1、Recommended Practice on Determining the Static Gel Strengthof Cement FormulationsANSI/API RECOMMENDED PRACTICE 10B-6FIRST EDITION, AUGUST 2010REAFFIRMED, APRIL 2015ISO 10426-6:2008 (Modified), Petroleum and natural gas industriesCements and materials for well cementingPart 6: Methods for determining
2、 the static gel strength of cement formulationsRecommended Practice on Determining the Static Gel Strengthof Cement FormulationsUpstream SegmentANSI/API RECOMMENDED PRACTICE 10B-6FIRST EDITION, AUGUST 2010REAFFIRMED, APRIL 2015ISO 10426-6:2008 (Modified), Petroleum and natural gas industriesCements
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17、ngton, DC 20005, standardsapi.org.iiiiii Contents Page API Foreword ii Foreword iv Introduction . v 1 Scope 1 2 Normative references 1 3 Terms and definitions . 1 4 Sampling . 2 5 Preparation . 2 6 Test method using rotating-type static gel strength apparatus . 3 7 Test method using ultrasonic-type
18、static gel strength apparatus . 4 8 Test method using intermittent rotation-type static gel strength apparatus 4 Annex A (informative) Critical static gel strength Additional information . 6 Bibliography 7 iv Foreword ISO (the International Organization for Standardization) is a worldwide federation
19、 of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee.
20、International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance wit
21、h the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approv
22、al by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 10426-6 was prepared by Technical Commit
23、tee ISO/TC 67, Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries, Subcommittee SC 3, Drilling and completion fluids, and well cements. ISO 10426 consists of the following parts, under the general title Petroleum and natural gas industries Cements an
24、d materials for well cementing: Part 1: Specification Part 2: Testing of well cements Part 3: Testing of deepwater well cement formulations Part 4: Preparation and testing of foamed cement slurries at atmospheric pressure Part 5: Determination of shrinkage and expansion of well cement formulations a
25、t atmospheric pressure Part 6: Methods for determining the static gel strength of cement formulations v Introduction Characterizing the static gel-strength (SGS) development of a cement slurry is an important design parameter in specific cementing environments. These include shallow-water flow mitig
26、ation, plugging operations and certain annular flow circumstances. Determining the gel-strength characteristics of a cement slurry allows the user to ascertain if the cement design is fit for a particular intended purpose. Historically, the SGS of a cement slurry was determined by a method using a c
27、ouette-type rotational viscometer. More recently, specialized instruments, including a rotating-type apparatus, an intermittent rotation-type apparatus and an ultrasonic-type apparatus (removed in the API adoption, please refer to Clause 7), have been used to measure the gel-strength development of
28、a static cement slurry. This part of ISO 10426 provides the testing protocol for determining SGS using these two types of instruments. It is necessary to note that, due to differences in sample size, apparatus configuration and method of SGS determination, there can be considerable variance in resul
29、ts obtained by the three types of instruments described in this part of ISO 10426. CAUTION Caution is necessary when using static gel-strength development testing results as the single or predominant engineering parameter of a cement slurry design or technical evaluation. In this part of ISO 10426,
30、where practical, U.S. Customary (USC) units are included in brackets for information. The units do not necessarily represent a direct conversion of SI to USC, or USC to SI, units. Consideration has been given to the precision of the instrument making the measurement. For example, thermometers are ty
31、pically marked in one degree increments, thus temperature values have been rounded to the nearest degree. In this part of ISO 10426, calibrating an instrument refers to ensuring the accuracy of the measurement. Accuracy is the degree of conformity of a quantity to its actual or true value. Accuracy
32、is related to precision, or reproducibility of a measurement. Precision is the degree to which further measurements or calculations show the same or similar results. Precision is characterized in terms of the standard deviation of the measurement. The results of calculations or a measurement can be
33、accurate but not precise, precise but not accurate, neither or both. A result is valid if it is both accurate and precise. Annex A of this part of ISO 10426 is for information only. API Recommended Practice 10B-6/ISO 10426-61 Petroleum and natural gas industries Cements and materials for well cement
