ASTM E1675-04(2012)
(Practice)Standard Practice for Sampling Two-Phase Geothermal Fluid for Purposes of Chemical Analysis
Standard Practice for Sampling Two-Phase Geothermal Fluid for Purposes of Chemical Analysis
SIGNIFICANCE AND USE
4.1 The objective of this practice is to obtain representative samples of the steam and liquid phases as they exist in the pipeline at the sample point, without allowing steam condensation or additional liquid flashing in the separator. A significant feature of the practice is the use of a cyclone-type separator for high-efficiency phase separation which is operated at flow rates high enough to prevent significant heat loss while maintaining an internal pressure essentially the same as the pipeline pressure.
4.2 Another significant feature of the practice is to locate the sampling separator at a point on the pipeline where the two-phase flow is at least partially stratified to aid in the separation process. It is neither necessary nor possible to pass representative proportions of each phase through the sampling separator to obtain representative samples. The separator is usually attached to an appropriately oriented port to collect each specific phase—normally on top of the line for steam and at the bottom for liquid. In some cases, piping configurations can generate unusual flow regimes where the reverse is required. If the ratio of one phase to another is not extreme, representative samples of each phase can often be obtained from a horizontal port on the side of the pipeline.
4.3 This practice is used whenever liquid or steam samples, or both, must be collected from a two-phase discharge for chemical analysis. This typically includes initial well-testing operations when a well is discharged to the atmosphere or routine well production when a well discharges to a fluid gathering system and power plant. The combined two-phase flow of several wells producing through a common gathering system may also be sampled in accordance with this practice.
4.4 This practice is not typically employed when individual wells produce to dedicated production separators. In these cases, the separated steam and liquid at the outlet of the production separator is sampled in ac...
SCOPE
1.1 The purpose of this practice is to obtain representative samples of liquid and steam as they exist in a pipeline transporting two-phase geothermal fluids.
1.1.1 The liquid and steam samples are collected and properly preserved for subsequent chemical analysis in the field or an off-site analytical laboratory.
1.1.2 The chemical composition data generated from the analysis of liquid and steam samples may be used for many applications important to geothermal energy exploration, development, and the long-term managed exploitation of geothermal resources. These applications include, but are not limited to, resource evaluations such as determining reservoir temperature and the origin of reservoir fluids, compatibility of produced fluids with production, power generation and reinjection hardware exposed to the fluids (corrosivity and scale deposition potential), long-term reservoir monitoring during field exploitation, and environmental impact evaluations including emissions testing.
1.1.2.1 To fully utilize the chemical composition data in the applications stated in 1.1.2, specific physical data related to the two-phase discharge, wellbore, and geothermal reservoir may be required. Mathematical reconstruction of the fluid chemistry (liquid and steam) to reservoir conditions is a primary requirement in many applications. At a minimum, this requires precise knowledge of the total fluid enthalpy and pressure or temperature at the sample point. Fluid reconstruction and computations to conditions different from the sample collection point are beyond the scope of this practice.
1.2 This practice is limited to the collection of samples from two-phase flow streams at pressures greater than 70 kPa gauge (10 psig) and having a volumetric vapor fraction of at least 20 %. This practice is not applicable to single-phase flow streams such as pumped liquid discharges at pressures above the flash point or superheated steam flo...
General Information
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: E1675 − 04 (Reapproved 2012)
Standard Practice for
Sampling Two-Phase Geothermal Fluid for Purposes of
Chemical Analysis
This standard is issued under the fixed designation E1675; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.3 The sampling of geothermal fluid two-phase flow
streams (liquid and steam) requires specialized sampling
1.1 The purpose of this practice is to obtain representative
equipment and proper orientation of sample ports with respect
samples of liquid and steam as they exist in a pipeline
to the two-phase flow line. This practice is applicable to wells
transporting two-phase geothermal fluids.
not equipped with individual production separators.
