Oil casing, commonly referred to as casing, is a type of oil country tubular goods (OCTG). OCTG includes various components such as finished oil casing, oil tubing, drill pipe, drill collars, couplings, sucker rods, and pup joints. Today, we will explore the classification and functions of oil casing pipes, providing a clearer understanding of their roles in drilling operations.  Drilling Guide Bush: The drilling guide bush is primarily used in offshore and desert drilling environments. Its main purpose is to separate seawater and sand, ensuring smooth drilling operations. This casing layer is typically manufactured with specifications of ∮762mm (30in) × 25.4mm and ∮762mm (30in) × 19.06mm. It plays a vital role in maintaining wellbore stability during the early stages of drilling, especially in challenging geological conditions.  Surface Casing: Surface casing is installed during the initial phase of drilling to pass through soft ground layers and reach the bedrock. It prevents formation collapse and ensures proper sealing. Common sizes for surface casing include 508mm (20in), 406.4mm (16in), 339.73mm (13-3/8in), 273.05mm (10-3/4in), and 244.48mm (9-5/9in). The depth of installation varies depending on the soft formation's depth, usually ranging from 80 to 1500 meters. Surface casing is generally exposed to lower internal and external pressures, so it often uses K55 or N80 steel grades.  Technical Casing: Technical casing is used when drilling through complex formations, such as unstable layers, oil, gas, water zones, lost circulation zones, and salt-gypsum layers. If these layers are not properly sealed, they can cause serious drilling complications. In deep or highly complex wells, multiple technical casing strings may be required, demanding high mechanical strength and excellent sealing performance. Commonly used steel grades include N80 and P110, while deeper wells may use non-API grades like Q125 or V150. Technical casing specifications typically include 339.73mm (13-3/8in), 273.05mm (10-3/4in), 244.48mm (9-5/8in), 219.08mm (8-5/8in), 193.68mm (7-5/8in), and 177.8mm (7in).  Oil Layer Casing: Once the target oil or gas layer is reached, oil layer casing is used to isolate the hydrocarbon zone and the overlying strata. As the deepest casing string in most wells, it requires the highest level of mechanical strength and sealing capability. Steel grades commonly used for oil layer casing include K55, N80, P110, Q125, and V150. Typical dimensions include 177.8mm (7in), 168.28mm (6-5/8in), 139.7mm (5-1/2in), 127mm (5in), and 114.3mm (4-1/2in), among others. Proper selection of casing is crucial to ensure long-term well integrity and efficient production. EVA fish bag,EVA Live Bait Bucket,Fishing Tackle Bucket,Lce Fishing Bucket Bag Langfang Jinzhao Sports Products Co., Ltd , https://www.jinzhaowenti.com