Small, Highly Conductive Fractures Near Reservoir Fluid Contacts: Application to Prudhoe Bay

Martins, Paulo; Collins, Pat; Rylance, Martin; Ibe, O.E.; Kelly, R.T.; Bartel, Paul

doi:10.2118/24856-ms

Cited by 26 publications

(11 citation statements)

References 8 publications

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“…Recent workover experience in the ~ 100 md "Zone 3" of the main Ivishak pay formation shows propped fractures definitely stimulating production from that zone, with fracture stimulations increasing field productivity by ;::;: 20% (more than 200,000 bopd). 3,4 However, with the underlying, high permeability (> 1000 md) "Zone 4" watered out, fracture penetration for Zone-3 is severely limited in many areas of the field to avoid fracturing into a watered out Zone-4.…”

Section: Figure 2 -Typical Cook Formation Log Section In Gullfaks Fieldmentioning

confidence: 99%

“…Such a indirect vertical fracture completion (IVFC) achieves several goals: I) First, the fracture stimulates production from lower penneability pay, increasing reserve recovery from that zone of the fonnation, 2) Second, connection is established to the high penneability zone of the formation, but production from the high penneability pay, through the fracture, is restricted, thus final production is more unifonnly distributed over the fonnation thickness, optimizing reservoir management, 3) Third, if the high penneability zone is prone to sand production, then the need for sand control is bypassed, often reducing completion costs. This can be of critical importance in areas (such as the North Sea) where seawater injection leads to severe scaling problems where scaling often totally plugs gravel pack wells quickly after WET.…”

Section: Introductionmentioning

confidence: 99%

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Post-Frac Productivity Calculation for Complex Reservoir/Fracture Geometry

Bale¹,

Smith²,

Settari³

1994

Proceedings of European Petroleum Conference

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This paper presents a simple, practical approach to calculating post-frac productivity for indirect vertical fracture completion (IVFC) wells. The case envisioned is one where the main pay is not adjacent to perforations; with wellboreto-pay communication being created via a wide propped vertical fracture. Such a fracture generally involves tip screenout type treatment designs, though that is not a subject of this paper.Previous publications·· 2 presented a case history of limiting perforations in a well to competent, lower permeability rock, and creating a propped fracture to communicate wi~ weaker, higher permeability pay.An IVFC well in thlS formation served two goals: 1) to avoid need for gravel packing or other sand control measures required when the main pay is perforated, and 2) to maximize production from lower permeability pay sections, thus delaying water breakthrough (WBT) and increasing total reserve recovery. As part of that case history, a brief calculation scheme was proposed for predicting post-frac PI.This paper discusses details of this calculation procedure, which is presented in a more general (partly dimensionless) form. Examples of predicted PI using these calculations are presented for several field cases where complex fracture completions of this type are being considered and implemented.In addition, accuracy of the simple, analytical calculations are tested against 3-D reservoir modeling. Results of the numerical modeling generally verify the simple procedure, but also place some limits on where / when analytical calculations should be used. The 3-D model is then used to consider possible impacts of turbulent flow and other parameReferences at end of paper.ters not included in the analytical calculation. Turbulent flow in the fracture was found to be a significant factor, even for single phase flow of oil.Finally, predicted PI is compared to field measured postfrac results for several cases. Many field cases show unmistakable indications of turbulent flow, making it clear this facter must be considered in design of such completions.

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Section: Figure 2 -Typical Cook Formation Log Section In Gullfaks Fieldmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Post-Frac Productivity Calculation for Complex Reservoir/Fracture Geometry

Bale¹,

Smith²,

Settari³

1994

Proceedings of European Petroleum Conference

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“…11,12 Prats demonstrated that a propped fracture completion may be "viewed" as a completion with an increased effective wellbore radius (r w '). The fracture skin, Sr, is then defined as 492 Sf = -In(rw'/Lf) -In(Ltirw) ...... (2) where rw is the wellbore radius and Lris the fracture propped half-length. Values of rw'lLr are given as a function of the fracture conductivity ratio (FCD).l2 This is defined as…”

Section: Skin Analysis Of Fandp Completionsmentioning

confidence: 99%

“…If we do not desire a fracture to grow into unwanted water and/or gas zones and ifthere are no strong formation barriers to limit such a growth, the design of treatment volume and pump rate requires special attentions. 2 In this case, one may assume an uncontained (radial) fracture geometry with Lrbeing less than one half of the total desired height.…”

Section: Fracture Conductivity and Propped Length Requirementsmentioning

confidence: 99%

Design, Execution, and Evaluation of Frac and Pack (F&P) Treatments in Unconsolidated Sand Formations in the Gulf of Mexico

Wong

Fors

Casassa

et al. 1993

SPE Annual Technical Conference and Exhibition

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ABSTRACT· This paper presents a skin analysis of Frac and Pack (F&P) completions and summarizes our F&P design methodology, field execution procedures, and productivity responses for ten F &P jobs done in a wide range of field conditions in the Gulf of Mexico (GOM). The purpose of the paper is to identify design and job execution requirements to better optimize F&P treatments.The skin analysis revealed that near-wellbore skins, from perforation tunnels (casing and cement sheath) and a choked fracture, can dominate the final F&P completion skin. Nearwellbore skins are particularly damaging when F&P treatments have low dimensionless fracture conductivity ratios (FeD) and when perforation tunnels are not filled with permeable proppant. Therefore, F&P designs should aim for high fracture conductivities with FeD greater than one and fill perforation tunnels with proppant permeability greater than 200 times the formation permeability. For most applications in GOM, such requirements require larger proppant sizes that may not satisfy gravel packing requirements.Besides maximizing the FeD, the perforating completion and the execution of F&P should include steps to minimize nearwellbore damage. These include perforating with high shot density and big hole charges, initiating or breaking down the fracture with high pump rate, packing the fracture (near the wellbore) with high concentration loading of sand, implementing fluid quality control, and providing sufficient breakers for the fracturing fluid.

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“…Once the fracture geometry and C L have been determined, further analytical techniques 3,4 are available for designing the correct TSO fracture stimulation. These analytical tools are of great benefit to the user when anticipated fracture dimensions are well understood [4][5][6] . In many instances, however, it is difficult to predict a fracture's geometry.…”

Section: Introductionmentioning

confidence: 99%

Flexible, Real-Time Tip-Screenout Fracturing Techniques as Applied in California and Alaska

Upchurch¹

1999

SPE Western Regional Meeting

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis paper discusses the application of two variations on a flexible tip screenout (TSO) technique that allows for realtime changes of fracture treatments to compensate for uncertainty in fluid leakoff and fracture geometry. The basic premise for each technique is the same; that is, change frac job size as necessary during the job to attain a TSO using realtime data. The techniques differ, however, because of physical system constraints, which result in different types of data being available to make real-time decisions. In the West Sak Field of Alaska, real-time bottom-hole pressure is available for decision making purposes (a best-case scenario). In the East Wilmington Field of California, real-time bottomhole pressure is not available; thus, the flexible TSO technique is implemented differently to yield the best possible flexibility under these less-than-optimal data conditions.

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Small, Highly Conductive Fractures Near Reservoir Fluid Contacts: Application to Prudhoe Bay

Cited by 26 publications

References 8 publications

Post-Frac Productivity Calculation for Complex Reservoir/Fracture Geometry

Post-Frac Productivity Calculation for Complex Reservoir/Fracture Geometry

Design, Execution, and Evaluation of Frac and Pack (F&P) Treatments in Unconsolidated Sand Formations in the Gulf of Mexico

Flexible, Real-Time Tip-Screenout Fracturing Techniques as Applied in California and Alaska

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