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Effective Fluid Diversion during Fracture Stimulation Operations with Degradable Solids

IP.com Disclosure Number: IPCOM000242003D
Publication Date: 2015-Jun-12
Document File: 7 page(s) / 404K

Publishing Venue

The IP.com Prior Art Database

Abstract

Degradable solids find increasing use as the preferred fluid diversion materials in well completions and in re-fracture stimulation applications. Perf-and-plug well completions multi-cluster fracturing stimulations are particularly amenable to degradable solids used as temporary plugging agents. The degradable materials enter into a freshly created or a pre-existing flow pathway, create a pack in it and reduce fluid access to the primary flow paths to divert the fluid to other poorly stimulated otherwise areas of the wellbore. The efficiency of fluid diversion operations depends on the extent of fluid flow reduction achieved by the solid pack, which in turn depends on the particle packing efficiency and solid/void volume to reduce the pack permeability. Various methods have been used to minimize solid pack permeability. In one approach, fiber shaped degradable particulates are used to form a filter cake on a plug to achieve low permeability. In another approach, particulates with multimodal particle size distribution were used with the intent that smaller particles may fill the voids created by the larger particles which initiated the plug formation, thereby minimizing the void volume available to fluid flow. However, very few studies aim at experimentally investigating the underlying concepts. Additionally, the role of the geometrical shape and the dimensions of the flow path have not been addressed. The objective of this study was to understand the relationships among diverter particulate sizes and the shape of the flow pathway(s). A special apparatus with a wedge-shaped flow path to simulate a perforation/fracture was built in-house. The effect of non-fiber type particulates with different particle sizes and particle size distributions on fluid control in relation to the width of the entry and exit points of the flow pathway was studied. Fluid leakage values and pressure buildup were measured under constant flow conditions, and the sequence of events leading up to the plug formation was recorded. Results show initial bridging by large particles within the wedge-shaped pathway followed by packing of the inter-particle space by medium and smaller particles. The results can potentially allow for tailoring the particle size distribution to meet fluid loss requirements for realistic fracture or perforation dimensions.

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Effective Fluid Diversion during Fracture Stimulation Operations with Degradable Solids

Abstract

Degradable solids find increasing use as the preferred fluid diversion materials in well completions and in re-fracture stimulation applications. Perf-and-plug well completions multi- cluster fracturing stimulations are particularly amenable to degradable solids used as temporary plugging agents. The degradable materials enter into a freshly created or a pre-existing flow pathway, create a pack in it and reduce fluid access to the primary flow paths to divert the fluid to other poorly stimulated otherwise areas of the wellbore. The efficiency of fluid diversion operations depends on the extent of fluid flow reduction achieved by the solid pack, which in turn depends on the particle packing efficiency and solid/void volume to reduce the pack permeability. Various methods have been used to minimize solid pack permeability. In one approach, fiber shaped degradable particulates are used to form a filter cake on a plug to achieve low permeability. In another approach, particulates with multimodal particle size distribution were used with the intent that smaller particles may fill the voids created by the larger particles which initiated the plug formation, thereby minimizing the void volume available to fluid flow. However, very few studies aim at experimentally investigating the underlying concepts. Additionally, the role of the geometrical shape and the dimensions of the flow path have not been addressed.

The objective of this study was to understand the relationships among diverter particulate sizes and the shape of the flow pathway(s). A special apparatus with a wedge-shaped flow path to simulate a perforation/fracture was built in-house. The effect of non-fiber type particulates with different particle sizes and particle size distributions on fluid control in relation to the width of the entry and exit points of the flow pathway was studied. Fluid leakage values and pressure buildup were measured under constant flow conditions, and the sequence of events leading up to the plug formation was recorded. Results show initial bridging by large particles within the wedge-shaped pathway followed by packing of the inter-particle space by medium and smaller particles. The results can potentially allow for tailoring the particle size distribution to meet fluid loss requirements for realistic fracture or perforation dimensions.

Introduction

There is a wide range of solid flow diverter product available on the market for enhancement of oilfield operation. Some of them are targeting flow diversion at wellbore (perforation balls) and some in the far field (calcium carbonate and sodium chloride salt). In case of the near wellbore and far field division, the process of creating the differential pressure is not completely understood. For the better understanding of the flowing path shutting a slot flow testing method was invented the advantages of the...