Developing a quality assurance and quality control (QA/QC) plan is an important element of any surveillance logging program. A QA/QC plan is used to document how quality assurance (QA) and quality control (QC) activities will be implemented during a program, project, or task1. A QA/QC Plan for a surveillance logging program can provide adequate and accurate information in assessing the level of pipe defects reported from casing inspection logs and can be used to record possible trends regarding the individual casing inspection tools. It may also analyze data to characterize errors in measuring tubular thickness as well as monitor tool accuracy and data interpretation.
Quality assurance is defined as those planned and systematic operations conducted to ensure that the operation and/or product meets specifications2. QA activities are designed to ensure that the data produced is the type and quality expected for the data being collected. QA activities may include auditing control procedures, developing a procedure for quality control checks, developing a procedure to ensure data quality, and identifying who is responsible for ensuring data quality. Quality assurance is generally the responsibility of the contractor.
The quality assurance part of a QA/QC plan should be designed to make everyone feel confident that a paper trail is available to determine whether there is a problem with an operation, product, or service. QA does not require a complicated endeavor requiring an enormous amount of time and paper work. QA can be incorporated as part of a normal routine3. QA should include QC activities that will ensure that the product or service will meet defined standards of quality.
Quality control is defined as all those planned and specific actions or operations necessary to produce a product or service that will meet specified requirements for quality2. QC activities are generally conducted by an operator to ensure data accuracy and completeness. To minimize the chance of making an incorrect decision, data of adequate quality must be collected. QC programs can both lower the chances of making an incorrect decision and help the data user understand the level of uncertainty that surrounds a decision1. QC activities may include developing a procedure to verify data, developing a technical review process, reporting requirements, record management, and corrective actions. QC activities are generally designed to control the quality of a product or service as defined by the operator.
A QA/QC plan may consist of four major sections: project management, measurement and data acquisition, assessment, and data validation4. Some of the information that may be included in these sections are: project description, descriptions about the project organization and responsibilities, specific objectives for data collection and quality, procedures for obtaining samples, procedures for tool calibration and frequency, procedures for validating data and reporting, a procedure for a review report, and a procedure for implementing corrective action. A QA/QC plan can improve confidence in the data being generated, improve the data credibility with a contractor, and improve upon operational, product, or service efficiencies.
The following sections discuss the development of a quality assurance and quality control plan designed for a surveillance logging program. A surveillance logging program for gas storage may include running a casing inspection log to investigate or re-investigate the condition of downhole tubular goods. The purpose of this paper, a pipe defect may include casing corrosion, mill defects, or other pipe abnormalities. The QA and QC activities for monitoring and assessing information from casing inspection logs are discussed in this plan.