen plugging and roping, which may otherwise be missed. The paper further illustrates how the defined workflow can maximize the likelihood of success by using post-job evaluation results to better identify and minimize risks during pre-job design stages while reducing the need for excessive safety factors within the operational window. The analysis workflows introduced here will maximize the value of downhole gauge data and serve as a reference to practicing completion engineers in the efficient processing, analysis and interpretation of post-job data. It can be used to revisit and better understand historical sand control treatments, and continuously improve future treatments.

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Evaluation of Bottom Hole Pressures in 40 Soft Rock Frac-Pack Completions in the Gulf of Mexico

Cited by 8 publications

References 0 publications

Frac Packing in Soft Formations: Low Efficiency Fluids Exacerbate Formation Damage

Frac Packing in Soft Formations: Low Efficiency Fluids Exacerbate Formation Damage

Hydraulic Fracturing Stimulation in Poorly Consolidated Sand: Mechanisms and Consequences

Optimizing Sand Control Treatments Using Gauge Data

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