Improved Understanding of Proppant Transport Yields New Insight to the Design and Placement of Fracturing Treatments

Brannon, Harold; Wood, W.D.; Wheeler, Richard S.

doi:10.2118/102758-ms

Cited by 9 publications

(1 citation statement)

References 7 publications

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“…Shah et al built a high-pressure parallel plate flow cell with an integrated fiber optic vision system and LED for simulating downhole fractures (Shah et al, 2001). Many researchers have studied the plate model, however, the current research on this model mainly focuses on small-scale and simple single fractures (Brannon et al, 2006;Shokir and Al-Quraishi, 2007;Woodworth and Miskimins, 2007;Dayan et al, 2009;Zhai, 2012). In addition, Li developed a large-scale visualization proppant placement device in 2016 for complex fracture networks considering perforation parameters based on geometric similarity and Reynolds number similarity criteria, which can change the number and angle of fractures (Li, 2016).…”

Section: Introductionmentioning

confidence: 99%

Research on the transport behavior of microparticle proppants inside natural fractures

Liu,

Wang,

et al. 2024

Front. Earth Sci.

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As a crucial exploration technique for unconventional reservoirs, hydraulic fracturing enables the formation of complex fracture networks, thereby facilitating the flow of oil and gas. The closure of natural fractures decreases stimulation performance. Microparticle proppants are used to fill natural fractures and effectively increase the stimulation area. The 100-mesh proppant conventionally used in field operations may be insufficiently small to effectively access natural fractures. In order to effectively overcome natural fractures closure, microparticle proppants (i.e., proppants with a diameter of 75 μm (200-mesh) or less) are required. The particle size threshold test of microparticle proppants placement is conducted to determine the size threshold of proppants flowing into natural fractures. The microparticle proppants placement experiment in multi-branch fractures is conducted to investigate the volume difference of proppants in different fractures. Numerical simulations are performed to model proppant transport within fractures of actual dimensions to facilitating the optimization of stimulation parameters. The main conclusions are as follows: (1) Effective inflow of microparticle proppants requires a size threshold of proppants. For the 200-mesh proppants, the size should be less than half of natural fractures width when microparticle proppants effectively flow into natural fractures. (2) Sand concentration affects the size threshold of microparticle proppants. The size threshold should appropriately increase to ensure the inflow of proppant. (3) Difference of multi-branch fracture width has a significant effect on volume of microparticle proppants inside fractures. When the width ratio of multi-branch fractures exceeds 2, this effect becomes obvious. (4) Particle size has an effect on proppant placement. 200-mesh proppants can obtain uniform distribution of proppants among natural fractures. 140-mesh proppants can obtain maximum proppant volume among natural fractures. Sand concentration significantly affects proppant placement performance. The optimal sand concentration is 60kg/m3. The pumping rate for a single cluster fracture should not be excessively low. The pumping rate should be larger than 0.5m3/min and the optimal pumping rate 2m3/min. In this paper, the particle size and concentration of particulate proppant are optimized and the geometric characteristics of fractures are considered. These conclusions provide important practical guidance and scientific basis for the optimization and application of hydraulic fracturing technology.

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Section: Introductionmentioning

confidence: 99%

Research on the transport behavior of microparticle proppants inside natural fractures

Liu,

Wang,

et al. 2024

Front. Earth Sci.

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A New Correlation for Relating the Physical Properties of Fracturing Slurries to the Minimum Flow Velocity Required for Transport

