How nickel alloys can extend well life in Haynesville by preventing corrosion EVEN WITH LIMITED CAPEX.
Nickel alloys offer a game-changing solution for extending well life in the Haynesville Basin, particularly in deeper HPHT (high-pressure, high-temperature) gas wells with higher corrosion risks. Even with limited CAPEX, transitioning to Nickel OCTG (oil country tubular goods) can deliver significant long-term benefits.
Historically, operators in the Haynesville Basin have relied on 13Cr and Super 13Cr alloys, which performed adequately in shallower wells. However, as drilling activity reaches deeper HPHT environments, increasing levels of H2S are being encountered. Investing in higher CAPEX for HPHT casings made from nickel alloys may seem daunting in today’s market. However, a thorough risk analysis shows that nickel tubulars provide superior corrosion resistance, ensuring better well reliability and overall cost-efficiency.
Key Benefits of Nickel Tubulars for HPHT Wells:
Extended Well Life: Nickel OCTG significantly reduces corrosion, minimizing the need for repairs or replacements during the well’s lifetime.
Improved Production and Cash Flow: By reducing downtime, nickel tubulars improve production rates and enhance long-term financial performance.
Reduced Workovers: Workovers are costly and risky, but nickel tubulars limit their necessity by improving casing durability in HPHT conditions.
Enhanced Safety and Environmental Protections: Reliable HPHT casings reduce the risk of critical equipment failure, lowering the chances of expensive EH&S (Environmental, Health, and Safety) incidents.
Support for Growing LNG Export Demand: With the increasing demand for clean energy, reliable nickel alloy production ensures operators can meet export quotas without interruptions.
Optimize Well Design with Corrosion Resistant Alloys
PipeSearch facilitator Corrosion Resistant Alloys (CRA) offers specialized technical support to help operators in the Haynesville Basin select the most optimal HPHT alloy casing for their unique well scenarios. Our team works to maximize the performance of your Nickel OCTG investment while offering creative commercial solutions to effectively manage CAPEX.
Types, Applications, Item Descriptions, and Alloys
PipeSearch has invested significant resources, supported by industry experts and technology veterans, to develop a digital platform tailored to the needs of the OCTG market. This innovative product aims to enhance efficiency, sustainability, quality, and transparency in trading high-quality OCTG products.
What is OCTG?
OCTG, or Oil Country Tubular Goods, refers to tubes used in oil and gas production, both onshore and offshore, as part of the industry’s upstream sector. PipeSearch specializes in two essential types of OCTG products: casing and tubing. These components are critical to the completion and production of oil, gas, and injection wells. Understanding OCTG products is essential for oil and gas sector professionals.
What are the Differences Between Casing and Tubing?
OCTG pipe sizes are generally denoted by their outer diameter (OD) measurements, ranging from 2-3/8” to 20” OD.
OCTG Casing
OCTG casing stabilizes the wellbore by lining the borehole drilled into the ground for oil extraction. Typically larger in diameter, it is secured in place with cement. Casing sizes range from 4.5” to 20” OD and are vital in ensuring operational stability.
There are five primary types of oil well-casing pipes:
Conductor Casing: (18”–36” OD): Creates the initial barrier at the surface.
Intermediate Casing: (13-3/8”–16” OD): Positioned between surface and production casing for added support.
Production Casing: (varied sizes): Maintains structural integrity during hydrocarbon production.
Production Liner: Suspended from production casing to save costs by reducing full-depth liner use.
OCTG Tubing
OCTG tubing, available in sizes ranging from 2-3/8” to 4-1/2” OD (or larger, up to 7” in offshore wells), is inserted through the casing to transport hydrocarbons to the surface. Tubing protects the casing from corrosive fluids, sand, and other wear-and-tear factors. Unlike casing, damaged tubing can be replaced, offering flexibility and enhanced durability.
