Overbalanced Perforating Yields Negative Skins in Layered Reservoir

Pizzolante, Ítalo; Grinham, Stephen; Xiang, Tian; Jihong, Lian; Khong, Chee Kin; Behrmann, L.A.; Mason, Steve

doi:10.2523/104099-ms

Cited by 3 publications

(1 citation statement)

References 17 publications

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“…The first is that, during this time frame, research was focused on perforation damage removal, rather than on depth of penetration. This was for good reason, as clean tunnels are an essential component of a lowskin perforated completion, and maximizing well deliverability is the ultimate goal [18][19][20]. A second reason is that facilities were not large enough to economically test the deepest penetrating charges under stress.…”

Section: Evolution Toward the Presentmentioning

confidence: 99%

A Survey of Industry Models for Perforator Performance: Suggestions for Improvements

Behrmann

Grove

Walton

et al. 2009

SPE Annual Technical Conference and Exhibition

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For perforated natural completions, well productivity is dependent on the depth of the perforation tunnels extending beyond the drilling damage (all other things being equal). It is therefore important to accurately predict perforation depth at downhole conditions, in order to enable accurate prediction of well performance.Most industry penetration models in use today are based largely on laboratory experiments conducted during the 1960's through the 1990's. Over the past decade or so, it has been observed that the accuracy of these models has not kept up with the true downhole performance of modern shaped charge perforators. Furthermore, different models can give quite different predictions of penetration performance of the same perforating system, in the same downhole environment.To address this situation, the authors have recently conducted an extensive series of laboratory experiments, the results of which are enabling improved prediction of penetration performance in the field. Several hundred modern charges of different sizes have been shot into multiple rock types under simulated downhole stress conditions.The primary conclusions of this work include: (1) historical penetration models tend to overpredict penetration at downhole conditions; (2) some industry models overpredict to a greater extent than others; (3) the discrepancy is partly due to the industry's continued reliance on performance into surface concrete targets. In addition, we observe that historical models tend to treat all charges equally, imposing the assumption that increased performance in one target (i.e. surface concrete) always and everywhere ensures increased performance in all targets (i.e. various stressed rocks). While this intuitive assumption is proven true as the "rule" on average, we find some significant exceptions. Although these exceptions complicate predictive modeling efforts, they do suggest opportunities to optimize charges for certain targets preferentially over others.Our conclusions have led to ongoing work including (1) the development of improved penetration models, which rely exclusively on stressed rock, rather than unstressed concrete, performance; (2) the development of perforators optimized for downhole conditions, rather than for surface concrete.

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Section: Evolution Toward the Presentmentioning

confidence: 99%

A Survey of Industry Models for Perforator Performance: Suggestions for Improvements

Behrmann

Grove

Walton

et al. 2009

SPE Annual Technical Conference and Exhibition

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Solids-Free Viscoelastic Fluid Loss Pills and Dynamic Underbalance Improve Productivity from Newly Perforated Wells

Arangath

Babalatirov

Griffith

et al. 2010

SPE Annual Technical Conference and Exhibition

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Many operators in Kazakhstan are producing from carbonate reservoirs with fairly low permeability and porosity with the presence of dominant natural fractures. The completion and perforation of the reservoir are critical phases during which special attention must be placed on the well cleanup to obtain the maximum hydrocarbon productivity. Wells in the tight carbonate formation of certain fields in western Kazakhstan have historically been perforated in overbalance conditions or in static underbalance conditions that require killing the well immediately after the perforation for installing the permanent completion. After the permanent completion has been put in place, an acid wash must be performed to remove all the damage induced by the killing operation and the perforating debris. Both ways of perforating the wells expose the reservoir to potentially damaging fluids during and after the perforation. The exposure time of these fluids can be prolonged if adverse meteorological conditions are encountered. The damaging fluids can significantly impair the productivity by blocking the newly perforated tunnel, as well as by filtering through the natural fractures, which in turn makes it very difficult to remove even after as acid wash. As a result, the wells do not produce to their full potential. A new perforating approach utilizing a dynamic underbalanced technique, in conjunction with a solids-free, viscoelastic-based, fluid loss pill, was introduced in several new wells in western Kazakhstan for a major operator. The fluid loss pill was designed to be solids-free and to be easily broken, leaving no residue downhole. There were four main requirements for the fluid pill: Effective—capable of stopping or minimizing completion brine losses at bottomhole static temperatures (BHSTs) up to 137°C. Degradable—easy to clean and with minimal residual damage to the reservoir or the perforations. Compatible—fully compatible with reservoir fluids and any well service fluids. Solids-free—making the post-completion cleanup operation easy. The carbonate reservoir where this new approach was utilized has permeabilities varying from 6 to 38 mD, while the present reservoir pressure is approximately 4,200 psi at the reference depth of 3550 m. The new perforation approach allowed obtaining a cleaner perforation tunnel, increasing the average production compared with wells draining from the same reservoir that were completed with the traditional technique. The average production obtained with the new approach is approximately double that of the conventional technique. This has been verified on a campaign carried out on 11 wells, all located in the same area of the field, four of which were completed with the new perforation approach. Several other treatments have been performed and have indicated similar trends in production.

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Perforating System Performance at Downhole Conditions: Recent Advances in Modeling and Prediction

Grove

Harvey

Martin

2016

SPE International Conference and Exhibition on Formation Damage Control

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Modeling of perforating system performance at downhole conditions has received significant attention in recent years. This is due to increased recognition of the importance that perforating plays in well performance, and ultimately asset value. To this end, models have been recently developed to more reliably predict key downhole parameters, including formation penetration depth, perforation cleanup, and skin. These new models have been incorporated into a software tool, which enables users to optimize perforating designs around completion and production objectives, while considering operational constraints. This paper summarizes these recent advances, some previously unpublished, and briefly summarizes recent case studies highlighting the impact of the improved modeling capabilities.

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Overbalanced Perforating Yields Negative Skins in Layered Reservoir

Cited by 3 publications

References 17 publications

A Survey of Industry Models for Perforator Performance: Suggestions for Improvements

A Survey of Industry Models for Perforator Performance: Suggestions for Improvements

Solids-Free Viscoelastic Fluid Loss Pills and Dynamic Underbalance Improve Productivity from Newly Perforated Wells

Perforating System Performance at Downhole Conditions: Recent Advances in Modeling and Prediction

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