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

Abstract

Unconsolidated formations and high permeability reservoirs are susceptible to fines migration.  The main contributing factors are high formation fluid velocity, wettability alteration, change in water salinity, and rock failure.  Typically, fines migration problem occur in the near-wellbore vicinity due to high drawdown pressures.  Depending on the severity, it can result in rapid productivity decline, erosion damage to downhole and/or surface hardware, and surface facility upsets. 

A properly designed frac pack frac pack can mitigate the migration of fines if it is indeed a problem.  However, as insurance there are some technologies currently used to address fines migration in frac packs.  These technologies have some limitation such as only being designed to treat the fracture but not the near-wellbore vicinity, prone to causing long-term damage to proppant pack conductivity, and needing remedial work to cleanup the proppant pack followed by retreatment.

In this paper, we will discuss the development of a new technique that effectively controls the migration of fines both within the formation surrounding the near wellbore as well as fracture area, and which does not affect proppant pack conductivity.  We first detail the laboratory testing program followed to develop this technology including synthetic pack fines migration core flow evaluation, compatibility with frac-pack fluids, proppant pack and formation damage.  Thereafter, we discuss the field deployment process and compliment with case histories.  The laboratory results demonstrate that fines migration in the synthetic pack is drastically reduced with this new technique, that the technique is applicable up to 280°F, and that it can be deployed in commonly used frac-pack fluids.  Production results of treated frac-pack wells have met expectation and after a year no fines production has been reported.

Introduction

In cased hole wells requiring sand control, frac pack is a very popular sand control completion technique as detailed by Norman (2004) and Ayoub et al. (2000). Frac-pack design involves creating short, wide, and highly conductive fractures to bypass near-wellbore damage followed by completely packing the annulus between the casing and screen.  The proppant in the fracture and annulus is sized to prevent sand production and the screen is sized to prevent proppant flowback.  The other cased hole sand control technique is a gravel pack either a high-rate water pack or gelled gravel pack.