Understanding an OCTG Pipe Item Description
An OCTG item description follows industry standards to denote key pipe characteristics, typically stated in this order:
Outer Diameter (OD)
Weight per Foot
Alloy/Grade
Yield Strength
End Finish/Connection
Range (Length)
Example Item Description:
For instance, a description like 5.5” 23# 13CR-85 Vam Top HC R3 translates to:
Outer Diameter (OD): 5.5 inches
Weight Per Foot: 23 lbs/ft
Alloy/Grade: 13 Chrome (13CR)
Yield Strength: 85 ksi (85,000 psi)
End Finish/Connection Type: Vam Top HC
Range Style (Length): Range 3 (R3)
Standardization of OCTG Pipe Sizes
Industry organizations like the American Petroleum Institute (API) and the International Organization for Standardization (ISO) standardize OCTG pipe sizes for compatibility and interchangeability. Standards like API Specification 5CT define technical casing, tubing, and line pipes requirements.
Common Tubing Sizes: 2-3/8” 2-7/8” 3-1/2” 4” 4-1/2”
It’s important to note that these sizes are examples and not an exhaustive list. The exact range of standard outer diameters may vary based on specific API specifications or other industry standards. Additionally, there may be non-standard or custom sizes available based on project requirements.
What is Weight Per Foot in OCTG?
The weight per foot is a key parameter impacting OCTG product design, installation, and transportation. It is calculated using the following formula:
Weight per foot (lbs/ft) = [(OD – Wall Thickness) x Wall Thickness] x 10.69
In this formula, the outer diameter (OD) and wall thickness are usually expressed in inches. The resulting weight per foot will be in pounds.
It’s important to note that the weight per foot can vary for different sizes and grades of OCTG. The specific weight per foot values can be obtained from product specifications, manufacturers’ catalogs, or industry references for the specific OCTG casing or tubing you are interested in.
Overview of OCTG Alloys and Grades
OCTG casing and tubing are designed to withstand the downhole conditions of a well. The alloy/grade of the OCTG describes the actual chemical composition and mechanical properties of the material. Different alloys or grades are better suited to various downhole environments, or are designed to withstand more extreme conditions, such as high pressure, corrosive environments, and varying temperatures.
It is important to note that the American Petroleum Institute (API) and the National Association of Corrosion Engineers (NACE) which is now called the Association for Materials Protection and Performance (AMPP), have set standards and specifications for OCTG casing and tubing to ensure their quality and performance. The specific alloy selection depends on factors such as well depth, pressure, temperature, corrosiveness of the formation, and other operational requirements.
The commonly used alloys and grades for OCTG casing and tubing can be categorized into five general groups based on their resistance to environmental factors. These groups, listed in order of increasing environmental resistance, are Carbon Steel, Chromium-molybdenum (Cr-Mo) Alloys, Martensitic Stainless Steel, Duplex Stainless Steel, and Nickel-Based Alloys.
Carbon Steel Grades
Carbon Steel grades are generally the most cost-effective option and are suitable in non-corrosive environments. They are often used in shallow wells with relatively low pressure, downhole conditions where the corrosive potential is minimal, and temporary applications where components may be removed after the initial phase or long-term production is not expected, therefore the long-term corrosion resistance of higher-grade materials may not be necessary. Carbon steel alloys include J55, K55, N80, L80, and P110.
Chromium-Molybdenum Alloys
Chromium-Molybdenum (Cr-Mo) Alloys have a higher tensile strength and resistance to sulfide stress cracking under certain conditions. They are commonly used in mildly sour and slightly deeper wells. These alloys include C95 and C110.
Martensitic Stainless Steels
Martensitic Stainless Steels are used extensively in sweet (CO2) environments where carbon and low alloy steels experience general corrosion, and are acceptable for moderate sour service conditions. They range in yield strength from 80 to 125 ksi, achieved by quench and temper heat treatment. 13 Chrome is the least alloyed of the stainless steels and most common for OCTG. These alloys include 13 Chrome, Modified 13 Chrome, Super 13 Chrome, 15 Chrome, and 17 Chrome.
Duplex Stainless Steels
Duplex Stainless Steelsare required in sweet (CO2) environments containing chlorides or dissolved ocygen, where pitting and crevice corrosion are a concern. Cold-worked tubes are available with with yield strengths up to 140 ksi.
