Particulate-Based Loss-Prevention Material - The Secrets of Fracture Sealing Revealed!

Kageson-Loe, Nils M.; Sanders, Mark; Growcock, Fred; Taugbøl, Knut; Horsrud, Per; Singelstad, Arne V.; Omland, Tor Henry

doi:10.2118/112595-ms

Cited by 15 publications

(8 citation statements)

References 11 publications

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“…2. The appearance of the seals confirms a well-known hypothesis on fracture sealing (e.g., Dudley et al, 2000, Kageson-Loe et al, 2008. According to this hypothesis, two simultaneous mechanisms occur while sealing an induced fracture: (a) fracture bridging happens by deposition of coarser particles along the fracture width and in relatively close proximity of the fracture-tip, (b) pressure isolation of the fracture-tip happens by accumulation of finer particles behind the formed bridge/seal.…”

Section: Permeable Rocks: Optimum Wbs Lcm Blendsupporting

confidence: 84%

“…Several papers have been published on the findings of this Joint Industry Project (JIP) since its start in the mid-2000's (see e.g., Guo et al (2009 and, Kageson-Loe et al (2008), and Sanders et al (2008)). Several experimental set-ups have been used in the experimental investigations, including a fracture sealing tester and block testing equipment.…”

Section: Other Relevant Experimental Studiesmentioning

confidence: 99%

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How to Effectively Strengthen Wellbores in Narrow Drilling Margin Wells: An Experimental Investigation

Razavi

Vajargah

Oort

et al. 2015

Day 3 Wed, September 30, 2015

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Wellbore strengthening (WBS) offers enabling technology for wells that are drilled in geological environments with a narrow drilling margin. Through its deployment, costly lost circulation events may be avoided, casing setting depths may be extended, and, in optimum cases, deeper targets may be reached with a reduced or slimmed-down casing program.The elevation of the fracture gradient offered by WBS is a complex issue that involves the growth of fractures in permeable or impermeable rocks using non-Newtonian drilling fluids that are laden with solids of varying types and sizes. Several plausible (and sometimes contradictory) models have been proposed historically to explain the WBS phenomenon, and the only way to assess the correct explanation is through dedicated experimentation. In this paper, an experimental technique to study WBS under realistic conditions is introduced, and the results of a series of larger-scale fracturing experiments using this technique are presented.The experimental set-up described here consists of a dual flow-loop/ pressure-intensifying system to carry out high-pressure borehole fracturing tests on cylindrical rock samples while maintaining continuous circulation of the drilling fluid within the borehole. The system offers full control over pore pressure, radial confining pressure and, if desired, independent axial pressure. Several injection cycles are performed to characterize the values of the fracture initiation pressure (FIP) and fracture propagation pressure (FPP) and thereby characterize WBS effects. Typical experimental variables included: the type of base fluid (water-based, oil-or synthetic-based), the concentration, type, and particle size distribution (PSD) of lost circulation materials (LCMs) used to achieve WBS effects, and the type of rock tested (sandstone and shale, i.e. permeable and impermeable rock media). Additionally, post-fracturing techniques such as thin-section analysis were employed to study the fracture geometry and deposition structure of plugging solids on the fracture surfaces.The experiments clearly show that for any rock with a given set of rock strength and failure parameters, there is an optimum PSD for maximizing WBS effects. Optimum PSD appears to be of primary importance, almost irrespective of LCM type. The results furthermore show that although a minimum concentration of LCM bridging agents is required for effective WBS, FPP does not increase significantly for concentrations above a certain upper threshold value. Moreover, increasing the injection volume during WBS squeeze treatments above a threshold value may actually lead to lower FPP values. All of these findings have important implications for field application of WBS treatments. In addition, petrographic imaging of the fracture after testing show that fracture plugging occurs in the proximity of the fracture tip and not close to wellbore face, in direct support of the Fracture Propagation Resistance (FPR) model of WBS, and in disagreement with Wellbore Stress Augmentation/ Stress Cage mode...

