1、Designation: E 1675 04e1Standard Practice forSampling Two-Phase Geothermal Fluid for Purposes ofChemical Analysis1This standard is issued under the fixed designation E 1675; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEEditorial changes were made throughout in June 2004.1. Scope1.1 The purpose of this practice is to obtain representative
3、samples of liquid and steam as they exist in a pipelinetransporting two-phase geothermal fluids.1.1.1 The liquid and steam samples are collected andproperly preserved for subsequent chemical analysis in thefield or an off-site analytical laboratory.1.1.2 The chemical composition data generated from
4、theanalysis of liquid and steam samples may be used for manyapplications important to geothermal energy exploration, de-velopment, and the long-term managed exploitation of geother-mal resources. These applications include, but are not limitedto, resource evaluations such as determining reservoir te
5、mpera-ture and the origin of reservoir fluids, compatibility of pro-duced fluids with production, power generation and reinjectionhardware exposed to the fluids (corrosivity and scale deposi-tion potential), long-term reservoir monitoring during fieldexploitation, and environmental impact evaluation
6、s includingemissions testing.1.1.2.1 To fully utilize the chemical composition data in theapplications stated in 1.1.2, specific physical data related to thetwo-phase discharge, wellbore, and geothermal reservoir maybe required. Mathematical reconstruction of the fluid chemistry(liquid and steam) to
7、 reservoir conditions is a primary require-ment in many applications.At a minimum, this requires preciseknowledge of the total fluid enthalpy and pressure or tempera-ture at the sample point. Fluid reconstruction and computationsto conditions different from the sample collection point arebeyond the
8、scope of this practice.1.2 This practice is limited to the collection of samples fromtwo-phase flow streams at pressures greater than 70 kPa gauge(10 psig) and having a volumetric vapor fraction of at least20 %. This practice is not applicable to single-phase flowstreams such as pumped liquid discha
9、rges at pressures abovethe flash point or superheated steam flows. Refer to Specifica-tion E 947 for sampling single-phase geothermal fluids.1.3 The sampling of geothermal fluid two-phase flowstreams (liquid and steam) requires specialized samplingequipment and proper orientation of sample ports wit
10、h respectto the two-phase flow line. This practice is applicable to wellsnot equipped with individual production separators.1.4 In many cases, these techniques are the only possibleway to obtain representative steam and liquid samples fromindividual producing geothermal wells. The sampling prob-lems
11、 that exist include the following:1.4.1 Unstable production flow rates that have a largedegree of surging,1.4.2 Unknown percentage of total flow that is flashed tosteam or is continuously flashing through the productionsystem,1.4.3 Mineral deposition during and after flashing of theproduced fluid in
12、 wellbores, production piping, and samplingtrains,1.4.4 Stratification of flow inside the pipeline and unusualflow regimes at the sampling ports, and1.4.5 Insufficient flash fraction to obtain a steam sample.1.5 This practice covers the sample locations, specializedsampling equipment, and procedures
13、 needed to obtain repre-sentative liquid and steam samples for chemical analysis.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and de
14、termine the applica-bility of regulatory limitations prior to use. For specific hazardstatements, see Section 7.2. Referenced Documents2.1 ASTM Standards:E 947 Specification for Sampling Single-Phase GeothermalLiquid or Steam for Purposes of Chemical Analysis22.2 Other Document:ASME Code Section VII
15、I, Division 1(1986), Pressure Ves-sel Design, Fabrication and Certification31This practice is under the jurisdiction of ASTM Committee E-44 on Solar,Geothermal, and OtherAlternative Energy Sources and is the direct responsibility ofSubcommittee E44.15 on Geothermal Field Development.Current edition
16、approved March 1, 2004. Published June 2004. Originallypublished as E 1675 95. Last previous edition E 1675 95.2Annual Book of ASTM Standards, Vol 12.02.3Available fromAmerican Society of Mechanical Engineers 345 E. 47th St. NewYork, NY 10017.1Copyright ASTM International, 100 Barr Harbor Drive, PO
17、Box C700, West Conshohocken, PA 19428-2959, United States.3. Summary of Practice3.1 Samples are collected from a pipeline carrying two-phase geothermal fluids by using a sampling separator thatseparates liquid and steam phases through centrifugal force. Afraction of the separated steam is condensed