34、ing Part 6: Methods for determining the static gel strength of cement formulations 1 Scope This part of ISO 10426 specifies requirements and provides test methods for the determination of static gel strength (SGS) of cement slurries and related materials under simulated well conditions. 2 Normative
35、references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced standard (including any amendments) applies. API 10B-2/ISO 10426-2:2003, Petroleum
36、and natural gas industries Cements and materials for well cementing Part 2: Testing of well cements 3 Terms and definitions For the purposes of this part of ISO 10426, the following terms and definitions apply. 3.1 bottom-hole pressure PBHHydrostatic pressure at the bottom of the well calculated fro
37、m the true vertical depth and the fluid densities in the wellbore. 3.2 bottom-hole circulating temperature TPBHCMaximum temperature encountered in a wellbore during cement slurry placement. 2 RECOMMENDED PRACTICE ON DETERMINING THE STATIC GEL STRENGTH OF CEMENT FORMULATIONS 3.3 critical static gel s
38、trength CSGS Specific static gel strength of a cement in which hydrostatic-pressure equilibrium is reached between the decayed hydrostatic pressure transmission of the cement column (and other fluids in the annulus) and the pore pressure of the formation. See Annex A. NOTE The critical static gel st
39、rength is measured in pascals or newtons per square metre (pounds force per 100 square feet). 3.4 critical static gel-strength period CSGSP Time interval required for the cement to progress from the critical static gel strength value to a static gel strength of 250 Pa (500 lbf/100 ft2). 3.5 static g
40、el strength SGS Shear strength (stress) measurement derived from force required to initiate flow of a fluid. NOTE The static gel strength is measured in pascals or newtons per square metre (pounds force per 100 square feet). 4 Sampling 4.1 General Samples of the dry cement or cement blend, solid and
41、 liquid additives and mixing water are required to test a slurry in accordance with this part of ISO 10426. Accordingly, the best available sampling technology should be employed to ensure the laboratory test conditions and materials match as closely as possible those found at the well site. 4.2 Met
42、hod Applicable sampling techniques for the dry cement or cement blend, solid and liquid additives and mixing water used in typical cementing operations can be found in ISO 10426-2:2003, Clause 4. If required, the temperature of the mix water, cement or cement blends, and liquid additives may be meas
43、ured with a thermocouple or thermometer capable of measuring temperature with an accuracy of 2 C ( 4 F). These temperatures should be recorded. Temperature-measuring devices shall be calibrated (in the case of a thermocouple) no less frequently than every three months or checked (in the case of a th
44、ermometer) annually. NOTE Descriptions of commonly used sampling devices can be found in ISO 10426-2:2003, Figure 1. 5 Preparation Prepare the test samples in accordance with ISO 10426-2:2003, Clause 5. If larger slurry volumes are needed, an alternative method for slurry preparation is found in ISO
45、 10426-2:2003, Clause A.1. NOTE The density of the cement slurry can be verified by methods found in ISO 10426-2:2003, Clause 6. API RECOMMENDED PRACTICE 10B-6/ISO 10426-6 3 6 Test method using rotating-type static gel strength apparatus 6.1 Apparatus The apparatus contains a pressure chamber that c
46、an be heated and pressurized according to a simulated cement job schedule. The SGS is calculated from the torque required to rotate a paddle of known geometry at very low speed. The rotation speed of the paddle during the SGS measurement portion of the test is normally a continuous 0,000 009 2 r/s (
47、0,2/min). The initial stirring to simulate placement in the well is typically conducted at 2,5 r/s 0,25 r/s (150 r/min 15 r/min). The rotating-type static gel strength apparatus shall be calibrated according to the manufacturers instructions. During the test period, the temperature and pressure of t
48、he slurry in the test cell is increased in accordance with the appropriate well-simulation test schedule (see 6.2.2). Determine the temperature of the cement slurry by use of an ASTM E220 classification “special” type J thermocouple located in the centre of the testing cell. The temperature-measurin
49、g system shall be calibrated to an accuracy of 2 C ( 4 F). Calibration shall be performed no less frequently than every three months. NOTE Changing the rotational speed of the apparatus can be required depending on slurry design. The permissible range of rotational speed for the apparatus is 0,000 006 9 r/s (0,15/min) to 0,000 023 1 r/s (0,5/min). 6.2 Test procedure 6.2.1 If there is a batch mixing time being used for the job, the test schedule should include this segment. The slurry should be exposed to the anticipated temperature condition
