Moyno 280XT Elastomer Operational Guidelines
Moyno 280XT Elastomer Operational Guidelines Index 1. Overview... 3 2. Field Test Observations... 3 3. Recommended Operational Compressions... 3 Adjusting the Temperature Range Based on Actual Shop Fit... 4 Sensitivity of Operational Compression Recommendations... 4 Differential Pressure Loading... 4 4. 280XT Fit Recommendations... 5-6 The designs and specifications for the tools described in this instruction manual were in effect at the time this manual was approved for printing. National Oilwell Varco, whose policy is one of continuous improvement, reserves the right to discontinue models at any time, or to change designs and specifications without notice or without incurring obligation.
1. Overview One of the purposes of the 280XT field test program was to establish relationships between reliability and operational loading that would form the basis for Operational Guidelines upon 280XT commercialization. Operational compression (e.g. fit ) is of particular interest with 280XT because its high compressive strength will induce more stress into the elastomer for a specific compression level than will a softer elastomer. Field performance and reliability during the program was excellent if both the operational compression and differential pressure loading recommendations were followed, so a high degree of confidence has been gained concerning the appropriateness of the recommendations contained in this document. 2. Field Test Observations The following was learned during the field test program: The minor diameter of 280XT stators has always gotten larger during use, reducing operational compression. Compression set and wear are the root causes of the observed diameter change and their contribution to the change will vary based on the application. This result is not common in power section elastomers and it s a reflection of 280XT s excellent fluid compatibility. The increase in 280XT minor diameter is desirable since it dovetails with the natural tendency for wells to get hotter with increased measured depth. As temperatures increase, 280XT naturally decreases its operational fit to reduce elastomer stress. An elastomer that has experienced compression set does not fully rebound to its initial shape after loading. It s thought that in a power section the majority of the compression set is realized in the first 10-20 hours of operation and the rate of change will decline after that. 280XT stators continued to produce significant power and torque even after a clearance fit was obtained. High ROPs were also obtained with operational fits below 1%, so elevated operational fits are not needed for fast drilling. Only one stator failed during the test program and its operational fit exceeded 3%. 2. Recommended Operational Compressions Based on the above, the following green operational compression range is considered optimal, while the other zones are acceptable, but suboptimal and they therefore may result is reduced performance. Compression % Comments = ~ 0.5 to 1.0% This range is considered sub-optimal but acceptable. Due to observed 280XT wear rates the possibility exists that a clearance fit will be obtained during the run. Field tests, however, indicate that this may not necessarily result in an observable decline in ROP. = ~ 1.0 to 2.0% This is the preferred, optimal compression range. Based on observed wear rates, it s expected that operational compression will be maintained during the entire run. = ~ 2.0 to 2.5% This range is above optimal levels and operational data is insufficient to comment on life expectancy. The initial compression represents a worst case loading, which will likely get into the green zone after 25-50 hours of operation as compression set is realized. The tables on pages 5 and 6 identify the temperatures at which the above compressions would be realized for the models that have been evaluated. The temperature ranges for each fit are not absolute and will change based on the actual rotor and stator dimensions. They should therefore be used for reference and size selection purposes only. The actual temperature ranges associated with each zone can be estimated by using the Change in range for 0.001 shop fit change number in the far right column. The example on page 4 shows how this is done: www.nov.com downhole@nov.com 3
