ANSI API Spec 10D-2002(R2015) pdf free download.Specification for Bow-string Casing Centralizers
1 Scope
This standard provides minimum performance requirements, test procedures and marking requirements for bow-spring casing centralizers for the petroleum and natural gas industries. The requirements contained herein are limited, but are deemed adequate for use in oil field cementing. The procedures provide verification testing for the manufacturerÕs design, materials and process specifications, and periodic testing to confirm the consistency of product performance.
This standard is not applicable to rigid or positive centralizers.
2 Normative reference
The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards.
API Spec 5CT, Casing and Tubing ISOÊ 11960, Petroleum and natural gas industriesÊ Ñ Steel pipes for use as casing or tubing for wells
3 Terms and definitions
For the purposes of this standard, the following terms and definitions apply.
3.1 flexed
condition of a bow spring when a force three times the specified minimum restoring force (±Ê 5Ê %) has been applied to it
3.2 holding device
device employed to fix the stop collar or centralizer to the casing
EXAMPLES Set screws, nails, mechanical dogs and epoxy resins.
3.3 holding force
maximum force required to initiate slippage of a stop collar on the casing
3.4 hole size
diameter of the wellbore
3.5 restoring force
force exerted by a centralizer against the casing to keep it away from the wellbore wall
NOTE Restoring force values can vary based on installation methods.
3.6 rigid centralizer
centralizer manufactured with bows that do not flex
3.7 running force
maximum force required to move a centralizer through a specified wellbore diameter
NOTE Running-force values can vary depending on the installation methods.
3.8 standoff
smallest distance between the outside diameter of the casing and the wellbore
3.9 standoff ratio
ratio of standoff to annular clearance
NOTE It is expressed as a percentage.
3.10 starting force
maximum force required to insert a centralizer into a specified wellbore diameter
NOTE Starting-force values can vary depending on the installation methods.
3.11 stop collar
device attached to the casing to prevent movement of a casing centralizer
NOTE A stop collar can be either an independent piece of equipment or integral with the centralizer.
4 Requirements
4.1 Functions of a centralizer
The purpose of a casing centralizer is to facilitate running casing to the desired depth and to assist in centering the casing in the wellbore. One of the main objectives of centralizing a casing string is to facilitate a good cementing,thereby isolating fluids from different zones. A bow-spring centralizer can be constructed in various ways, using various types, shapes and quantities of bow spring.
4.2 Starting force
The maximum starting force shall be less than the weight of 12,19Ê m (40Ê ft) of casing of medium linear mass as defined in TableÊ 1 . The maximum starting force shall be determined for a centralizer in new, fully assembled condition.
4.3 Restoring force
The minimum restoring force for a 67Ê % standoff ratio shall not be less than the values shown in TableÊ 1. See A.2 for the derivation of the requirements.
4.4 Frequency of testing
4.4.1 Tests for design and process verification shall be performed for a minimum of six prototype centralizers. All of the tested centralizers shall conform to the performance requirements of TableÊ 1.
4.4.2 For confirmation of the consistency of product performance, testing shall be performed at least annually for each size of centralizer manufactured to this standard in quantities greater than 500 per year. Corrective action shall be implemented and documented for the centralizer size in question if the tested centralizer does not conform to the performance requirements of TableÊ 1.
