1、Recommended Practice on Determining the Static Gel Strength of Cement FormulationsANSI/API RECOMMENDED PRACTICE 10B-6FIRST EDITION, AUGUST 2010REAFFIRMED, APRIL 2015ISO 10426-6:2008 (Identical), Petroleum and natural gas industriesCements and materials for well cementingPart 6: Methods for determini
2、ng the static gel strength of cement formulationsSpecial NotesAPI publications necessarily address problems of a general nature. With respect to particular circumstances, local,state, and federal laws and regulations should be reviewed.Neither API nor any of APIs employees, subcontractors, consultan
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14、o be addressed to the director.Generally, API standards are reviewed and revised, reaffirmed, or withdrawn at least every five years. A one-timeextension of up to two years may be added to this review cycle. Status of the publication can be ascertained from theAPI Standards Department, telephone (20
15、2) 682-8000. A catalog of API publications and materials is publishedannually by API, 1220 L Street, NW, Washington, DC 20005.Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW,Washington, DC 20005, standardsapi.org.iiiiii Contents Page API Fo
16、reword 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 static gel strength apparatus . 4 8 Test method using intermi
17、ttent 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 of national standards bodies (ISO member bodies). The work o
18、f 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. International organizations, governmental and non-governmenta
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20、 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 approval by at least 75 % of the member bodies casting a vote. Atte
21、ntion 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 Committee ISO/TC 67, Materials, equipment and offshore structures f
22、or 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 and materials for well cementing: Part 1: Specification Part 2:
23、 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 at atmospheric pressure Part 6: Methods for determining the st
24、atic 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 mitigation, plugging operations and certain annular flow circumsta
25、nces. 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 couette-type rotational viscometer. More recently, specialized
26、 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 a static cement slurry. This part of ISO 10426 provides the t
27、esting 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 results obtained by the three types of instruments described in th
28、is 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, where practical, U.S. Customary (USC) units are included in b
29、rackets 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 typically marked in one degree increments, thus temperature val
30、ues 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 is related to precision, or reproducibility of a measurement.
31、 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 accurate but not precise, precise but not accurate, neither o
32、r 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 cementing Part 6: Methods for determining the static gel strength o
33、f 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 references The following referenced documents are indispensab
34、le 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 and natural gas industries Cements and materials for well cem
35、enting 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 from the true vertical depth and the fluid densities in the well
36、bore. 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 strength CSGS Specific static gel strength of a cement in whic
37、h 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 strength is measured in pascals or newtons per square metre (po
38、unds 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 gel strength SGS Shear strength (stress) measurement derived f
39、rom 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 liquid additives and mixing water are required to test a slu
40、rry 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 Method Applicable sampling techniques for the dry cement or ceme
41、nt 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 measured with a thermocouple or thermometer capable of measuring
42、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 thermometer) annually. NOTE Descriptions of commonly used sampl
43、ing 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 10426-2:2003, Clause A.1. NOTE The density of the cement slu
44、rry 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 can be heated and pressurized according to a simulated cement
45、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 (0,2/min). The initial stirring to simulate placement in the w
46、ell 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 the slurry in the test cell is increased in accordance with th
47、e 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-measuring system shall be calibrated to an accuracy of 2 C ( 4 F). Ca
48、libration 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 pr
49、ocedure 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 conditions during the batch mixing time. The pressure at this time shall be atmospheric. The stirring is typically maintained at 2,5 r/s 0,25 r/s (150 r/min 5 r/min). If there is no batch mixing time, omit this step. 6.2.2 Calculate the expected time to bottom and the expected placement time required to displace the cement to the flow zone. Ramp the cement slurry to
