Old and Modern Well Log Data and Its Reliability Through a Novel Certification Process

Abstract

The main objective of this paper is to present acertification process to achieve the reliability of well log data for any user, independently where or when the log was ran. For example, the analogical log data (old data) is digitally recaptured and processed through quality control criteria's, edited and spliced curve by curve, where all technical steps are documented in the corresponding digital file in order to provide the user the details of how the technical process was used and made. Finally, a digital signature certifies all files. At that moment anyone can use the certified products for interpretations, correlations or petrophysical evaluations. As it is the case in most oil producing companies, two log data generation are present in Mexico: analogical and digital. Analogical process was initiated in 1904, when the first well was drilled, and the digital process began in 1979 through the "Cyber System Unit" used by Schlumberger. Those two generations, analogical and digital log data, demand new technologies and process to equalize the quality of old and modern data in order to use and manage this information in applications and databases. The certification process includes on line log inventory using the log and services codification published by The American Petroleum Institute (API), log quality control routine for "Digital Log Interchange Standard" (DLIS), "Log Information Standard" (LIS) and "Log ASII Standard" (LAS), including: originals, edited and spliced logs. The authenticity and reliability of each file is warranted by a digital signature, it specifies who made the process and who accepted the final product. The certification process was designed to equalize the quality of analogical and digital log generations, to establish the log reliability for any user and, finally to improve the data management. All these factors impact positively log data base preparation for project execution. Past, present and future of well log data On September 5th, 19271, when Schlumberger brothers run the first electric log in a well in France's Pechelbronn field, began the well logging era to nowadays. Afterwards, many kinds of logs and logging technologies have been developed in order to obtain more information and details from the subsurface. Now, two well differenced log data generation are present: analogical and digital. Many efforts have been done in order to equalize the analogical generation into digital data in terms of formats and quality controls. To support this goal, the main scope of this initiative is to provide all logs: open and cased hole, to any user in terms of integrity and reliability allowing the users to use those directly, including master log inventory; original, edited and spliced well log data. All products in this process have to be validated for the processor and certified for the data owner. As this process is applied over preexistent log data, it has to be applied over new log data (new acquisition) in order to guarantee similar standards for both log data generations. Finally all logs from a present or future well are conceived as an integrated product where the analyst can use the master inventory and download the certified data that he/she requires for his / her technical activities. Figure 1 shows the general certification process and its products. Well log data Certification Process The general certification process includes open and cased well logs; however, for this paper only open hole logs will be considered. The General Certification Process (Figure 1), includes the following sub process:Certification Process for analogical log data. (Figure 2)Certification Process for digitally captured log data: LAS format (Figure 3) Certification Process for digital origin data: LIS / DLIS format (Figure 4)