Material and Properties
-
Acid brittleness is also known as SSC, Sulfide Stress Cracking or Hydrogen Embrittlement. It is a spontaneous brittle failure of high strength allow or steel in presence of humid hydrogen sulfide. When susceptible alloys or steel comes in contact with Hydrogen Sulfide, the chemical reaction makes metal sulfide and releases atomic hydrogen. Atomic hydrogen can combine to result in H2 which disperses into metal matrix taking up more space and weakening the bonds between the grains of metal. Formation of molecular hydrogen causes sudden failure due to cracking under tensile stress. This failure is generally limited to steels or alloys having a hardness of 22 or greater on the Rockwell C scale.
-
Axial strength is a function of cross sectional area of the tubular and Yield Strength of the material. It is calculated by the formula; Fy = π/4*(D2 – d2)*Yp. Axial Strength is an important factor while designing the well to determine the depth to which certain tubular can safely be run.
-
Corrosion is the deterioration of metals due to chemical reaction. Most common form of corrosion is through oxidization of metal surfaces. Most metals tend to lose electrons to oxygen in the air or in water. This process results in an oxide with the metal and cause deterioration of metal surface. When oxidation takes place due to different metal in contact with one another, it is called galvanic corrosion. Electrolytic corrosion takes place in electronic equipment when water or moisture gets trapped between two electrical contacts.
-
Corrosion coupons are metal strips that are used for measuring rate of corrosion in a system. Pre-weighed strips are installed in the coupon rack. The corrosion rate in a specific operating system is measured by comparing the initial weight with the weight of the strips after the test period of 60, 90 or 120 days as planned. Measurement of corrosion rate helps in planning maintenance, repair needs and also to assess material failure possibilities.
-
CRA is abbreviation of 'Corrosion Resistant Alloy'. CRA material should be considered whenever there is potential presence of water, particularly when combined with CO2, H2S or chlorides. CRA are metal alloys engineered to resist degradation of metal surface in corrosive environment. Stainless steel is commonly used CRA and provides resistance to corrosion. Stainless steel with varying percentages of Chromium, Nickel, and Molybdenum are used in oil & gas wells depending on corrosivity assessments in the application.
-
Hydrogen Embrittlement is also known as SSC, Sulfide Stress Cracking or acid brittleness. It is a spontaneous brittle failure of high strength allow or steel in presence of humid hydrogen sulfide. When susceptible alloys or steel comes in contact with Hydrogen Sulfide, the chemical reaction makes metal sulfide and releases atomic hydrogen. Atomic hydrogen can combine to result in H2 which disperses into metal matrix taking up more space and weakening the bonds between the grains of metal. Formation of molecular hydrogen causes sudden failure due to cracking under tensile stress. This failure is generally limited to steels or alloys having a hardness of 22 or greater on the Rockwell C scale.
-
NACE is the abbreviation of 'National Association of Corrosion Engineers'. NACE is globally recognized as a premier authority for corrosion control solutions. NACE was established in 1943 with headquarter in Houston, Texas, USA and has centres all across the globe. NACE offers training & certifications and also sets industry standards for corrosion control. NACE also has journals, publications and holds conferences to assist industry in effectively addressing corrosion prevention and control in the industry.
-
Sulfide Stress Cracking is also known as SSC, Hydrogen Embrittlement or acid brittleness. It is a spontaneous brittle failure of high strength allow or steel in presence of humid hydrogen sulfide. When susceptible alloys or steel comes in contact with Hydrogen Sulfide, the chemical reaction makes metal sulfide and releases atomic hydrogen. Atomic hydrogen can combine to result in H2 which disperses into metal matrix taking up more space and weakening the bonds between the grains of metal. Formation of molecular hydrogen causes sudden failure due to cracking under tensile stress. This failure is generally limited to steels or alloys having a hardness of 22 or greater on the Rockwell C scale.
-
Yield strength is the value of stress above which an irreversible plastic deformation would occur. All drilling tubulars have a defined yield strength based on the material used for manufacturing them. Yield strength is an important property which is used for selecting tubulars while designing a well.