Unique Paraffin Inhibition Technique Reduces Well Maintenance
Authors: Charles J.G. , Marcinew R.P. 
Published: March 2010

Removal and inhibition of paraffins from downhole tubulars can be handled by many different means. Mechanical, thermal, chemical or a combination of these systems will usually lead to a regularly scheduled sequence of events for well maintenance. The frequency of the treatments is based on the effectiveness of the system chosen.

A unique process has been developed which may be used in performing a number of useful junctions in the prevention of paraffin fouling. This process has the ability to generate heal for melting and simultaneously converting the residuals to a water-dispersible material. The resultant effect on the cleaned tubing and rods is the creation of a highly water-wet surface. This surface acts to retard paraffin deposition with a water layer between the wax and metal. The adhesiveness or the paraffin is greatly reduced. Crystals that do form are easily washed away with fluid production. This technique is widely applicable and can provide long-term relief from the difficulties associated with producing problematic crude oils.

Introduction

Deposition of heavy hydrocarbons, such as paraffins, asphaltenes and resins on production tubulars and equipment has long been a problem in many oil-producing areas(1). Numerous methods have been used to remove these deposits on varying maintenance schedules(2). Further, various chemicals and systems have been used to inhibit such deposits with limited success.

There are few, if any, treatments that attempt to both remove existing deposits and inhibit future deposits. The majority of the methods is aimed at reopening flow channels to restore production to previous levels. Hot oiling, cutting, pigging and solvents are the primary means by which paraffin is removed or displaced. Inhibition is commonly attempted with crystal modifiers or surfactants. These can be continually fed down the annulus, batch-treated or displaced into the reservoir for slow release with produced fluids.

Crystal modifiers act in blocking the formation of paraffin Crystals. Growth sites are blocked by the addition of chemicals on a regular basis. Their effectiveness is dependent upon proper placement and concentration.

Surfactants act primarily as wettability enhancers in an attempt to reduce the adhesiveness of the paraffin particles. They can either act to reduce the paraffin's ability to adhere to itself, or its ability to adhere to the surface of the tubing. They also are dependent upon application effectiveness and downhole conditions. Cleanliness of the surface to be treated is a primary factor in the surface-coating type inhibitor. Without a sandblasted clean surface on which to coat, their effectiveness and longevity are severely reduced(3).

Smooth coatings, such as plastics, have been utilized in reducing paraffin deposition(4). These have met with limited success. They can be easily abraded and are difficult to work with. The worn surface becomes as rough or rougher than the original steel surface. Although smooth surfaces have been shown to be effective for deposition inhibition, they arc difficult to maintain in an oil well.

The limits of these conventional inhibition methods arc evident and no single mechanism has had widespread application.