Chapter%207 - Petrophysics MSc Course Notes Fluid Testing...

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Petrophysics MSc Course Notes Fluid Testing and Pressure Logs Dr. Paul Glover Page 74 7. FLUID TESTING AND PRESSURE LOGS 7.1 Introduction Formation fluid testing involves taking fluid samples from the formation and measuring their pressures. It gives information on the types and properties of fluids in the formation, indicates the presence of hydrocarbons, and provides information on the pressures of the fluids within the formation. There are three generic types of test, the second of which will be examined in detail as it is a wireline method. The three measurement types are as follows, and are described in the order that they are performed, in their complexity, and therefore their cost. Drillstem testing. This is carried out during the drilling of the well. A portion of perforated drill pipe and one or two devices for sealing the interval of the well of interest off ( packers ) are lowered down the well to the required depth. The packer is then expanded to make a seal between the borehole wall and the drill pipe. If the bottom of the well is being tested, only one packer is needed. If an interval further up the well is being tested, two packers are needed, one above the interval and one below. A valve is then opened to reduce the pressure within the drill stem and the packed-off interval to surface pressures. Fluids will flow from the formation into the packed- off interval and hence to the surface through the perforations in the drill pipe and up the pipe. These fluids may be sampled and analyzed. Note that this procedure is the equivalent of a temporary completion of the well. (Fig. 7.1). Figure 7.1 The drillstem test. Wireline formation testing ( RFT ). This operation is carried out in an open hole during wireline logging operations. The wireline tool is lowered down the uncased hole to the point of interest. It is then jacked and sealed against the borehole wall. Samples of fluids and measurements of the fluid pressures are then taken. Note that this form of logging is not continuous, and is carried out at a few previously defined depths in the reservoir zone of the well only (Fig. 7.2). Figure 7.2 The RFT test. Formation Drillstem Perforated Interval Borehole Inflated Packer Formation RFT Tool Sampler & Pressure Measurement Borehole Jacking Arm
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Petrophysics MSc Course Notes Fluid Testing and Pressure Logs Dr. Paul Glover Page 75 Production Testing. This is carried out in a cased hole and completed hole with a packer that has been set in place and a production pipe. The casing is perforated using a wireline perforation gun. As the pressure inside the production pipe is held at a value that is lower than the formation pressure, the formation will produce fluids, which by this stage in the well completion, should be hydrocarbons. If the test produces sufficient hydrocarbons, the production may be allowed to continue as a fully completed well (Fig. 7.3).
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This note was uploaded on 10/30/2011 for the course PETROLEUM Short cour taught by Professor Dr.paulglover during the Winter '11 term at University of Aberdeen.

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Chapter%207 - Petrophysics MSc Course Notes Fluid Testing...

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