Utilizing Organosilane With Hydraulic Fracturing Treatments To Minimize Fines Migration Into the Proppant Pack — A Field Application

Abstract

In many of California's shallow, low permeability formations hydraulic fracturing is necessary to enhance production rates. The low closure-stresses of some of these formations require effective proppant flowback control. Such control is not only necessary to minimize problems associated with sand production but also to preserve the integrity of the propped fracture and maintain propped fracture conductivity. Various additives and techniques have been successfully applied to control proppant flow back. These include resins, resin-coated sands, fibers, plastics, and deformable proppants. Another well production problem associated with proppant pack conductivity loss, rarely addressed by the industry, is the migration of fines from the rock matrix into the proppant pack. Fines migration reduces the permeability of the proppant pack, causing a loss of conductivity. This loss of conductivity produces a choke effect and increases the rate of a well's production decline. In California's C/D sands, in the Lost Hills field, produced fines range in size from 0.06 mm up to 0.1 mm. These fines are larger than silts and clays but smaller than fine sands. Fines production, like those generated from the C/D sands, is a natural process caused by the movement of hydrocarbons and formation water into the wellbore. An organosilane (referred to herein as "Organosilane") has been successfully applied in acidizing treatments to stabilize fines due to acid dissolution. A process was created in which Organosilane was utilized to also minimize fines migration with fractured wells. Organosilane was added at low concentrations into the pre-pad brine water injection prior to the main fracturing treatment. Based on this experience, well production results indicate the concept of adding organosilane, in conjunction with fracturing, maintained production and minimized well-pulling frequency due to fines intrusion. This paper reviews concepts and examples of treatment applications and their results. Introduction Wells are hydraulically fractured to enhance the flow potential and to accelerate reserve production. A propped hydraulic fracture is a conductive flow path super-imposed into the rock formation. This highly conductive path acts as a conduit of reservoir fluid flow from the rock matrix into the wellbore, which is equivalent to an enlarged wellbore. For an infinite conductivity fracture, the new effective wellbore radius is one half the effective fracture half-length. Fracture conductivity is defined as the product of fracture width and the propped fracture permeability. Fracture width is determined by a number of variables such as rock mechanical properties, proppant concentration, proppant amount per fracture area, and proppant size. Fracture permeability is a dynamic variable related to flow of reservoir fluids through the proppant pack. In either case, fracture conductivity is optimized with the reservoir's ability to deliver fluids to the fracture along a certain propped fracture length. This balance is known as as the dimensionless fracture conductivity.

A New Technique to Control Fines Migration in Poorly Consolidated Sandstones - Laboratory Development and Case Histories

“…Kalfayan and Watkins (1990), Stanley et al (1995) andEl Shaari et al (2008) have used organosilanes, Nguyen et al (1998) have used a surface modification agent for coating the proppant, while Kakadjian et al (2007) have exploited zeta potential altering systems, and Huang et al (2008) have used nanoparticles for treating proppants. A new technique that effectively controls the migration of formation fines both near the wellbore and around the fracture is introduced in this paper.…”