18、and a fraction ofthe separated liquid is cooled. Portions of the condensed steamand cooled liquid are collected in appropriate sample contain-ers for subsequent chemical analysis.4. Significance and Use4.1 The objective of this practice is to obtain representativesamples of the steam and liquid phas
19、es as they exist in thepipeline at the sample point, without allowing steam conden-sation or additional liquid flashing in the separator. A signifi-cant feature of the practice is the use of a cyclone-typeseparator for high-efficiency phase separation which is oper-ated at flow rates high enough to
20、prevent significant heat losswhile maintaining an internal pressure essentially the same asthe pipeline pressure.4.2 Another significant feature of the practice is to locate thesampling separator at a point on the pipeline where thetwo-phase flow is at least partially stratified to aid in theseparat
21、ion process. It is neither necessary nor possible to passrepresentative proportions of each phase through the samplingseparator to obtain representative samples. The separator isusually attached to an appropriately oriented port to collecteach specific phasenormally on top of the line for steam anda
22、t the bottom for liquid. In some cases, piping configurationscan generate unusual flow regimes where the reverse isrequired. If the ratio of one phase to another is not extreme,representative samples of each phase can often be obtainedfrom a horizontal port on the side of the pipeline.4.3 This pract
23、ice is used whenever liquid or steam samples,or both, must be collected from a two-phase discharge forchemical analysis. This typically includes initial well-testingoperations when a well is discharged to the atmosphere orroutine well production when a well discharges to a fluidgathering system and
24、power plant. The combined two-phaseflow of several wells producing through a common gatheringsystem may also be sampled in accordance with this practice.4.4 This practice is not typically employed when individualwells produce to dedicated production separators. In thesecases, the separated steam and
25、 liquid at the outlet of theproduction separator is sampled in accordance with single-phase sampling methods (Specification E 947).5. Sample Location5.1 Sample locations vary and are dependent upon the grossquantities of each phase at the sample point. If sample ports areproperly oriented on the two
26、-phase pipeline, a certain degree ofphase stratification will have occurred prior to sampling,facilitating further separation of the target phase through thesampling separator.5.2 Ports are ideally located on the top and bottom of thepipeline at least eight diameters downstream and two diametersupst
27、ream of major flow disturbances such as pipe bends,reductions, valving, etc. (see Fig. 1).5.2.1 In cases where the fluid contains substantial quantitiesof solid debris that may plug the sample port, the liquid portcan be located at a 45 angle from the bottom, provided that asufficient liquid phase i
28、s present.5.2.2 If the flow regime is known, the number of ports maypossibly be reduced to a single port located either on the side,top, or bottom of the two-phase pipeline. Sufficient quantitiesof each phase must be available at the single port to allowcollection of representative steam and liquid
29、samples.5.2.3 The sample ports must be at least 1-in. diameter andconfigured with a full-open port ball or gate valve. Thisrequirement is necessary to ensure that only a minimal pressuredrop occurs through the port valve and associated piping. Scaleand debris often reduce the effective inner diamete
30、r of the port,therefore smaller ports are not recommended. The port sizerestriction also provides a safety margin given the weight of theseparator and force needed to install and remove fittings fromthe port.5.3 Sample ports should never be located on side-streampiping from the main flow line unless
31、 only the side-streamfluids are to be characterized. The proportions of each phaseare not likely to remain the same in a flow stream split off fromthe main flow line. Any pressure reduction in the side streampiping will change the steam and liquid compositions to anunknown degree.6. Equipment6.1 Sam
32、pling SeparatorA cyclone-type separator rated tothe pipeline pressure at the sample point, including a pressuregage, temperature probe, and sight glass (optional). Theseparator should be designed to attach directly to the sampleport to minimize heat loss and pressure drop.6.1.1 A typical sampling se
33、parator is shown in Fig. 2. Thisis a cyclone-type separator with a 1-in. pipe inlet attached at atangent to the separator body. The separator is rated to 3 500kPa gauge at 260C (500 psig at 500F). A pressure gage andthermocouple are located at the top of the separator, and steamand liquid sample val