Super Duplex Stainless Steels
Super Duplex Stainless Steelsextend the useful range of temperature and chlorides. Defined by Pitting Resistance Equivalent Number (PREN) greater than 40, they are recommended for conditions with high chlorides or dissolved oxygen, such as seawater and water injection wells. Duplex Stainless Steel alloys include 22 Chrome Duplex, 25 Chrome Duplex, and Super Duplex.
Nickel-Based Alloys
Nickel-Based Alloys are used primarily in sour environments where the partial pressure of H2S exceeds 3 psi. Their useful range of temperature, H2S, and chlorides is extended by increasing additions of nickel, molybdenum, and other elements. Solid solution nickel based alloys are available as cold worked tube with yield strengths up to 160 ksi. In addition to excellent resistance to chlorides and H2S, they eliminate the risk of hydrogen embrittlement which may occur with heat treated alloys. Nickel based used in OCTG casing and tubing include 28 Chrome, 2535, 2035, 825, G3, G2, 2550, G50, C276, and C22.
What is Yield Strength in OCTG?
Yield strength, in relation to OCTG, refers to the maximum stress or load that a material can withstand before it undergoes deformation or starts to exhibit plastic behavior. It is an essential mechanical property that indicates the material’s ability to resist deformation under applied stress.
Yield strength is typically measured using a tensile test, also known as a tension test. This test involves subjecting a specimen of material, such as a small section of OCTG casing or tubing, to an applied force or lead in tension until it undergoes deformation.
During the tensile test, the specimen is placed in a testing machine, commonly known as a universal testing machine. The machine applies a gradually increasing tensile force to the specimen, causing it to elongate until it reaches the point of yield. The force and the resulting elongation or deformation are continuously measured throughout the test.
Once the yield strength is determined, it serves as a parameter useful in assessing its suitability for various well conditions and it’s ability to withstand applied loads and pressures in oil and gas wells. The yield strength value is typically reported in units of force per unit area, such as pounds per square inch (psi) or 1,000 pounds per square inch (ksi). Generally, the higher the yield strength the greater the ability to withstand applied loads, higher pressures, more severe downhole conditions.
What is an OCTG Connection?
The connection refers to the machined finish on the ends of each joint or piece of OCTG that allows the pieces to connect to one another to form a string of pipe in the well. OCTG pipe connections are leak-proof, strong, durable designs that fall into three general categories: API, Semi-Premium, and Premium.
API connections meet or exceed all American Petroleum Institute (API) specifications. Semi-Premium connections are similar to API but are engineered for enhanced torque. Premium connections provide performance beyond standard API connections and are engineered to produce a gas-tight metal-to-metal seal.
In terms of connection design, there are various types of connections. Thread manufacturers have engineered a number of proprietary threads within these types to best serve specific applications. The general types can be categorized as the following: Threaded and Coupled (T&C), Semi-Flush, and Flush.
A threaded and coupled connection uses a threaded coupling to join two threaded ends of pipe. A semi-flush connection has a slight upset and lacks a coupling so one threaded pin end fits into one threaded box end. A flush connection lacks an upset and a coupling where one threaded pin end fits flush into one threaded box end. This is desirable when clearances are limited downhole and there is nothing additional on the OD to accommodate a coupling or upset end.
OCTG can also be acquired with plain ends or without connections. Of course, it cannot be used downhole until it is threaded.
OCTG Pipe Ranges
OCTG length is typically categorized using Ranges. These designations differ slightly between casing and tubing.
Tubing Ranges: Range 1 (R1) is 20-25 feet, Range 2 (R2) is 28-32 feet, and Range 3 (R3) is 38-45.
Casing Ranges: Range 1 (R1) is 16-25 feet, Range 2 (R2) is 25-34 feet, and Range 3 (R3) is 34-48.
The range pipe required for adequate well completion is dependent upon various factors including rig capabilities, well depth and well design. If the rig can accommodate longer lengths, however, Range 3 pipe may be most desirable as it reduces the number of needed connections.
In conclusion, OCTG casing and tubing plays a vital role in the completion and production of oil, gas, and injection wells. Casing and tubing each have a specific purpose and general application. Item descriptions help to differentiate between products, and alloys and connections are vital to operation downhole.