1.1.1 The liquid and steam samples are collected and
properly preserved for subsequent chemical analysis in the 1.4 In many cases, these techniques are the only possible
field or an off-site analytical laboratory. way to obtain representative steam and liquid samples from
1.1.2 The chemical composition data generated from the individual producing geothermal wells. The sampling prob-
analysis of liquid and steam samples may be used for many lems that exist include the following:
applications important to geothermal energy exploration, 1.4.1 Unstable production flow rates that have a large
development, and the long-term managed exploitation of degree of surging,
geothermal resources. These applications include, but are not 1.4.2 Unknown percentage of total flow that is flashed to
limited to, resource evaluations such as determining reservoir steam or is continuously flashing through the production
temperature and the origin of reservoir fluids, compatibility of system,
produced fluids with production, power generation and rein- 1.4.3 Mineral deposition during and after flashing of the
jection hardware exposed to the fluids (corrosivity and scale produced fluid in wellbores, production piping, and sampling
deposition potential), long-term reservoir monitoring during trains,
field exploitation, and environmental impact evaluations in- 1.4.4 Stratification of flow inside the pipeline and unusual
cluding emissions testing. flow regimes at the sampling ports, and
1.1.2.1 To fully utilize the chemical composition data in the 1.4.5 Insufficient flash fraction to obtain a steam sample.
1.1.2, specific physical data related to the
applications stated in
1.5 This practice covers the sample locations, specialized
two-phase discharge, wellbore, and geothermal reservoir may
sampling equipment, and procedures needed to obtain repre-
berequired.Mathematicalreconstructionofthefluidchemistry
sentative liquid and steam samples for chemical analysis.
(liquid and steam) to reservoir conditions is a primary require-
1.6 This standard does not purport to address all of the
mentinmanyapplications.Ataminimum,thisrequiresprecise
safety concerns, if any, associated with its use. It is the
knowledge of the total fluid enthalpy and pressure or tempera-
responsibility of the user of this standard to establish appro-
ture at the sample point. Fluid reconstruction and computations
priate safety and health practices and determine the applica-
to conditions different from the sample collection point are
bility of regulatory limitations prior to use. For specific hazard
beyond the scope of this practice.
statements, see Section 7.
1.2 Thispracticeislimitedtothecollectionofsamplesfrom
two-phase flow streams at pressures greater than 70 kPa gauge
2. Referenced Documents
(10 psig) and having a volumetric vapor fraction of at least
2.1 ASTM Standards:
20 %. This practice is not applicable to single-phase flow
E947 Specification for Sampling Single-Phase Geothermal
streams such as pumped liquid discharges at pressures above
Liquid or Steam for Purposes of Chemical Analysis
the flash point or superheated steam flows. Refer to Specifica-
2.2 Other Document:
tion E947 for sampling single-phase geothermal fluids.
ASMECodeSectionVIII,Division1(1986), PressureVessel
Design, Fabrication and Certification
This practice is under the jurisdiction of ASTM Committee E44 on Solar,
Geothermal and OtherAlternative Energy Sources and is the direct responsibility of
SubcommitteeE44.15onGeothermalFieldDevelopment,UtilizationandMaterials.
Current edition approved Dec. 1, 2012. Published December 2012. Originally Annual Book of ASTM Standards, Vol 12.02.
ε1 3
approved in 1995. Last previous edition approved in 2004 as E1675 – 04 . DOI: AvailablefromAmericanSocietyofMechanicalEngineers345E.47thSt.New
10.1520/E1675-04R12. York, NY 10017.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1675 − 04 (2012)
3. Summary of Practice representative samples of each phase can often be obtained
from a horizontal port on the side of the pipeline.
3.1 Samples are collected from a pipeline carrying two-
phase geothermal fluids by using a sampling separator that
4.3 This practice is used whenever liquid or steam samples,
separates liquid and steam phases through centrifugal force. A
or both, must be collected from a two-phase discharge for
fraction of the separated steam is condensed and a fraction of
chemical analysis. This typically includes initial well-testing
the separated liquid is cooled. Portions of the condensed steam
operations when a well is discharged to the atmosphere or
and cooled liquid are collected in appropriate sample contain-
routine well production when a well discharges to a fluid
ers for subsequent chemical analysis.
gathering system and power plant. The combined two-phase
flow of several wells producing through a common gathering
4. Significance and Use
system may also be sampled in accordance with this practice.
