Computer-Based Downhole Data Acquisition and Transmission in Well Testing (1992)

Computer-Based Downhole Data Acquisition and Transmission in Well Testing A.F. Veneruso; A.F. Veneruso Eludes and Productions Schlumberger Search for other works by this author on: This Site Google Scholar C.A. Ehlig-Economides; C.A. Ehlig-Economides Eludes and Productions Schlumberger Search for other works by this author on: This Site Google Scholar A.M. Akmansoy A.M. Akmansoy Schlumberger Well Services Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Annual Technical Conference and Exhibition, Washington, D.C., October 1992. Paper Number: SPE-24728-MS https://doi.org/10.2118/24728-MS Published: October 04 1992 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Veneruso, A.F., Ehlig-Economides, C.A., and A.M. Akmansoy. "Computer-Based Downhole Data Acquisition and Transmission in Well Testing." Paper presented at the SPE Annual Technical Conference and Exhibition, Washington, D.C., October 1992. doi: https://doi.org/10.2118/24728-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Annual Technical Conference and Exhibition Search Advanced Search AbstractData acquisition techniques for computer-based systems are discussed for making continuous pressure, temperature and flow measurements. To ensure that the data faithfully represent the essential signal content over the time interval of interest, the important considerations for each system are measurement resolution, signal bandwidth, sampling, filtering and aliasing.Key data transmission techniques are discussed, starting with downhole recorders that must be hauled out of the hole for data retrieval, to telemetry systems for sending real-time or bulk data transmissions to the surface. The important issues for downhole recorders are storage media and capacity. For signal transmission systems, the issues are information modulation, data and error rate, and signal-to-noise ratio.IntroductionThis paper is an overview of the computer-based data acquisition and transmission techniques used in making pressure, temperature and flow measurements during well testing. Although there are many different types of commercially available systems from many different companies, the specifications and terminology tend to be aimed at specialists in electronics rather than reservoir engineers. Therefore, to make this a worthwhile overview to the SPE community, we focus on the key fundamentals that are common to all these systems and show field examples to help the reservoir engineer understand and apply this knowledge appropriately.Figure 1 shows the block diagram of a generalized data acquisition and transmission system. This, system must provide the computer with data that is a faithful representation of the measurements made downhole. In a well test, the sensors measure the desired parameter (e.g., pressure, temperature, flow rate, etc.) and convert the measured parameters into voltage, current or frequency signals. The acquisition block works exactly as its name implies: in it the measurement signals are acquired and converted into a form suitable for transmission to the surface or storage in a downhole recorder's memory. In the transmission block the acquired signals are encoded or modulated onto a transmission medium and delivered as computer input.Data AcquisitionIn a computer-based data acquisition system the analog signal from the sensor is converted into a digital signal by a process of sampling and analog-to-digital (A/D) conversion. There are several important considerations for this conversion, such as full-scale range, resolution and sampling rate. To illustrate these we first compare the decimal and digital representation of the same number. We are accustomed to using the decimal system where a whole number, p, is represented by its decimal coefficients. For example, the decimal number 253 really represents(1)In a digital system, 253 becomes the binary number: 11111101, where(2)Digital ResolutionA digital system's resolution is determined by the number of binary bits, n, for each measurement and the system's full-scale range (F.S.):(3)P. 695^ Keywords: field example 1, derivative, buildup, drillstem/well testing, noise, spe 24728, computer-based downhole data acquisition, drillstem testing, transmission, resolution Subjects: Formation Evaluation & Management, Drillstem/well testing This content is only available via PDF. 1992. Society of Petroleum Engineers You can access this article if you purchase or spend a download.