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Section: Permeable Rocks: Optimum Wbs Lcm Blendsupporting

confidence: 84%

Section: Other Relevant Experimental Studiesmentioning

confidence: 99%

How to Effectively Strengthen Wellbores in Narrow Drilling Margin Wells: An Experimental Investigation

Razavi

Vajargah

Oort

et al. 2015

Day 3 Wed, September 30, 2015

View full text Add to dashboard Cite

show abstract

“…This generates a packing solution in which the D 90 of the particle blend matches the maximum opening size of pores or fractures, while the D 50 (median size) of the particles is matched to the average fracture width. Years of joint-industry experimental work on fracture sealing suggests that larger particles will provide a more efficient sealing mechanism (Kaageson-Loe et al 2008). A packing algorithm based on this experimental work is also included in the software.…”

Section: Wsm Blend Design Softwarementioning

confidence: 99%

Wellbore Strengthening – Where Field Application Meets Theory

Barrett¹,

Manescu

Cueva

et al. 2010

All Days

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In recent years there has been a growing awareness of the importance of Wellbore Strengthening Material (WSM) for sealing drilling-induced and natural fractures both in permeable and impermeable zones. This paper details the application of a software tool designed specifically for determining the optimum blend of WSM to drill the formations of the challenging Cashiriari field in Peru.Several theories have been proposed to explain techniques which are in vogue for mechanically strengthening wellbores so as to control fracture propagation: Hoop Stress Enhancement ("Stress Cage") theory involves increasing the near-wellbore stress, which is usually carried out by opening fractures to tighten the wellbore and sealing the fractures immediately in that open state; "Fracture Closure Stress" theory utilizes high-fluid-loss materials to plug and tighten existing fractures; and "Fracture Propagation Resistance" theory involves isolation of the fracture tip. The design and successful utilization of a blend of WSM based on the opening and sealing of fractures suggests that these three theories are, in many respects, complementary.Any theory explaining a particular problem is ultimately judged by its practical application. Cashiriari field, known for expected mud losses to both natural and drilling-induced fractures in primarily permeable formations, is where this wellbore strengthening application took place. The optimum blend of particulates, designed using wellbore-strengthening (WBS) software, was applied consistently on the wells drilled by the operator in the Cashiriari field in the 2009-2010 campaign. Fracture resistance was increased up to 0.8 lb/gal above the minimum horizontal stress for drilling and up to 1.68 lb/gal for running casing and cementing operations. Specialized logs showing the presence of WSM inside fractures were an important tool for optimization of the WSM blend.WSM design software takes in account a multitude of drilling parameters and rock properties to predict the fracture width and estimate the required size distribution and concentration of the WSM particulates. Consequently, the WBS solution reduced lost circulation as a primary contributor of costly and time-consuming lost circulation incidents in the Cashiriari field. Further, it is anticipated that as the WBS approach is applied more widely, the incidence of lost circulation events will be greatly reduced.

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“…Other testing equipment has been developed to evaluate the sealing efficiency of LCM treatments in sealing permeable/impermeable fractured formations (Hettema et al 2007;Sanders et al 2008;Van Oort et al 2009;Kaageson-Loe et al 2008). Both particle size distribution (PSD) and total LCM concentration were found to have a significant effect on the sealing efficiency.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of fracture width limitations of granular lost circulation treatments

Alsaba

Nygaard

Saasen

et al. 2016

J Petrol Explor Prod Technol

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Drilling fluid losses into fractured shales is a major challenge. Lost circulation treatments are widely applied to mitigate the losses; however, the effectiveness of these treatments is affected by different physical properties of the used lost circulation materials (LCM). This paper presents an experimental investigation to study the effect of LCM type, concentration, particle size distribution, temperature, and LCM shape on the formed seal integrity, with respect to differential pressure, at different fracture widths. The overall objective of this study is to address the effectiveness of LCM treatments in sealing fractured shales, with specific application to the over consolidated Barents Sea overburden. Three commonly used LCMs that vary in size were used to formulate and evaluate the effectiveness of nine LCM blends. Nutshell blends effectively sealed different fracture widths with high seal integrities. Examination of the formed seal under an optical microscope and a scanning electron microscope revealed that this performance is due to the irregular shapes of these materials as well as their ability to deform under elevated pressure. Based on the results, it has been found that to effectively seal fractures using granular LCM treatments, the D90 value should be equal or slightly larger than the anticipated fracture width. However, due to both the increased risk of plugging downhole tools and the availability of larger LCM, granular LCM treatments can only be used to seal fractures up to 2000 microns. With the current limitations, other unconventional treatments are required to seal fractures wider than 2000 microns.

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Particulate-Based Loss-Prevention Material - The Secrets of Fracture Sealing Revealed!

Cited by 15 publications

References 11 publications

How to Effectively Strengthen Wellbores in Narrow Drilling Margin Wells: An Experimental Investigation

How to Effectively Strengthen Wellbores in Narrow Drilling Margin Wells: An Experimental Investigation

Wellbore Strengthening – Where Field Application Meets Theory

Experimental investigation of fracture width limitations of granular lost circulation treatments

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