Keywords: borehole drilling, discontinuities, fault zones, field testing flow and flow rate, ground water, permeability, pressure testing, pulse testing, rock, saturation, storativity, transmissivity, viscosity, water, water saturation,, ICS Number Code 07.040 (Astronomy. Geodesy. Geography), 93.020 (Earthworks. Excavations. Foundation construction. Underground works)
Doplňujúce informácie
Significance and Use
5.1Test
Method—The pulse test method is used to determine the
transmissivity and storativity of low-permeability formations
surrounding the packed-off intervals. This test method is
considerably shorter in duration than the pumping and slug tests
used in more permeable rocks. To obtain results to the desired
accuracy, pumping and slug tests in low-permeability formations are
too time consuming, as indicated in Fig. 1 (from Bredehoeft and Papadopulos
5.2transmissivity, T—the transmissivity of a
formation of thickness, b, is defined as follows:
The efhc is the hydraulic conductivity of
a material if it were homogeneous and porous over the entire
interval. The hydraulic conductivity, K, is related to the equivalent
formation, 5.3storativity, S—the storativity (or
storage coefficient) of a formation of thickness, b, is defined as follows:
5.4Analysis—The transient pressure data
obtained using the suggested method are evaluated by the
curve-matching technique described by Bredehoeft and Papadopulos
5.5Units:
5.5.1Conversions—The permeability of a
formation is often expressed in terms of the unit darcy. A porous
medium has a permeability of 1 darcy when a fluid of viscosity 1 cP
(1 mPa·s) flows through it at a rate of 1 cm3/s
(10−6 m3/s)/1 cm2 (10−4
m2) cross-sectional area at a pressure differential of 1
atm (101.4 kPa)/1 cm (10 mm) of length. One darcy corresponds to
0.987 μm2. For water as the flowing fluid at 20°C, a
hydraulic conductivity of 9.66 μm/s corresponds to a permeability
of 1 darcy.
Note 1:A darcy (or darcy unit) and millidarcy (md or mD) are
units of permeability. They are not SI units, but are widely used
in petroleum engineering and geology. A darcy has dimensional units
in length.
5.5.2Viscosity of Water—Table 1 shows the viscosity of water as a
function of temperature.
Note 2:The quality of the result produced by this standard is
dependent on the competence of the personnel performing it and the
suitability of the equipment and facility used. Agencies that meet
the criteria of Practice D3740 are generally considered capable of
competent and objective testing/sampling/observation/ and the like.
Users of this standard are cautioned that compliance with Practice
D3740 does not itself
guarantee reliable results. Reliable results depend on many
factors; D3740 provides a
means of evaluating some of those factors.
Note 3:The function of wells in any unconfined setting in a
fractured terrain might make the determination of k problematic
because the wells might only intersect tributary or subsidiary
channels or conduits. The problems determining the k of a channel
or conduit notwithstanding, the partial penetration of tributary
channels may make determination of a meaningful number difficult.
If plots of k in carbonates and other fractured settings are made
and compared, they may show no indication that there are conduits
or channels present, except when with the lowest probability one
maybe intersected by a borehole and can be verified, such problems
are described by Worthington 1.1 This test method covers a field
procedure for determining the transmissivity and storativity of
geological formations having permeabilities lower than
10−3 μm2 (1 millidarcy) using the pressure
pulse technique.
1.2 The transmissivity and storativity
values determined by this test method provide a good approximation
of the capacity of the zone of interest to transmit water, if the
test intervals are representative of the entire zone and the
surrounding rock is fully water saturated.
1.3Units—The values stated in SI units are
to be regarded as the standard. The values in parentheses are
mathematical conversions provided for information only and are not
considered standard. Reporting of test results in units other than
SI shall not be regarded as nonconformance with this standard.
1.4 All observed and calculated values
shall conform to the guidelines for significant digits and rounding
established in Practice D6026, unless superseded by this
standard.
1.4.1 For purposes of comparing a
measured or calculated value(s) with specified limits, the measured
or calculated value(s) shall be rounded to the nearest decimal or
significant digits in the specified limits.
1.4.2 The procedures used to specify how
data are collected/recorded or calculated in this standard are
regarded as the industry standard. In addition, they are
representative of the significant digits that generally should be
retained. The procedures used do not consider material variation,
purpose for obtaining the data, special purpose studies, or any
considerations for the user’s objectives; and it is common practice
to increase or reduce significant digits of reported data to be
commensurate with these conditions. It is beyond the scope of this
standard to consider significant digits used in analysis methods
for engineering design.
1.5This standard does not purport to
address all of the safety concerns, if any, associated with its
use. It is the responsibility of the user of this standard to
establish appropriate safety, health, and environmental practices
and determine the applicability of regulatory limitations prior to
use.
1.6This international standard was
developed in accordance with internationally recognized principles
on standardization established in the Decision on Principles for
the Development of International Standards, Guides and
Recommendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
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