1、Recommended Practice for Field Analysis of Crude Oil Samples Containing from Two to Fifty Percent Water by Volume API RECOMMENDED PRACTICE 87 FIRST EDITION, AUGUST 2007 EFFECTIVE DATE: FEBRUARY 1, 2008 REAFFIRMED, SEPTEMBER 2012Foreword This Recommended Practice is under the jurisdiction of the API
2、Executive Committee on Drilling and Production Operations. Nothing contained in any API publication is to be construed as granting any right, by implication or otherwise, for the manufacture, sale, or use of any method, apparatus, or product covered by letters patent. Neither should anything contain
3、ed in the publication be construed as insuring anyone against liability for infringement of letters patent. This document was produced under API standardization procedures that ensure appropriate notification and participation in the developmental process and is designated as an API standard. Questi
4、ons concerning the interpretation of the content of this publication or comments and questions concerning the procedures under which this publication was developed should be directed in writing to the Director of Standards, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005. R
5、equests for permission to reproduce or translate all or any part of the material published herein should also be addressed to the director. Generally, API standards are reviewed and revised, reaffirmed, or withdrawn at least every five years. A one-time extension of up to two years may be added to t
6、his review cycle. Status of the publication can be ascertained from the API Standards Department, telephone (202) 682-8000. A catalog of API publications and materials is published annually and updated quarterly by API, 1220 L Street, N.W., Washington, D.C. 20005. Suggested revisions are invited and
7、 should be submitted to the Standards Department, API, 1220 L Street, NW, Washington, D.C. 20005, standardsapi.org. iiiContents Page Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8、 . . . . vi 1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9、 . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.1 Normative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.2 Informative . . . . . . . . . . . . . . . . . . . . . . . . . . .
10、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 Terms and Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 4 Symbols and Abbreviated Terms
11、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 4.1 Symbols and Nomenclature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 4.2 Abbreviated Terms
12、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 5 Sampling and Stream Mixing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13、3 5.1 Automatic Sampler and Stream Mixing Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 5.2 Sample Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14、5 6 Sample Handling and Mixing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6.1 Sample Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15、 . . . . . . . . . . . . 6 6.2 Laboratory Sample Mixing Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 7 Test Apparatus Measurement Integrity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16、. . . . . . . . . . . . . 7 7.1 Glassware Verification Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 7.2 Test Equipment Verification Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17、 . . . . . . . . . . . . . . . 7 8 Analytical Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 8.1 Overview of Methods Considered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18、 . . . . . . . . . . . . . . . . . . . . . . . . . 8 8.2 Centrifuge Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 8.3 Graduated Cylinder Method . . . . . . . . . . . . . . . . . . . . . . . . .
19、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 8.4 Reduced Volume Distillation Method (Laboratory Referee Method) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Annex A Laboratory Testing Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
20、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Annex B Prior NEL Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Figure 1 Graduated Cylinder . . . . . . . . . . . . . . . . . . . . . . .
21、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Tables 1 Water Injection Testing Tolerances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2 Density Meter Specifications . . . . .
22、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3 Weigh Scale Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4 Centrifuge Tube Cal
23、ibration Table Example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5 Weigh Scale Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 6 Reference
24、Oil Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7 Graduated Cylinder Method Results for Light Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 8 Gr
25、aduated Cylinder Method Results for Heavy Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 9 Centrifuge Method Results for Light Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 10 Centrifug
26、e Method Results for Heavy Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 11 Distillation Method Results for Light Oil. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 12 Distil
27、lation Method Results for Heavy Oil. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 v1 Recommended Practice for Field Analysis of Crude Oil Samples Containing from Two to Fifty Percent Water by Volume 1 Scope The purpose of this document is t
28、o provide the user with recommended field methods of sampling, sample handling and analysis for high water content streams up to 50 % water on a volumetric basis. In particular, this RP was developed giving consideration to offshore installations (both floating and fixed platforms). These installati
29、ons are generally subject to motion and vibrations, have minimal laboratory equipment, and perform S&W analysis with multi- skilled operations personnel as opposed to laboratory chemists. The techniques described, however, are also applicable to onshore locations. This document provides design and o
