Digital Data Processing of Oilfield Production Data

Abstract

Abstract This paper is primarily concerned with relating time-proven digital data-processing techniques with a modern-day automatic lease production-control system. The system described is one recently installed in southeastern New Mexico. It is comprised of three remote batteries involving 150 producing wells (both flowing and pumping), 7 LACT units, 8 separate pay zones and 77 alarms, located 20 to 30 miles away from the central office. The connecting link between the central office and the three remote batteries is a leased two-wire telephone system. Several supervisory control functions are handled with this system in addition to transmitting and recording production data, e.g., individual-well test data, LACT data, tank gauge readings, various alarm conditions and other pertinent information. Application of Communications Equipment for Digital Data Processing Extensive use of communications equipment is providing oil producers with an efficient means for handling production data. Manufacturers are offering equipment with higher reliability, greater flexibility and lower over-all cost, which affords the application of such equipment for operation of lease systems. Frequency-shift tone equipment was selected as the communications medium for the system described in this paper. In this method of tone transmission a non-keyed or non-information condition represents a "space", or low-frequency tone, while an information pulse keys the transmitter to a "mark", or high-frequency tone. Either a "space" or "mark" signal is present on the transmission line at all times. Lack of either condition or a "no carrier" signal provides a fail-safe supervisory control function which causes the remote batteries to switch into "local control". The "no carrier" condition is indicated in the central office as an "error transmit" signal. Supervisory control or interrogation data are transmitted over the two-wire telephone system from the central office to the remote batteries by the use of a basic sequential-pulse-code system, wherein each control function is assigned a particular pulse-code arrangement. A "remote data selector" with selection of automatic or manual operation generates the DC-pulse code bits to key the frequency-shift tone transmitter for transmission of the proper supervisory control function. The frequency-shift receiving equipment at each remote location has matching frequencies to correspond with the transmitter frequency at the central office. Telemetering information or information on the measurement of quantitative variables is transmitted from each of the three remote batteries to the central office using tone transmitters of identical frequencies to match the receiving frequency of the frequency-shift tone receiver located in the central office. The telemetered data arrive in the central office in the form of an eight-channel coded paper tape. The ability to transmit the standard eight-channel code over a single tone channel is made possible by use of an eight-channel tape transmission machine which sends each bit of the eight-bit binary code in a determined sequence. In addition to regular tape transmission, this machine also has the ability to read and punch paper tapes. The supervisory control system of the communications link is so designed that a transmission failure at any one of the remote batteries, at the central office or of the actual two-wire line causes the batteries to switch into "local control". This feature provides a tremendous advantage for a data-processing system of this description, in that information is retained at the battery in the event of equipment or line failure of the communication link. Operation of Field Installations A system utilizing the equipment just described has recently been installed in Lea County, N. M. The system is made up of one central control and recording point located in Hobbs, N. M., with information telemetered from the separate battery installations located from 20 to 30 miles away. The batteries have different characteristics and, for purposes of description, will be referred to as Batteries A, B and C. Battery A Battery A is comprised of 106 producing wells, some flowing and some pumping, divided among nine different leases. JPT P. 1191^