Development of a New Polymer Inhibitor Chemistry for Downhole Squeeze Applications

Abstract

Summary Scale inhibitor squeeze treatments have regularly been conducted to prevent both sulphate and carbonate scale depositions in a specific North Sea field for more than 10 years. However, some wells, in which the fluid is producing from the "clean" sandstone formation, have experienced relatively short squeeze lives, when squeezing a conventional phosphonate scale inhibitor treatment. A research program has been conducted to develop a novel polymer scale inhibitor chemistry, which combines performance in a number of laboratory static and dynamic tests, with improved scale inhibitor adsorption properties on "clean" sandstone formations. Field trials have also been conducted with satisfactory results. This paper outlines the concept of how novel scale inhibitor chemistry was developed by incorporating a special monomer to make the final copolymer scale inhibitor. The monomer was introduced to enhance the inhibitor adsorption properties, because it carries a special functional group to improve the scale inhibitor affinity for the reservoir rock. This special functional group plays a key role for the newly developed scale inhibitor, to give improved and acceptable squeeze lives. A critical aspect of the program included optimizing the monomer content to achieve a good adsorption/desorption balance, to ensure that the scale inhibitor would be desorbed/released from the reservoir rock to meet the requirements of an acceptable squeeze program. An added bonus was that the environmental properties of the scale inhibitor polymer were also improved because of the introduction of the special monomer. A number of beaker and dynamic loop tests were conducted and the inhibitor showed an excellent efficiency in both sulphate and carbonate scale inhibition performance tests under the test conditions adopted. This paper also presents detailed laboratory and field data; the treatment design strategy and deployment method adopted for the scale inhibitor.

Selection of Scale Control Strategy on a Sub Sea Developed Field in the North Sea and How 6 Different Companies Contributed

“…16 Evaluation of polymers for scale squeeze application in Norway have been well published over the past few years. [17][18][19][20] For the scale inhibitor performance tests the Blane formation water chemistry outlined in Table 2 was used to represent a typical scaling regime when mixed with host platform produced water and additional seawater. The test work undertaken is outlined below:…”

Meeting the Challenges in Downhole Scale Control for High-Water-Production Horizontal Wells in an Environmentally Sensitive Part of the Norwegian North Sea

“…1 it can be seen that while the conventional carboxylic function group is included in the structure, an important feature of the chemistry is that a quaternary amine monomer is also introduced into the structure. Similar scale-inhibitor chemistry has been applied in one of the North Sea fields (Montgomerie et al 2009). It is believed that the introduction of the positive-charged monomer offers the desirable level of adsorption onto the surface of sandstone formations necessary for use as a scale inhibitor by a squeeze treatment.…”

“…It is believed that the introduction of the positive-charged monomer offers the desirable level of adsorption onto the surface of sandstone formations necessary for use as a scale inhibitor by a squeeze treatment. It is thought that by fixing the polymers to the surface of the formation (e.g., by electrostatic attraction), the adsorption can be enhanced (Montgomerie et al 2009). Enhanced adsorption will give a more favorable inhibitor desorption with decreased early inhibitor returns and potential to protect a larger volume of produced water.…”

Meeting the Challenges in the Downhole Scale Control for High-Water-Production Horizontal Wells in Environmentally Sensitive Part of the Norwegian North Sea

“…A similar scale inhibitor chemistry has been applied in one of the North Sea fields (SPE113926). 7 It is believed that the introduction of the positive charged monomer offers the desirable level of adsorption onto the surface of the negatively charged sandstone formations, necessary for use as a scale inhibitor by a "squeeze" treatment. It is thought by "fixing" the polymers to the surface of the formation (e.g.…”

“…by electrostatic attraction), that the inhibitor adsorption can be enhanced. 7 In addition to showing good performance data through the conventional scale laboratory screening tests, the novel inhibitor chemistry displays good environmental properties. The environmental data of the scale inhibitor are listed in Table 2.…”