Wood¹,

Wheeler²

2007

All Days

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Optimization of effective fracture area is among the principal tenets of fracturing design engineering. It is well understood that effective fracture area is a first order driver for well productivity, and that optimization of effective fracture area is often critical to economic exploitation of reservoir assets. Extensive testing in a large-scale slot apparatus was conducted to evaluate the relative effects of various component and treatment parameters on the proppant transport capability of various slurry compositions. The acquired data were utilized to determine the minimum horizontal slurry velocities necessary for proppant transport using the respective slurry compositions. An ‘index’ to define the physical properties of a given proppant and fluid composition was defined. An empirical model was then derived to determine the minimum horizontal flow velocity required for suspension transport of a given slurry composition based upon its Slurry Properties Index. The minimum suspension transport velocity may then be compared to the flow velocity profiles from fracture design programs to estimate the propped fracture length likely be observed for those conditions. Utilizing the new model, the most favorable combination of fracturing slurry component properties and pumping parameters can identified and incorporated in fracturing treatment design and applications to optimize effective propped fracture length, and thereby well performance. Introduction and Background Poor proppant transport can result in excessive proppant settling, often into the lower regions of the created fracture below the productive interval, yielding relatively short effective fracture lengths and insufficient coverage of the total height of the productive zone. Additionally, inadequate clean-up of the resultant propped fracture result in significant reduction of the conductivity of the propped fracture area. The cumulative effects of the afore-mentioned phenomena can result in a reduction of overall stimulation efficiency, yielding steeper post-stimulation production declines than may be desired. Post-frac production analyses frequently illustrate that the effective fracture area is less than that expected based upon the design, suggesting the proppant was not placed effectively throughout the designed fracture area or, existence of excessive proppant-pack damage. Optimization of effective fracture area is often critical to economic exploitation of reservoir assets, thus maximization of the propped fracture area is a key parameter for generating desired stimulated well performance. Efforts to improve effective fracture area have historically focused on the proppant transport capability of the fracturing fluid and the fracture clean-up attributes. A better understanding of the proppant transport process and the controlling variables was thought to have the potential for developing improved methodologies to maximize the effective fracture area. The relative effects on proppant transport of the various proppant slurry component and treatment parameters were evaluated via extensive testing at the University of Oklahoma's Well Construction Technology Center. The techniques developed by Biot and Medlin to determine terminal settling velocities and suspension regimes were used to process and analyze the acquired data1.

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Minimizing Over-Flush Volumes at the End of Fracture-Stimulation Stages - An Eagle Ford Case Study

Al-Tailji

Northington²,

Conway³

et al. 2014

All Days

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With the growing popularity of multi-stage hydraulic fracturing treatments in horizontal wellbores, various completion systems have been utilized for mechanical isolation and staging of individual fracture treatments. One of the more popular fracture staging techniques is the plug-and-perf technique in cemented casing, which requires the lateral section of the wellbore to be free of debris and proppant so that the plug and perforation tool string can be pumped down to the desired setting depth. Proppant that has settled in the lateral can result in plugs getting stuck and prematurely setting at the wrong depth, requiring costly intervention work and delaying the progress of completing the well. The industry standard practice to prepare a clean wellbore has been to over-flush each fracture treatment by 50 to 100 barrels in excess of the volume to the perforations. This practice has raised concerns about disturbing near-wellbore proppant conductivity and potentially harming fracture continuity with the wellbore, and thus productivity. Since operators have achieved satisfactory economics in many shale plays, this practice continues despite its controversy. These concerns have led to experiments in minimizing excess flush volumes in wells located in the liquids-bearing window of the Eagle Ford Shale. This paper proposes a process involving the use of real-time treatment data displayed within a wellbore model simulation to adjust the flush volume of each stage based on the reduction in proppant concentration at the perforations. Over 200 stages were successfully placed with this method with no incidences of plugs sticking in the lateral. This paper contains a selection of treatment charts and wellbore diagrams from actual applications of this method. Simulated fracture profiles of different over-flush scenarios are also compared and discussed. This paper will be useful for engineers and managers involved in well completions and stimulation, and presents detailed methodology for successfully applying this strategy in their fields. By applying these procedures, continuity between the proppant pack in the fractures and the wellbore should be improved, and fresh water usage will be reduced.

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Improved Understanding of Proppant Transport Yields New Insight to the Design and Placement of Fracturing Treatments

Cited by 9 publications

References 7 publications

Research on the transport behavior of microparticle proppants inside natural fractures

Research on the transport behavior of microparticle proppants inside natural fractures

A New Correlation for Relating the Physical Properties of Fracturing Slurries to the Minimum Flow Velocity Required for Transport

Minimizing Over-Flush Volumes at the End of Fracture-Stimulation Stages - An Eagle Ford Case Study

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