N80 material BTC offset ladder buckle 244.5mm oil casing high-strength anti collapse deep well operation special

Description :

  Oil casing is the lifeline that maintains the operation of oil wells, mainly used to protect the wellbore, isolate different formation fluids, and support Christmas tree equipment during drilling. This product is designed specifically for deep wells and complex geological conditions, using N80 steel grade material with excellent tensile strength and crush resistance. The BTC offset ladder thread connection method provides higher sealing and connection strength, effectively preventing high-pressure oil and gas leakage. The outer diameter of 244.5mm, combined with a wall thickness of 11.05mm, ensures structural stability in deep high-pressure environments. It is widely used for surface, technical, or production cementing operations in vertical, directional, and horizontal wells, solving the problems of wellbore collapse and fluid channeling.

  This oil casing is strictly produced in accordance with the API Spec 5CT international standard, with an outer diameter of 244.5 millimeters (9-5/8 inches), a wall thickness of 11.05 millimeters, and a single length typically within the 5-12 meter range specified by the API. The material used is N80 grade alloy steel, which has undergone quenching and tempering heat treatment. The yield strength reaches the range of 552-758 MPa, and the tensile strength is not less than 689 MPa. The thread processing adopts high-precision CNC lathe cutting to form BTC offset ladder buckle type, with uniform pitch, full tooth profile, strict taper control, ensuring efficient torque transmission and tight sealing surface fitting. Each casing undergoes hydrostatic testing, non-destructive testing, and geometric dimension inspection to meet the requirements of API Q1 quality management system, ensuring the reliability of the product under extreme working conditions.

  When selecting, the steel grade and wall thickness should be determined based on the well depth, formation pressure, and drilling fluid density. N80 steel grade is suitable for medium depth and medium load well sections, with higher strength than J55 and more economical than P110. Compared to circular threads (STC) and long circular threads (LTC), BTC inclined ladder buckles have a trapezoidal tooth shape that can withstand greater axial loads and bending stresses, making them particularly suitable for well sections with large dogleg angles or those that require deeper penetration. If the well condition involves highly corrosive media, additional consideration should be given to anti-corrosion coatings or the use of higher corrosion-resistant alloys; If it is an ultra deep well with ultra-high pressure environment, it is necessary to evaluate whether to upgrade to P110 or Q125 steel grade. Correctly matching specifications can avoid difficulties in lowering pipes or failure during service.

  During the installation process, it is necessary to strictly control the torque of the upper thread, use specialized thread grease to reduce friction and enhance sealing effect, and avoid incorrect or stuck threads. Before going down the well, check if the threaded protective cap is intact. When transporting and stacking, use a special bracket to prevent deformation of the pipe body or damage to the threads. The focus of daily maintenance is on rust prevention management during the inventory period. The storage site should be dry and ventilated, and regular inspections should be conducted to identify surface cracks or corrosion pits on the pipe body. Common faults include sealing failure caused by thread wear and local buckling of the pipe body. Therefore, smooth operation should be carried out during pipe lifting and lowering operations to avoid severe collisions. Reasonable maintenance can significantly extend the service life of oil casing, ensuring the efficiency and safety of oilfield production.

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