Oil Well Treatments: 6 Common Issues They Address and How to Improve Their Effectiveness

Workover rig working on a previously drilled well

Oil and gas wells require ongoing maintenance to ensure optimal production. Over time, various factors can affect the performance of a well. Those factors can lead to reduced efficiency and, in some cases, a complete halt in production. To maintain the well’s health and extend its productive life, oil well treatments are often necessary. In this post, we’ll explore some of the likely reasons why an oil or gas well might need treatment, along with the most common types of treatments used to address these issues.

1. Scale Formation

One of the most common issues in wells is the formation of scale. This happens when minerals precipitate out of the produced fluids due to changes in temperature or pressure. The minerals can accumulate inside the wellbore, equipment, or pipelines, restricting flow and reducing the efficiency of oil recovery.

Scale formation in oil well casing (source: Merus Oil and Gas).

Treatment: To prevent or remove scale, operators often use oil well treatments with chemical scale inhibitors. These inhibitors, such as phosphonates or polyacrylates, interfere with the crystallization process. If scale has already formed, acidic treatments (like hydrochloric acid) are sometimes used to dissolve the deposits and restore proper flow.

2. Corrosion

Corrosion is a major concern for wells, especially those that are producing sour crude (oil with high hydrogen sulfide content). The corrosive agents – hydrogen sulfide (H2S) and carbon dioxide (CO2) – can cause the steel equipment in the well to weaken, leading to potential equipment failure and leaks. Wells that contain both H2S and CO2 are extremely susceptible to steel failures. Those failures will and can occur on either the tubing or the casing.

Treatment: To manage corrosion, operators typically use corrosion inhibitors. These chemical compounds form a protective film on metal surfaces to prevent the corrosive agents from reacting with the metal. Another common treatment is cathodic protection, which uses an electrical charge to prevent metal deterioration.

3. Hydrate Formation

Hydrates are ice-like solid structures that form when water and gas (such as methane) mix at low temperatures and high pressures. These can block the flow of oil or gas, creating significant operational challenges. Hydrates are particularly problematic in offshore wells, where temperatures are cooler and pressure conditions are higher.

Treatment: The most effective oil well treatments for dealing with hydrates feature the injection of methanol or glycol. These chemicals prevent hydrate formation by lowering the freezing point of water. In addition, thermodynamic inhibitors and electric heaters can be used to dissolve existing hydrates and prevent their reformation.

4. Wax Deposition

Wax deposition is another issue that affects wells, particularly in areas where the crude oil has a high paraffin content. When the oil cools, paraffin wax can precipitate and deposit along the wellbore, pipelines or downhole equipment. Pressure drops can also accelerate the buildup of paraffin. Wax buildup reduces the flow of oil and can lead to blockages.

Treatment: To combat wax formation, chemical wax inhibitors or dispersants are often injected into the well to reduce the rate of wax precipitation. Mechanical solutions, such as pigging (using mechanical devices to scrape away deposits), can also be employed to clear out accumulated wax.

5. Bacterial Growth

Bacteria, including sulfate-reducing bacteria (SRB), can thrive in oil wells, particularly in water that comes into contact with hydrocarbons. These bacteria consume hydrocarbons and produce H2S, which is highly corrosive and can further damage well infrastructure.

Bacteria can thrive in oil wells and produce corrosive hydrogen sulfide.

Treatment: Biocides are commonly used to kill harmful bacteria in the wellbore. These chemicals can be injected into the well to treat microbial contamination and prevent the formation of H2S.

6. Sand Production

In certain oil reservoirs, sand production is a problem. When the producing formations in the well become unstable or the pressure changes, sand grains can be carried to the surface along with the oil. This can cause equipment erosion, clogging and even damage to production facilities.

Treatment: To control sand production, operators may use sand control techniques like gravel packing or installing screens. In some cases, chemical treatments like polymer-based sand stabilizers can be injected into the well to prevent sand migration.

Oil well treatments are a vital part of the maintenance plan for many wells to keep them running smoothly and efficiently. From scale formation and corrosion to hydrate issues and bacterial growth, a variety of challenges can arise over the lifetime of an oil or gas well. Thankfully, there are numerous treatments that can address these issues and restore optimal flow. However, the effectiveness of well treatments is contingent upon the needed chemicals being able to reach the affected area. That effort can be hindered if downhole equipment, particularly standard B2 tubing anchors, is restricting the flow of fluid through the annulus of the well.

Maximizing the Effectiveness of Oil Well Treatments with the Slimline TAC

One way to ensure the best possible reach of the chemicals in oil well treatments is to use the Slimline® Tubing Anchor Catcher from TechTAC® when anchoring a production string. The Slimline design creates increased flow area between the anchor OD and the casing ID (up to 245% more than a standard B2 anchor). That increased annular area allows a larger volume of treatment chemicals to flow past the anchor at a higher velocity, while not creating a chokepoint that causes a restrictive flow.

The top of a 55STAC-C

In addition, the need for chemical treatments is often reduced in wells that run Slimline anchors. A recent CFD study found that the net pressure drop around a standard Baker B2-style tubing anchor, as fluid and gas passes through the annular cavity around the anchor, is more than double the pressure drop around the Slimline TAC. A significant pressure drop, like that around the standard anchor, is a major contributor in the formation of scale, iron sulfide and paraffin – some of the very substances well treatments are used to remove. To learn more about the TechTAC’s suite of tubing anchors, including the Slimline TAC, download the company’s product catalog or contact our team!

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