34、ves are located at the bottom. Steam isdrawn from the top of the separator through an axial pipeextending up from the bottom of the vessel. Liquid is drawndirectly off the bottom. Internal baffles prevent liquid filmsfrom rising up the inner walls of the vessel with the steam flowto the sample valve
35、s. Vortex breakers are placed in the bottomof the vessel to prevent steam entrainment in the liquid flow tothe sample valves.6.1.1.1 The vent valve on the side of the sampling separator(No. 2 in Fig. 2) can be used to maintain an excess flow ofsteam and liquid through the separator, beyond the amoun
36、tneeded for sample collection. If sufficient quantities of eachphase are present, the side vent valve will maintain a liquidE167504e12level about 50 mm (2 in.) above the liquid sample valve (No.5inFig. 2). This allows collection of both steam and liquidsamples from the separator without the need to
37、adjust the liquidlevel.6.1.1.2 An optional sight-glass (PFA-fluorocarbon) for liq-uid level is located along one side of the separator to aid inproper separator operation and confirm the position of theliquid level. The sight glass is only rated to 1 700 kPa gauge(250 psig) and must be removed for h
38、igher pressure operation.6.2 Sample HosesSample hoses are PFA-lined stainlesssteel braided hoses rated to 500 psig and 450F. JIC typefittings or quick-disconnect fittings attach hoses to the separa-tor and condenser. Hoses are dedicated to either steam or liquidservice to prevent cross-contamination
39、. The inner diameter ofthe hose should not exceed 0.375 in. Stainless steel tubing mayalso be used (0.25 to 0.375-in. outside diameter), although it isless convenient. Convoluted, flexible stainless steel hose isspecifically excluded due to potential entrapment and contami-nation problems caused by
40、the internal convolutions.6.3 CondenserA sample condenser configuration withtwo sets of stainless steel tubing coils is recommended. One setof coils is dedicated for condensing steam and the other isdedicated for cooling liquid. The steam condenser coil has apressure/vacuum gage located at the sampl
41、e outlet and aregulating valve at the inlet. The steam flow can be preciselyregulated at the inlet as opposed to regulating the flow ofcondensate and gas at the outlet that can result in large pressuresurges and the hold-up of gas or condensate phases in the coils.The liquid cooling coil has a regul
42、ating valve at the outlet andan optional pressure gage. Regulating the outlet flow preventsflashing of liquid at the inlet to the condenser where chemicaldeposition could occur. Dedicated condensers with single setsof tubing coils for sampling either steam or liquid also can beused (see Fig. 3 and F
43、ig. 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 alsoincrease the risk of contamination and chemical depositionduring liquid sampling due to low fluid velocities and
44、longerresidence times within the tubing. In cases where the liquidcontains substantial quantities of particulate matter, 0.375-in.outside diameter tubing coils may be used to minimize coolingcoil plugging problems.6.3.2 In cases where the noncondensible gas concentrationin steam exceeds approximatel
45、y 5 % by weight, the outlet ofthe steam condenser coil should be at an elevation below theinlet with a continuous down-slope in the tubing from inlet tooutlet. This allows the small volume of condensate to freelydrain out of the condenser and prevents hold-up within thecoils.6.4 Condenser cooling ca
46、n be achieved by an ice/water bathsurrounding the coils or by a continuous overflow of coolingwater running into the vessel holding the coils (configurationshown in Fig. 3 and Fig. 4). Alternate configurations mayinclude a water-tight jacket around the coils through which aconstant source of cooling
47、 water flows. A source of coolantmay be a glycol/water mixture circulated through the con-denser jacket and an external fan-cooled heat exchanger.6.5 Pressure GageFor the measurement of separator pres-sure. Bourdon-tube type gages or pressure transducers may beused.Apressure-snubbing device is recom
48、mended to minimizethe pressure spikes and surges common in two-phase flowNOTE 1Minimum pipe diameters required upstream and downstream of major flow disturbances (piping bends, reductions).FIG. 1 Two-Phase Flowline Sampling Separator PortsE167504e13lines. The full-scale pressure range of the gage sh
49、ould notexceed two times the measurement reading. The gage shouldbe calibrated at monthly intervals when in routine use andevery six months for intermittent use. The measurementaccuracy of the gage should be at least 61 % of full-scale. Allgages require permanent identification numbers so that fielddata and calibration data can be traced to each specificinstrument.6.6 Temperature Meter and Thermocouple ProbesFor themeasurement of separator temperature. Temperature meters arethe digital readout style with plug-in thermocouple probes.Type K thermocouples are preferred due t
