Methods for Evaluating the Quality of Oilfield Tubular Inspections
Authors: Moyer M.C. , Dale B.A. 
Published: December 2007

This paper discusses methods and test procedures for conducting field evaluations to determine the effectiveness of oilfield tubular-inspection equipment and personnel. Specific requirements and equations are proposed for qualifying magnetic particle, ultrasonic, eddy current, radiographic, optical, and mechanical nondestructive test equipment. The design and use of pip standards to check automated pipe-inspection systems are also described. By incorporation of the methods pipe-inspection systems are also described. By incorporation of the methods developed in this paper, nondestructive inspection services can be qualified with respect to the pipe diameter, weight, grade, or critical application of the tubular.

Introduction

In drilling for oil and gas, we are encountering ever-increasing challenges in the form of more hostile environments. Higher pressures. greater temperatures, corrosive gases, and deeper, deviated wellbores present new problems. Because of these challenges, the quality of problems. Because of these challenges, the quality of tubulars that are used to complete the well becomes even more critical. The oil industry currently ensures the quality of new tubulars placed downhole through nondestructive inspections conducted in the field or at the pipeyard. The inspection equipment typically is designed to locate seams, laps, pill, slugs and thin-wall areas that result from the manufacturing process, as well as mechanical damage from handling. Oilfield tubulars are one of the most important factors that affect the production and safety of any oil or gas well. In particular, tubing and casing are subjected to high tension loads from the weight of the string, burst loads from internal production pressures, collapse loads from external formation pressures, bending loads from wellbore deviations, and other severe conditions, such as sour-gas environments. And finally, these tubulars may remain in production for as long as 20 years with corrosion taking production for as long as 20 years with corrosion taking its toll. The majority of today's oilfield tubulars are made of carbon or alloy steels and are manufactured by the seamless piercing and rolling process. The cost of these tubulars often represents 20 to 40% of the drilling program cost. but the cost of a tubular failure can be even more dramatic. Pipeyard inspection reports for new tubing and casing indicate that about 20% of domestic tubulars are rejected when held to API specifications. Therefore, the pipeyard inspection is critical in maintaining the quality pipeyard inspection is critical in maintaining the quality of the wellbore. Service companies provide tubular inspections for most oil companies. The quality of these inspections varies significantly from region to region. One of the principal reasons for this variation is a lack of specifications for the nondestructive testing (NDT) of oilfield tubulars. Once a specification has been established, the next step is to evaluate and to qualify the inspection company during field evaluations in that region. Existing NDT specifications, such as the American Soc. of Nondestructive Testing (ASNT), the American Soc. for Testing and Materials (ASTM), or API Specifications, are neither detailed enough nor directed specifically enough to the oil field to allow the inspection equipment to be evaluated and qualified to a particular level. The final step in among quality inspections is through adequate supervision and periodic audits of equipment and personnel. periodic audits of equipment and personnel. This paper addresses the specific performance levels for NDT equipment and personnel for oilfield tubular inspections. The requirements developed at Exxon Production Research Co. involve theoretical calculations, review Production Research Co. involve theoretical calculations, review of the existing inspection methodology, and experimental testing in electromagnetics, ultrasonics, and radiography. Then these requirements were incorporated into a procedure for conducting field evaluations to determine and to maintain the quality of oilfield tubular inspections.

Field Evaluations of Oilfield Inspection Operations

Field evaluations of an oilfield inspection operation consists of testing and documenting information in three principal areas: (1) automated pipe-body inspections, principal areas:automated pipe-body inspections,special end-area and prove-up inspections, andpersonnel certification and reference documents.

These areas are discussed individually and described in more detail to pert-nit field evaluations to be conducted. Performance specifications that serve as a basis for evaluating the quality of the inspections are described. When field evaluations are made, all pertinent information that describes the inspection equipment, personnel, and procedures should be recorded. Identification numbers should be assigned to the inspection equipment when no other identifiable markings exist to allow easy identification at a later date. This also serves as a list that describes the equipment available at the particular inspection site.

Automated Pipe-Body Inspections

The geometrically uniform section of the pipe (all but the last few feet from either end) typically is inspected by an automated inspection system capable of scanning pipe at about 1 ft/sec [0.3 m/s].

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