4.1 The objective of this practice is to obtain representative
4.4 This practice is not typically employed when individual
samples of the steam and liquid phases as they exist in the
wells produce to dedicated production separators. In these
pipeline at the sample point, without allowing steam conden-
cases, the separated steam and liquid at the outlet of the
sation or additional liquid flashing in the separator. A signifi-
production separator is sampled in accordance with single-
cant feature of the practice is the use of a cyclone-type
phase sampling methods (Specification E947).
separator for high-efficiency phase separation which is oper-
ated at flow rates high enough to prevent significant heat loss
5. Sample Location
while maintaining an internal pressure essentially the same as
5.1 Sample locations vary and are dependent upon the gross
the pipeline pressure.
quantitiesofeachphaseatthesamplepoint.Ifsampleportsare
4.2 Anothersignificantfeatureofthepracticeistolocatethe
properlyorientedonthetwo-phasepipeline,acertaindegreeof
sampling separator at a point on the pipeline where the
phase stratification will have occurred prior to sampling,
two-phase flow is at least partially stratified to aid in the
facilitating further separation of the target phase through the
separation process. It is neither necessary nor possible to pass
sampling separator.
representative proportions of each phase through the sampling
5.2 Ports are ideally located on the top and bottom of the
separator to obtain representative samples. The separator is
pipelineatleasteightdiametersdownstreamandtwodiameters
usually attached to an appropriately oriented port to collect
upstream of major flow disturbances such as pipe bends,
each specific phase—normally on top of the line for steam and
reductions, valving, etc. (see Fig. 1).
at the bottom for liquid. In some cases, piping configurations
can generate unusual flow regimes where the reverse is 5.2.1 In cases where the fluid contains substantial quantities
required. If the ratio of one phase to another is not extreme, of solid debris that may plug the sample port, the liquid port
NOTE 1—Minimum pipe diameters required upstream and downstream of major flow disturbances (piping bends, reductions).
FIG. 1 Two-Phase Flowline Sampling Separator Ports
E1675 − 04 (2012)
can be located at a 45° angle from the bottom, provided that a
sufficient liquid phase is present.
5.2.2 If the flow regime is known, the number of ports may
possibly be reduced to a single port located either on the side,
top, or bottom of the two-phase pipeline. Sufficient quantities
of each phase must be available at the single port to allow
collection of representative steam and liquid samples.
5.2.3 The sample ports must be at least 1-in. diameter and
configured with a full-open port ball or gate valve. This
requirementisnecessarytoensurethatonlyaminimalpressure
dropoccursthroughtheportvalveandassociatedpiping.Scale
and debris often reduce the effective inner diameter of the port,
therefore smaller ports are not recommended. The port size
restrictionalsoprovidesasafetymargingiventheweightofthe
separator and force needed to install and remove fittings from
the port.
5.3 Sample ports should never be located on side-stream
piping from the main flow line unless only the side-stream
fluids are to be characterized. The proportions of each phase
are not likely to remain the same in a flow stream split off from
the main flow line. Any pressure reduction in the side stream
piping will change the steam and liquid compositions to an
unknown degree.
6. Equipment
6.1 Sampling Separator—A cyclone-type separator rated to
the pipeline pressure at the sample point, including a pressure
gage, temperature probe, and sight glass (optional). The
separator should be designed to attach directly to the sample
port to minimize heat loss and pressure drop. 1) 1 in. Two-Phase Inlet (Hammer Union)
2) ⁄2 in. Vent Valve (Regulating Valve or Ball Valve)
6.1.1 A typical sampling separator is shown in Fig. 2. This
3) ⁄4 in. Steam Sample Valve (Regulating Valve)
is a cyclone-type separator with a 1-in. pipe inlet attached at a 1
4) ⁄2 in. Steam Bleed Valve (Regulating Valve)
1 3
5) ⁄4 in. or ⁄8 in. Liquid Sample Valve (Ball Valve)
tangent to the separator body. The separator is rated to 3 500
3 1
6) ⁄8 in. Teflon Sight Glass (250 psi limit: ⁄16 in. wall, Teflon PFA)
kPa gauge at 260°C (500 psig at 500°F). A pressure gage and
7) ⁄4 in. × 12 in. Type K Thermocouple
thermocouple are located at the top of the separator, and steam
8) Pressure Gage with Surge Protector Valve
9) ⁄2 in. × Steam Outlet Pipe
and liquid sample valves are located at the bottom. Steam is
10) Baffle Ring
drawn from the top of the separator through an axial pipe
11) Vortex Breaker Plates
extending up from the bottom of the vessel. Liquid is drawn
12) Separator Body, 4 in. I.D. × 12 in.
