Abstract

In 1985 ARCO Oil and Gas Company developed an advanced data collection and analysis unit for real-time monitoring and analysis of hydraulic fracture stimulation treatments. This equipment is comprised of a truck containing a 40 channel data logger with two microprocessor computer systems, together with two flow skids and associated instrumentation. This paper gives examples of the application of this technology from over four years of use on over 300 treatments in a variety of oil and gas fields. Quality control problems are given which would not have been identified without the use of this system. These include problems with the addition of crosslinker, solid fluid loss additives, and poor fluid rheology. The need is shown for more detailed in-line quality control of fracture treatments than is routinely carried out by the industry.

References and illustrations at end of paper.

Introduction

Since the first intentional hydraulic stimulation in 19471 much has changed in the on-site monitoring of the fracturing process. There still exists the same objective, improved production. However, the economic success of the treatment often cannot be evaluated until several weeks or months of production have enabled clean up of the well and recovery of the injected fluid. By contrast, the operational success of the treatment is often measured on location by the ability to place all the designed fluid and proppant into the formation according to a predesigned schedule. The expense and complexity of present-day stimulation treatments has resulted in operators seeking new levels of technology for quantifying the process and the service delivered by the pumping company.

The initial evaluation of both the engineering design of the treatment and its implementation must be made from data obtained on-site at the time of the treatment. Such an evaluation allows for both a determination of the success of implementing the design from an operational standpoint, a determination of the formation's response, and any need for redesign prior to pumping the next treatment on a subsequent well. During the early 1980's the service companies made advances in monitoring stimulation treatments which included the use of microcomputers to gather digital data records and the matching of observed or calculated pressures.7–9 Stimulation monitoring centers were specifically developed for process monitoring and analysis of the stimulation treatment as it occurred. Frac monitors with digital displays were replaced by microprocessor controlled data loggers with graphical display of process variables. However, there was little change in the instrumentation routinely used to monitor a treatment. The process variables of surface treating pressure, clean gel rate, slurry rate and proppant concentration are the only variables routinely measured and recorded. In some cases, measurement of fluid properties has been attempted through the use of a variety of viscometers.6–8

In 1985, ARCO Oil and Gas Company realized the importance of developing a comprehensive quality control measurement and diagnostics system. This system (given the acronym "SMART" - Stimulation Monitoring Analysis and Research Truck) sought to provide a more complete and accurate representation of process variables during the fracturing operation.

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