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In larger diameters, this annular pressure is small, rarely exceeding 200 psi (13.79 bar). In smaller diameters, it can be 400 psi (27.58 bar) or higher. Backpressure or pressure held on the choke further increases bottom hole pressure, which can be estimated by adding up all the known pressures acting in, or on, the annular (casing) side.
The purpose of surface casing is to isolate freshwater zones so that they are not contaminated during drilling and completion. Surface casing is the most strictly regulated due to these environmental concerns, which can include regulation of casing depth and cement quality. A typical size of surface casing is 13 + 3 ⁄ 8 inches (340 mm). [5]
Annular capacity (bbl/ft) = (ID hole 2 - OD pipe 2) / 1029.4. where ID hole 2 = Inside diameter of the casing or open hole in inches OD pipe 2 = Outside diameter of the pipe in inches. Similarly Annular volume (bbls) = Annular capacity (bbl/ft) × length (ft) and Feet occupied by volume of mud in annulus = Volume of mud (bbls) / Annular ...
Production casing is the final casing string set in a well and usually reaches from the surface to Target Depth (TD). The type of casing used depends upon the different conditions in the well. Commonly, production casing sizes range from 4 + 1 ⁄ 2 in (110 mm) to as large as 9 + 5 ⁄ 8 in (240 mm). It is the last string cemented in a well ...
In a completed well, there may be many annuli. The 'A' annulus is the void between the production tubing and the smallest casing string. The 'A' annulus can serve a number of crucial tasks, including gas lift and well kills. A normal well will also have a 'B' and frequently a 'C' annulus, between the different casing strings.
CCL – casing collar locator (in perforation or completion operations, the tool provides depths by correlation of the casing string's magnetic anomaly with known casing features) CCLBD – construction / commissioning logic block diagram; CCLP – casing collar locator perforation; CCLTP – casing collar locator through tubing plug
The top of the casing string and annulus is usually sealed. The most common size of casing hanger is 13 + 3 ⁄ 8 in (340 mm) with over 155,000 such units installed worldwide in 2014 alone. The contraction of the oilfield industry throughout 2015 meant that this figure was reduced somewhat to just under 120,000 units, of which 36,822 were "Pos ...
Well cementing is the process of introducing cement to the annular space between the well-bore and casing or to the annular space between two successive casing strings. [1] Personnel who conduct this job are called "Cementers".