TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn the past, in order to acquire real time, bottomhole SRO (surface read-out) data, either a downhole latching system or a download probe in close proximity to the transmitting device had to be used. An innovative SRO system that takes advantage of state-of-the-art developments in acoustic technologies, wireline, and wireless transmission, and yet, is compatible with tools conventionally used during drill stem test operations has now been introduced to the industry. This acoustic data-acquisition system provides access to real-time bottomhole data using either a wireline-deployed probe or via wireless acoustic signals sent through the production tubing. If the probe is used, this does not have to be close to the transmitting device in order to transfer the data to surface. Since the system offers the option of transmitting via wireline or via the wall of the testing pipe, the need for a probe or latching device along with the inherent problems that sometimes occur because the probe becomes stuck in the latch or mechanically fails can be eliminated. Finally, the additional rig time required for preparation and running of the probe to move the Acoustic Telemetry System (ATS) transmitter up to proper depth is saved, reducing operational costs. BackgroundEarly SRO systems required a mechanical downhole latch mechanism that required wireline in the hole for communication of the information from the downhole probe to the surface. For low-rate, low-pressure wells without any H2S or CO2, use of this type of system posed few potential problems. However, as the industry pursued testing of deeper, higher-capacity wells with greater concentrations of impurities in the well effluent, several safety issues were experienced with the use of wireline in the hole. In the late 1980's and early 1990's, various intermediate SRO systems used electromagnetic proximity probes to alleviate some of the safety issues and to improve the operational reliability of the SRO systems. However, these systems did not address the fundamental problem of using wireline-deployed signal pick-up probes. The realization of the advantages that a reliable wireless method of communicating downhole data to surface could provide is not new, and the oil industry began searching for a wireless method of communicating downhole data to the surface over 50 years ago. One of the first documented field tests was performed in 1948 to study the response at the surface of a downhole hammer. The results were not encouraging, and the project was dropped. As technology evolved, interest in wireless telemetry rekindled. Several companies revisited acoustic telemetry and developed research projects to address transmission of acoustic signals through tubing. Significant work by Barnes and Kirkwood in 1972 1 and, by Douglas Drumheller in 1988 2,3 helped the industry to understand how the acoustic waves responded to the tubing at various frequencies. Based on the principles laid by the earlier work, several companies now offe...
In the oilfield, high pressure/high temperature wells (HP/HT) are those with more than 10,000 psi bottomhole pressure and bottomhole temperatures in excess of 300° F. As such, the severe reservoir environment in these wells requires special testing equipment that can sustain the high pressures and temperatures. Special testing processes and equipment have been designed to reduce the risks in achieving successful evaluations, and HP/HT wells can be successfully tested under both rig-supported and rigless operations and in both cased- and openhole conditions. This paper will compare some of the testing experiences in HP/HT wells tested several years ago, and some that are more recent and have used new technologies to increase the success in obtaining the information needed for the evaluations. With the new technology, it has been possible to transmit the data collected during the evaluation to offsite locations using internet capabilities, collect more accurate data using memory gauge systems capable of working at high temperatures, gather downhole real time data using various collection tools, improve well productivity by applying propellant technologies, and improve perforating performance by using state-of-the-art charges. The paper will describe the downhole tool system used to perform the well testing evaluation under severe well conditions. Also discussed will be how it was capable of acquiring well data in real time, and then, disseminating it over the Internet to allow collaboration with a larger number of individuals. This allowed immediate decisions concerning operational or program changes to be made and implemented at the wellsite. The system has been successfully deployed on a number of well tests in Australia and Venezuela, and the paper will present some of these case histories as illustrations of the well testing capabilities now possible in varying conditions. Introduction Well Testing The exploratory and appraisal phases in exploration wells and during the development stage of certain fields requires the application of different well testing techniques that allow determination of whether a formation is capable of flowing and also permit the collection or sampling of fluids produced during the well-testing period. In general, the well testing procedure is a dynamic process that must be capable of providing information about the reservoir permeability, formation damage, bottomhole pressure and temperature, and the formation's productivity index. By applying pressure-transient tests, the well developer can obtain an analysis and characterization of the tested formation. To achieve the objectives of the well testing operation, different tools and equipment are required both downhole and at surface. For example, a temporary completion must be in place in order to isolate the formation to be tested. In addition, in most cases, the use of downhole tester valves to shut-in the well downhole is required. The well testing procedure can be performed under two different scenarios, and depending on the one chosen, will require different tools to achieve the test objectives. The two scenarios are rig and rigless operations. Rigless operations require the use of memory gauges, surface read-out capabilities, production logging tools, surface well testing equipment (sometimes referred to as coiled-tubing/perforating operations), and data-acquisition facilities. Finally, surface testing equipment, which includes separators, gauge tanks, storage tanks, transfer pumps and data transmission capabilities, are required at surface to comply with well-control requirements and data collection necessities.