Partnering with a Trusted OCTG Pipe Supplier
Choosing a reliable OCTG pipe supplier ensures consistent quality and adherence to API standards, which are essential for smooth oil and gas operations. PipeSearch provides a streamlined platform with carefully curated options, giving your operations a competitive edge.
When managing acid gas injection (AGI) wells, water in acid gases can create highly corrosive conditions. While low-alloy steels are commonly used in “dry” AGI wells—those designed to be “water-free”—there are instances where low compressor discharge temperatures can lead to water formation even in these supposedly dry environments. Additionally, casing and tubing are often exposed to groundwater below the packer, exacerbating corrosion risks.
While stainless steels may resist corrosion caused by CO2, they often fail to handle the high partial pressures of H2S typically found in acid gases. A nickel alloy is highly recommended for such applications to ensure adequate corrosion resistance.
For environments with temperatures below 270°F, 2535 nickel alloy has proven to be a reliable solution.
For higher temperature conditions, 2550 nickel alloy offers exceptional performance.
PipeSearch offers a wide range of high-performance alloys tailored for the harsh environments of Acid Gas Injection, which are available for quick release. Our corrosion-resistant materials are carefully selected to meet the unique challenges of AGI corrosion. Contact us today to explore high-quality solutions for your acid gas injection needs.
A visual thread inspection (VTI) is a critical process conducted to evaluate the condition of pin and box end threads and identify potential hazards or thread damage. During a VTI, protectors are removed, threads are cleaned, dried, and then examined by a trained professional. This inspection determines whether repairs or rethreading are necessary to ensure thread integrity and prepare the connections for use. While a damaged thread doesn’t automatically condemn the pipe, the time and cost required to rethread may render it impractical for certain applications. Here are eight common hazards identified during a VTI, particularly for premium thread connections and OCTG threading:
Key signs: Heavy galling on the front half of the connection indicates severe damage.
1. Thread Galling
Thread galling is a type of wear caused by friction and adhesion between sliding metal surfaces. It leads to visible material transfer, appearing as raised lumps called “galls.” Galling often occurs rapidly when insufficient lubrication between metal surfaces in contact, particularly during threading pipe in place.
Key signs: Scratch located within the sealing area, visible above the marked white line.
2. Scratches On Threads
Scratches vary in severity depending on their depth, location, and extent. Minor scratches are often repairable without compromising thread integrity. However, deeper scratches, especially in the sealing area, can be critical since this area must remain free of defects like rust, pits, or burns.
Key signs: Burrs visible on the seventh thread.
3. Thread Burrs
Burrs are rough edges or ridges caused during the manufacturing or thread-cutting process. These appear at the pipe ends; the thread starts, or further along the threading. Depending on the severity, deburring techniques may preserve the OCTG threading.
Key signs: Mashed threads identified within the highlighted white circle.
4. Mashed Threads
Mashed threads result from external forces reshaping or flattening the threaded surface. Proper threads have a defined and precise structure, whereas mashed threads appear smooth or flattened.
Key Signs: Dark crests on threads from the seventh thread onward.
5. Unfinished Threads
Unfinished threads are identified by dark, incomplete sections along the thread crest. This happens when the tube isn’t perfectly straight during the threading process, preventing the carbide insert from making full contact with the tube. Unfinished threads fail to provide an adequate seal and can lead to thread galling.
Key Signs: Rust visible across multiple sections of the threading.
6. Rust on Alloy Threads
Rust, a common form of corrosion, typically results from improper storage or maintenance of threaded connections. The correct application of thread compounds, such as Kendex, is a moisture barrier and corrosion inhibitor to protect premium thread connections.
Key Signs: Pronounced pits visible on the second thread crest.
7. Pitting on Threads
Pitting is a type of corrosion that creates cavities or holes (pits) on the pipe surface. These defects act as stress risers, compromising the threading pipe in place if not appropriately handled. Left untreated, pits can grow into deep cavities or through-wall holes, impacting thread integrity.
Key Signs: Copper flaking at the connection’s rear and tarnished threads throughout.
8. Flaking on Copper Alloys
Premium connections often include copper-coated threads on boxes or couplings to prevent galling during repeated use. If not maintained, the copper coating tarnishes and flakes off, exposing the underlying steel surface. Flaking on the sealing area may necessitate re-copper plating to safeguard the connection’s integrity.