30、perating guidelines for sampling, sample handling and sample analysis of high water content streams, up to 50 % water by volume. As a guide, this RP targets a relative accuracy of 5 % of reading up to a maximum of 50 % water content as a qualifier for the various methods described herein. For exampl
31、e, the corresponding absolute accuracy for a 10 % water content stream is 0.5 % and for 20 % water content is 1.0 %. This recommended practice may involve hazardous materials, operations, and equipment. This RP does not purport to address all of the safety problems associated with its use. It is the
32、 responsibility of the user of this RP to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. The laboratory testing contained within this RP (see Annex A) is based on a single laboratorysingle operator set of results. As with oth
33、er API standards for field S&W determination methods, no precision and bias calculation was performed and therefore, no inter-laboratory or round robin style testing was performed. The results of the testing of the various methods are primarily intended to provide a general comparison between differ
34、ent methods to facilitate operational choices. 2 References 2.1 Normative API MPMS Chapter 8.2 (ASTM D 4177), “Automatic Sampling of Petroleum and Petroleum Products” API MPMS Chapter 10.2 (ASTM D 4006), “Determination of Water in Crude Oil by Distillation” API MPMS Chapter 10.3 (ASTM D 4007), “Stan
35、dard Test Method for Water and Sediment in Crude Oil by the Centrifuge Method (Laboratory Procedure)” API MPMS Chapter 10.7 (ASTM D 4377), “Standard Test Method for Water in Crude Oils by Potentiometric Karl Fischer Titration” API MPMS Chapter 20.1, “Allocation Measurement” ASTM D 95 1 , Standard Te
36、st Method for Water in Petroleum Products and Bituminous Materials by Distillation 2.2 Informative a) API High Water Content ProjectPhase II Analytical Test MethodsFinal Report, May 5, 2005. 1 ASTM, 100 Barr Harbor Drive, West Conshohocken, Pennsylvania 19428-2959, www.astm.org2 API RECOMMENDED PRAC
37、TICE 87 b) National Engineering Laboratory (NEL) Joint Industry Project Final Report: The Measurement of High Water Content Oil/Water Mixtures by Electronic Methods (published in 1998). c) Taylor, B. N., Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 1995
38、Edition. d) Taylor, B. N., The International System of Units (SI), NIST Special Publication 330, 2001 Edition. 3 Terms and Definitions The majority of terms used in this RP are defined within API MPMS Chapter 20.1 or other related chapters and are therefore not defined here. Following are the terms
39、that are specific to this RP: 3.1 aliquot A small portion of a larger sample which is analyzed in a laboratory and assumed to represent to whole sample. 3.2 bubble point (in non-stabilized hydrocarbon liquids) The lowest pressure at which the liquid remains fully in the liquid state (see also gas br
40、eak-out). 3.3 gas break-out (in non-stabilized hydrocarbon liquids) The act of dissolved gas coming out of liquid solution and residing as free gas within the predominately liquid flow (see also bubble point). 3.4 jet mixer A system of pump(s) and nozzle(s) where a small portion of a stream is extra
41、cted and pumped and then re-injected through a nozzle back into the stream in order to provide turbulence within the stream and mix free water and oil such that a representative sample may be extracted at a point downstream. 3.5 lab mixing system A system similar to an automatic sampler circulating
42、mixing system but located in a laboratory where it is used to re- mix a large sample for aliquot delivery. 3.6 slip stream (in single phase liquid flows) A stream or bypass line of approximately the same velocity as the main stream utilized for extracting representative proportional-to-flow samples
43、(sometimes referred to as fast loop). 3.7 static mixer A series of internal obstructions designed to use the flowing velocity force of the stream to mix and evenly distribute water throughout the pipe cross-section. 4 Symbols and Abbreviated Terms 4.1 Symbols and Nomenclature plus or minus “rho” sta
44、nds for density4 API RECOMMENDED PRACTICE 87 5.1 Automatic Sampler and Stream Mixing Recommendations Since no specific testing has been conducted for this recommended practice, a conservative installation design approach should be taken. Furthermore, lighter crude oil or condensate presents the grea
45、test difficulty in acquiring representative samples. This is due to phase separation which depends on the density difference between water and crude oil and a relatively lower emulsion viscosity. Higher viscosity emulsions tend to suspend water better than lower viscosity emulsions. Therefore, light
46、 crude oil applications should be considered to be more difficult than heavier, more viscous crude oils. Following are the recommendations for stream mixing and automatic sampling systems: 1) The design of the automatic sampling system, inclusive of the probe, extraction tubing, receiver, and sample
47、r circulating/mixing system should be in accordance with API MPMS Chapter 8.2. Additionally, in-line mixer systems should be employed on all high water content situations regardless of the stream velocity. API MPMS Chapter 8.2 provides that in-line mixers are not needed if the velocities are suffici
48、ently high. However, this only applies to low water content situations. 2) The recommended installation includes a properly designed static mixer or a jet mixer. The orientation should be in a vertical down flow pipe. The sample probe (for automatic or spot samples) should be within two to three pip
49、e diameters from the exit of the mixer. 3) If vertical down flow is not a viable option, a vertical up flow orientation is also adequate provided a mixer is installed upstream and that the stream velocity is sufficient so that water droplets will not back flow. 4) If a vertical orientation is not possible the sample probe may be installed in horizontal pipe, provided a mixing device is installed upstream. The sample probe should be located immediately downstream of the mixer since higher water content streams tend to separate into a layered oil/water flow very quickly. 5) All i