TX 75083-3836 U.S.A., fax 01-972-952-9435.Abstract PDVSA operates the RG-231 and AM-102 wells, located in eastern Venezuela. The wells are characterized by stratified reservoirs and complex geology due to the presence of low permeability and porosity. The RG-231 well is in a gas reservoir with extremely low permeability (less than 0.02 md). During a well-testing operation, additional perforations were added to increase gas production. The AM-102 well was in an oil reservoir.To effectively meet the operator's needs for a method that would help to optimize well productivity and costs without compromising the results of the operation, a change from traditional perforating operations was required. A propellantassisted perforating method to optimize well productivity while maintaining stringent health, safety and environmental standards was proposed. The propellant-assisted perforating method uses standard perforating components and procedures; thus, it was capable of providing the necessary safety features. The propellant is essentially an oxidizer that creates carbon dioxide gas at extremely high peak pressures in the millisecond time regime to overcome in-situ stresses and create perforation breakdown and mild fracturing near the wellbore. This paper will focus on the method developed to satisfy the operational challenges specific to the PDVSA wells. The discussion will cover the results obtained by using propellant technology in a low-permeability, low-porosity reservoir as well as how the technique was capable of addressing the operator's requirements in data acquisition as well as the difficult reservoir conditions. Instrumental in the success of the methodology was the combined use of super-deep penetration technology and propellant assisted perforation.
In the past, in order to carry out any type of real time analysis or control during a welltest, the subject matter expert had to be present at the wellsite. This paper will describe a recently developed real time operations (RTO) data acquisition and management system that uses advances in software operating systems, networking, telecommunications and Internet/intranet access to allow users to have access to real time data and information regardless of their locations. This type of real time access to well information allows expertise to be available that might not have been in the past due to distance constraints, and time and expense required to travel to the wellsite. It also allows real time collaboration from all individuals who have access to the data, regardless of their location, so that reservoir management decisions can be made quickly and more efficiently. The system has been successfully deployed on a number of welltests in the deepwater Gulf of Mexico, offshore Egypt and onshore eastern Venezuela. An overview of the operations, which includes efficiency gains and time saved, will illustrate how controlled access to real time data and information via a local area network (LAN), a wide area network (WAN), an intranet, or the Internet can positively affect cost and efficiency by allowing state-of-the-art testing to be performed in remote areas where it previously might not have been possible or economically feasible using traditional testing systems. Introduction For many years, reservoir testing has been considered an integral part of field development, and the industry has continued to review testing methods that can improve economics and efficiency.1,2 Real time access to welltest data is not a new concept.3,4 The oil industry has been practicing real time data acquisition at the wellsite for a number of years. Collection of data such as pressures, temperatures, flowrates, fluid properties, etc., at the surface as well as downhole is relatively common, especially during an exploration type of welltest. Over the years, occasional attempts have been made to transmit data back to an office in real time using modems and voice lines or other existing data communications means; however, the frequency of jobs with remote data transmission has been minimal. The RTO system described in this paper has been in use in the welltesting environment for over a year, and the system has greatly enhanced decision making because of its capability of making real time data and information available to all personnel, regardless of their location. Anyone at the wellsite, at the office, at home or anywhere else that offers an Internet connection can have access simultaneously to the same real time data and information.5,6 This provides a powerful collaboration and decision making tool that was not readily available in the past. By applying the Internet's competencies, the collaboration capability goes far beyond the constraints of proprietary WAN access. This means that secure, controlled access to the data and information can easily be administered to multiple individuals, whether they work directly for the operator, a partner, a service company, a consultant, etc. System Overview Integration of three key technologies can be viewed as core to a system offering real time access to welltest data. These core needs are:System architecture to allow data flow from wellsite to Internet browserCommunications infrastructure to extend the network to the wellsiteData presentation and delivery. A graphic depicting the relationship of these technologies can be seen in Fig. 1 in which data flow is displayed very simply as a whole unit.
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