Material specification: All metal components 304 or 316 stainless steel
directly off the bottom. Internal baffles prevent liquid films
FIG. 2 Sampling Separator
from rising up the inner walls of the vessel with the steam flow
to the sample valves. Vortex breakers are placed in the bottom
of the vessel to prevent steam entrainment in the liquid flow to 6.2 Sample Hoses—Sample hoses are PFA-lined stainless
steel braided hoses rated to 500 psig and 450°F. JIC type
the sample valves.
fittings or quick-disconnect fittings attach hoses to the separa-
6.1.1.1 The vent valve on the side of the sampling separator
torandcondenser.Hosesarededicatedtoeithersteamorliquid
(No. 2 in Fig. 2) can be used to maintain an excess flow of
service to prevent cross-contamination. The inner diameter of
steam and liquid through the separator, beyond the amount
the hose should not exceed 0.375 in. Stainless steel tubing may
needed for sample collection. If sufficient quantities of each
also be used (0.25 to 0.375-in. outside diameter), although it is
phase are present, the side vent valve will maintain a liquid
less convenient. Convoluted, flexible stainless steel hose is
level about 50 mm (2 in.) above the liquid sample valve (No.
specifically excluded due to potential entrapment and contami-
5in Fig. 2). This allows collection of both steam and liquid
nation problems caused by the internal convolutions.
samplesfromtheseparatorwithouttheneedtoadjusttheliquid
level.
6.3 Condenser—Asamplecondenserconfigurationwithtwo
6.1.1.2 An optional sight-glass (PFA-fluorocarbon) for liq- sets of stainless steel tubing coils is recommended. One set of
uid level is located along one side of the separator to aid in coils is dedicated for condensing steam and the other is
proper separator operation and confirm the position of the dedicated for cooling liquid. The steam condenser coil has a
liquid level. The sight glass is only rated to 1 700 kPa gauge pressure/vacuum gage located at the sample outlet and a
(250 psig) and must be removed for higher pressure operation. regulating valve at the inlet. The steam flow can be precisely
E1675 − 04 (2012)
regulated at the inlet as opposed to regulating the flow of
condensateandgasattheoutletthatcanresultinlargepressure
surges and the hold-up of gas or condensate phases in the coils.
The liquid cooling coil has a regulating valve at the outlet and
an optional pressure gage. Regulating the outlet flow prevents
flashing of liquid at the inlet to the condenser where chemical
deposition could occur. Dedicated condensers with single sets
of tubing coils for sampling either steam or liquid also can be
used (see Fig. 3 and Fig. 4).
6.3.1 The condenser coil tubing must not exceed 0.25-in.
outside diameter to prevent the segregation of gas and conden-
sate phases during sampling of steam. Larger tubing sizes also
increase the risk of contamination and chemical deposition
during liquid sampling due to low fluid velocities and longer
residence times within the tubing. In cases where the liquid
contains substantial quantities of particulate matter, 0.375-in.
outside diameter tubing coils may be used to minimize cooling
coil plugging problems.
6.3.2 In cases where the noncondensible gas concentration
1) JIC Fitting ( ⁄4 in. NPT × S.A.E. 37°)
in steam exceeds approximately 5 % by weight, the outlet of 1
2) Pipe Elbow ( ⁄4 in. NPT)
1 1 3
3) Bulkhead Fitting ( ⁄4 in. NPT × ⁄4 in. or ⁄8 in. Swagelok)
the steam condenser coil should be at an elevation below the
1 3
4) 20 ft. × ⁄4 in. or ⁄8 in. O.D. Stainless Steel Tubing (0.035 in. wall)
inlet with a continuous down-slope in the tubing from inlet to
5) Pipe Nipple (3 in. × ⁄4 in. NPT)
outlet. This allows the small volume of condensate to freely
6) Sample Valve (Ball Valve, ⁄4 in. NPT)
1 1
7) Hose Adapter ( ⁄4 in. NPT × ⁄4 in. Hosebarb)
drain
...
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