30 C.F.R. § 250.421 What are the casing and cementing requirements by type of casing string?
Title 30 - Mineral Resources
The table in this section identifies specific design, setting, and cementing requirements for casing strings and liners. For the purposes of subpart D, the casing strings in order of normal installation are as follows: drive or structural, conductor, surface, intermediate, and production casings (including liners). The District Manager may approve or prescribe other casing and cementing requirements where appropriate. [68 FR 8423, Feb. 20, 2003]
Title 30: Mineral Resources
PART 250—OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF
Subpart D—Oil and Gas Drilling Operations
Casing and Cementing Requirements
§ 250.421 What are the casing and cementing requirements by type of casing string?
------------------------------------------------------------------------ Casing Cementing Casing type requirements requirements------------------------------------------------------------------------(a) Drive or Structural......... Set by driving, If you drilled a jetting, or portion of this drilling to the hole, you must minimum depth as use enough cement approved or to fill the prescribed by the annular space District Manager. back to the mudline.(b) Conductor................... Design casing and Use enough cement select setting to fill the depths based on calculated relevant annular space engineering and back to the geologic factors. mudline. These factors Verify annular include the fill by observing presence or cement returns. absence of If you cannot hydrocarbons, observe cement potential returns, use hazards, and additional cement water depths. to ensure fill- Set casing back to the immediately mudline. before drilling For drilling on an into formations artificial island known to contain or when using a oil or gas. If glory hole, you you encounter oil must discuss the or gas or cement fill level unexpected with the District formation Manager. pressure before the planned casing point, you must set casing immediately.(c) Surface..................... Design casing and Use enough cement select setting to fill the depths based on calculated relevant annular space to engineering and at least 200 feet geologic factors. inside the These factors conductor casing. include the When geologic presence or conditions such absence of as near-surface hydrocarbons, fractures and potential faulting exist, hazards, and you must use water depths. enough cement to fill the calculated annular space to the mudline.(d) Intermediate................ Design casing and Use enough cement select setting to cover and depth based on isolate all anticipated or hydrocarbon- encountered bearing zones and geologic isolate abnormal characteristics pressure or wellbore intervals from conditions. normal pressure intervals in the well. As a minimum, you must cement the annular space 500 feet above the casing shoe and 500 feet above each zone to be isolated.(e) Production.................. Design casing and Use enough cement select setting to cover or depth based on isolate all anticipated or hydrocarbon- encountered bearing zones geologic above the shoe. characteristics As a minimum, you or wellbore must cement the conditions. annular space at least 500 feet above the casing shoe and 500 feet above the uppermost hydrocarbon- bearing zone.(f) Liners...................... If you use a liner Same as cementing as conductor or requirements for surface casing, specific casing you must set the types. For top of the liner example, a liner at least 200 feet used as above the intermediate previous casing/ casing must be liner shoe. cemented If you use a liner according to the as an cementing intermediate requirements for string below a intermediate surface string or casing. production casing below an intermediate string, you must set the top of the liner at least 100 feet above the previous casing shoe..------------------------------------------------------------------------
