WELL DRAWDOWN TEST SKIN
WELL DRAWDOWN TEST SOFTWARE

The following steps describe a typical design for a three-layer multirate test: 4 – Typical design for a three-layer multirate test (PL = production logging).

WELL DRAWDOWN TEST SKIN

2) is a straight line on the semilog plot, which in turn can be interpreted to yield the test objectives of the permeability and skin effect.įig. the 'sandface convolution time' (a time function akin to a generalized superposition function). The technique used here makes use of semilog analysis, in which rate-normalized pressures are plotted vs. A constant flow-rate function was sought to interpret this test. Clearly, the pressure and flow-rate data mirror each other, which is precisely the effect of the convolution.

1 shows an example in which the transient consists of a step-rate change from a high value with a downhole spinner flowmeter rotation rate of approximately 17 revolutions per second (rps) to a lower value with a flowmeter response of approximately 7 rps. The process can be made to converge rather rapidly for a pressure measurement of a given resolution, as long as the results allow for an acceptable margin of error.įig.

WELL DRAWDOWN TEST SOFTWARE

When software deconvolution operators are used, trial and error is required to convolve a flow-rate schedule with a pressure function that approximates the true constant rate-equivalent pressure function, thus reproducing the measured pressures. Where p D, the pressure function equivalent to a constant flow rate situation, is obtained by mathematical deconvolution of the pressure from the flow-rate fluctuations. The bottomhole pressure and flow rate are mathematically convolved (coupled) as follows: The pressure-flow convolution involves simultaneous bottomhole flow rate and pressure measurements to correct for the variations of bottomhole pressure caused by flow rate fluctuations during drawdown tests. Pressure flow convolution and deconvolution

Determine hydraulic communication between wells.

Evaluate workover or stimulation treatments.ĭescriptive reservoir tests are conducted to:.

Obtain representative fluid samples suitable for PVT analysis.

Measure reservoir pressure and temperature.

Identify produced fluids and determine their respective volume ratios.

Characterize formation damage and other sources of skin effect.

8.3 Vertical extent of fracturing and detecting lost circulation.

8.1 Recommendations for temperature profiling.

8 Temperature profiles in production and injection wells.

7 Using pressure to characterize reservoir fluids.

5.2 Packer and multiple-probe tests for vertical interference testing.

5.1 Packer probe tests: small-scale drillstem testing.

2 Pressure flow convolution and deconvolution.

1 Applications of pressure transient tests.

Well drawdown test