Safeguard Your Thread Connections with Proper Maintenance
Understanding and addressing these hazards ensures the longevity and functionality of OCTG threading and other premium thread connections. Regular VTI inspections are pivotal in protecting thread integrity and extending the life of your pipe threading. Always consult professionals for inspections and remediation to maintain reliable connections.
Galvanic corrosion, also known as bimetallic corrosion, occurs when two dissimilar metals come into contact in the presence of an electrolyte. This electrochemical reaction is driven by the difference in electropotential between the metals, like the process within a battery.
How Galvanic Corrosion Happens
When galvanic corrosion occurs, ions migrate from the less noble metal (the anode) to the more noble metal (the cathode). However, for this process to take place, two conditions must be met:
Presence of an electrolyte
Electrical contact between the metals
Packer or production fluids often serve as electrolytes within oil and gas production. Fluids with low conductivity, like oil-based packer fluids, pose minimal risk. However, water-based packer and acidizing fluids, which are stronger electrolytes, present a greater concern for galvanic corrosion.
Factors Influencing Galvanic Corrosion
Several factors impact the severity and likelihood of galvanic corrosion, particularly in systems involving nickel pipe, steel casing, or nickel casing.
Electropotential Difference: The greater the electropotential difference between two metals, the higher the corrosion rate in the anode. However, this isn’t solely determined by the metal alloy—it is also influenced by the surrounding environment, surface conditions, and protective films.
Surface Films and Scale: Corrosion inhibitors and natural surface films can act as insulators, reducing the risk of galvanic corrosion. For example, Nickel-based alloys and stainless steels often form passive surface films in oxidizing environments, preventing corrosion. However, under reducing conditions (e.g., during acidizing), these protective films may break down, increasing the risk of accelerated galvanic corrosion.
Cathode-to-Anode Surface Area Ratio: A high ratio of cathode surface area to anode surface area can accelerate corrosion at the anode. This effect is critical to consider in the design and maintenance of oil and gas production equipment.
Why Galvanic Corrosion Is a Concern in Oil & Gas Production
Different metals are common in oil and gas systems, creating frequent opportunities for galvanic corrosion. Here are some key examples:
Mixed tubing strings
Nickel pipe or nickel casing components in contact with steel casing
Nickel alloy accessories used alongside stainless steel tubing
Prolonged exposure to harsh conditions like water-based packer fluids or acidizing environments can further heighten the risk of galvanic corrosion, leading to equipment degradation and increased maintenance costs.
By understanding how galvanic corrosion develops, its influencing factors, and common scenarios in oil and gas production, operators can take preventative measures, such as using corrosion inhibitors and selecting the right materials to extend the longevity of equipment.
Sustainability isn’t just a buzzword—it’s a priority across industries and around the globe. More than ever, people ask how the companies they support contribute to a sustainable future. Cole Patchell, President of PipeSearch, shares how the company is making a meaningful impact.
At PipeSearch, sustainability is a core value driving everything we do. We believe in “building it right” and are committed to making a difference in business, the community, and the environment. Operating within the steel industry—a sector responsible for over 5% of global CO2 emissions—gives us both a challenge and an opportunity to create tangible, positive change.
One of our key contributions is reducing CO2 emissions by reallocating and recycling surplus Oil Country Tubular Goods (OCTG) and Nickel OCTG. By prioritizing using these existing materials, we minimize the need to manufacture new pipe, which significantly curtails CO2 emissions.
Over the past year, PipeSearch has also actively participated in several carbon capture and storage (CCS) and carbon capture, utilization, and storage (CCUS) projects. These initiatives can potentially reduce CO2 emissions from power plants by over 85%. By supplying reallocated and recycled pipe for such projects, we’re contributing to cleaner air and a sustainable future.
Through our efforts, PipeSearch is proud to show that surplus OCTG and Nickel OCTG can drive efficiency and promote environmental stewardship. Whether mitigating CO2 corrosion through innovative pipe use or driving impactful CCS and CCUS initiatives, PipeSearch is forging a greener, smarter path for the industry and beyond.
Together, we’re making sustainability a reality—one pipe at a time.
