Polyaspartates for Oil and Gas
One of the biggest challenges oilfield operators face is scale in oilfield equipment, which can have significant ramifications if not addressed. Polyaspartates can be used in the oil and gas sector as an effective, more sustainable scale inhibitor than many other traditionally used options on the market.
In this article, we'll review:
Summary
- Scale formation in the oil and gas sector
- Various chemical treatments of scale
- Uses of polyaspartates in the oil and gas industry for scale inhibition
scale formation in oilfield equipment
Let's start with the basics: what is scale formation in the context of oilfield equipment?
Below are some of the most common forms of scale in the oil and gas environment:
- Calcium carbonate (calcite)
- Iron and zinc sulfides
- Barium sulfateinc
Calcium carbonate is the most common form of scale formation in the oil and gas environment. As temperatures increase, the solubility of calcium carbonate decreases. Furthermore, rising pH also contributes to calcium carbonate scale deposition, as it dissolves more readily in more acidic environments.
If allowed to form, scale can lead to pressure reductions and failure of oilfield equipment, not to mention lost production. Bottom line, scale formation costs oilfield operators time, money and working hours.
So how does scale form in oilfield equipment?
In many cases scale formation is the result of three factors: 1) incompatible brine mixing 2) changes in temperature and pressure and 3) brine evaporation.1
In terms of treatment, there are also factors that can blunt the impact of scale inhibitors.
For example, one study notes the impact of enhanced oil recovery (EOR) chemicals on scale inhibition chemicals, noting the results suggested "the performance of scale inhibitors could be substantially affected by the EOR chemicals."2
what are some traditional scale inhibition treatments?
Traditionally, scale treatment in the oil and gas environment comes in two stages: prevention, in the form of scale inhibitors, and dissolution when scale has already formed and needs to be removed from the system. In this article, we will focus on scale inhibition.
Some common forms of scale inhibitors include, according to the International Chemical Group:
- Phosphonates
- Phosphate esters
- Polyacrylates
Phosphonates, for example, have been used for many years in the oil and gas sector for their scale inhibiting properties. However, challenges with aminomethylenephosphonate-based chemicals include lack of biodegradability and production system intolerance.3
"Most current SIs have a trade-off between inhibition performance and costs," Mady et al note. "However, they lack other important characteristics that must be considered before their application in the field, such as calcium tolerance and biodegradability. In addition, it is required that remarkable SIs present high thermal stability for squeeze treatment applications."
Low biodegradability is a challenge, particularly in regions with strict environmental regulations. The persistence of scale inhibitor chemistries in the oil and gas environment thus can lead to regulatory ramifications for an oil and gas operation.
polyaspartates for oil and gas
What are the benefits of polyaspartates for oil and gas scale inhibition?
As we've noted in previous articles, biopolymers like polyaspartic acid offer both performance and sustainability. To quickly recap some of the benefits of polyaspartates, both for oil and gas and other industry use cases:
- Biodegradability means the chemistry won't persist in the environment for an extended period of time
- Biocompatibility, meaning not harmful to living tissue
- Multifunctionality (i.e., potentially eliminate the need to hold multiple chemistries in inventory)
- Chelation of ions (e.g., calcium, magnesium) that can lead to scale deposition
- Effective in a wide range of industries and use cases
Polyaspartic acid, for example, is one biopolymer that can be used across a variety of industries, including agronomy, cooling towers and, per the focus of this article, the oil and gas sector.
As the green/sustainability movement continues to pick up speed around the world, industry is looking for chemicals that maintain performance levels they are accustomed to while simultaneously leveling up sustainability profile of their operation.
Polyaspartic acid offers great biodegradability, meaning it won't linger for excessive periods of time after application. This compares with relatively poor biodegradability for other treatment chemicals, like polyphosphates and polyacrylates.
However, on the other hand, one challenge polyaspartic acid alone faces is thermal stability, which obviously is a major problem in the oil and gas environment. The solubility of calcium carbonate, for example, decreases as temperature rises, meaning any scale inhibitor treatment must also be able to withstand high temperatures.
As such, there has been much research done in the area of fortifying polyaspartic acid to increase thermal stability. In other words, so it can hold up in the rugged oil and gas environment and do the job for longer before safely biodegrading. One study looked into the performance of a modified polyaspartic acid in relation to that of polyaspartic acid.4 The study found the thermal stability of the modified polyaspartic acid to be superior to the unmodified polyaspartic acid over time and temperature.
Summary
L-aspartic acid is a building block for a powerful biopolymer with seemingly endless possibilities. Furthermore, the biodegradability of L-aspartic acid-based polymers, polyaspartates, makes them a more sustainable option than some of the traditional treatment chemicals (including those noted above).
Polyaspartates, like other classes of biopolymers, will have a key role to play in the ongoing sustainability movement.
Interested in learning more about Dober's biopolymer offerings for the oil and gas sector? We'd be happy to chat about our biopolymer products and how they can help you achieve a more sustainable — yet still effective and efficient — operation.
References
1. Muhammad Shahzad Kamal, Ibnelwaleed Hussein, Mohamed Mahmoud, Abdullah S. Sultan, Mohammed A.S. Saad, Oilfield scale formation and chemical removal: A review, Journal of Petroleum Science and Engineering, Volume 171, 2018, Pages 127-139, ISSN 0920-4105,
https://doi.org/10.1016/j.petrol.2018.07.037.
(https://www.sciencedirect.com/science/article/pii/S0920410518306120)
2.Qiwei Wang, Feng Liang, Waleed Al-Nasser, Faez Al-Dawood, Tawfiq Al-Shafai, Hameed Al-Badairy, Shouwen Shen, Hassan Al-Ajwad, Laboratory study on efficiency of three calcium carbonate scale inhibitors in the presence of EOR chemicals, Petroleum, Volume 4, Issue 4, 2018, Pages 375-384, ISSN 2405-6561,
https://doi.org/10.1016/j.petlm.2018.03.003. (https://www.sciencedirect.com/science/article/pii/S240565611730144X)
3. Synthesis and Study of Modified Polyaspartic Acid Coupled Phosphonate and Sulfonate Moieties As Green Oilfield Scale Inhibitors. Mohamed F. Mady, Abdur Rehman, and Malcolm A. Kelland. Industrial & Engineering Chemistry Research 2021 60 (23), 8331-8339. DOI: 10.1021/acs.iecr.1c01473
4. Yan, Jiawei, Xiao Tan, and Suitao Qi. 2023. "High-Temperature-Resistant Scale Inhibitor Polyaspartic Acid-Prolineamide for Inhibiting CaCO3 Scale in Geothermal Water and Speculation of Scale Inhibition Mechanism" Water 15, no. 8: 1457. https://doi.org/10.3390/w15081457