Moyno 280XT Elastomer Operational Guidelines Adjusting the Temperature Range Based on Actual Shop Fit: Model = 475M7838 2 Actual shop fit = -0.005 Change/0.001 = 5.3 F Nominal Shop fit = -0.009 Discussion: The shop fit is 0.004 tighter than nominal. The 2 temperature range should be moved 21 F to the left due to the tighter fit (i.e. 5.3 F x 4 = 21.2 F). The new green zone range is ~ 150 225 F instead of the nominal 175 250 F. Sensitivity of Operational Compression Recommendations The operational temperatures for which operation of a specific 280XT power section fit is recommended are not absolute. In other words, if the recommended temperature range is 150-225 F, going from 225 F to 230 F does not mean that the stator will experience damage at 230, but not at 225 F. Inaccuracies in measurements and the contribution of other operational loading conditions will also affect the temperature range in which 280XT can be used. A good practice is to reduce the loading provided by another operational factor, say differential pressure or flow rate, if the calculated operational fit is at or above the top of the recommended temperature range. Differential Pressure Loading 280XT field testing has shown that a differential pressure loading of up to 100 psi/stage at 250 F produces a desirable combination of ROP and reliability. Although this loading level is the same as that recommended for UF114, 280XT has drilled at rates much higher than UF114, sometimes drilling over 3,000 ft in 24 hours. This is due to 280XT s enhanced mechanical properties that improve the ability of a conventional power section to respond to instantaneous bit torque demands and increase the effective transfer of power to the formation. The graph below describes the maximum recommended pressure/stage for 280XT for different operational temperatures. Loading recommendations change based on temperature due to an elastomer s natural tendency to loose strength as operational temperature increases. Pressure / Stage psi (kpa) 150 (1035) 125 (860) 100 (690) 75 (515) 50 (345) 150 138 Max Recommended Differential Pressure / Stage 125 112 100 90 80 70 60 50 25 (170) 0 150 175 200 225 250 275 300 325 350 375 (66) (79) (93) (107) (121) (135) (149) (163) (177) (191) Operational Temperature o F ( o C) 4
4. 280XT Fit Recommendations (October 2012) 475M4563 o F 3 100 125 150 175 200 225 250 275 300 325 350 0.006 2.414 375 400-0.020 2.440-0.054 2.474 0.008 2.495 1.5 1.5-0.012 2.515 475M5683 2.503 4.5 o F -0.024 2.527 2.5 2.5-0.048 2.551 475M7826 Std Std 0.014 2.734 2.748 5.8 o F 0.000 2.748 475M7831 0.000 2.688 2.688 5.6 o F 475M7838 0.019 2.601 2.620 5.3 o F -0.009 2.629 475M7850-0.011 2.710 2.699 6.4 o F 475M91040 Std STD -0.002 2.673 2.671 6.6 o F -0.016 2.687 500M6780 Std Std 0.019 2.615-0.014 2.648 3 Nominal Shop Fit Minor Diameter Average Rotor Diameter Change in range for 0.001 shop fit change 2.420 4.6 o F 2.634 5.1 o F o C 38 52 66 79 93 107 121 135 149 163 177 191 204 Operational Compression =~0.5 to 1.0% =~1.0 to 2.0% =~2.0 to 2.5% compression 5 www.nov.com downhole@nov.com
Moyno 280XT Elastomer Operational Guidelines 280XT Fit Recommendations (Continued) 650M91040 Std Std 0.012 3.642 3.654 2.9 o F 675M4548 0.006 3.504 3.510 3.5 o F 675M4570 0.006 3.504 3.510 3.5 o F -0.022 3.532 675M5650 o F 100 175 200 225 250 275 300 325 350 375 400 Shop Nominal 125 150 Fit Std 0.031 3.543-0.012 3.586 3.574 3.7 o F 675M6750-0.001 3.740 3.739 4.0 o F -0.028 3.767 675M7821 HT Std Std 0.015 3.803 3.817 4.6 o F 675M7829 HT 0.005 3.803 3.808 3.8 o F 675M7830 0.016 3.992 4.008 5.0 o F 0.004 4.004 675M7833 HTS -0.005 3.995 3.990 5.2 o F 675M7835 HTS 0.015 4.130 4.145 5.1 o F 675M7850 0.016 3.993 4.008 5.0 o F -0.015 4.024-0.005 4.013 700M7864 4.008 4.6 o F -0.027 4.035 800M4553 0.007 4.103 4.110 3.2 o F 800M6740 0.025 4.261 4.286 3.7 o F Minor Diameter Average Rotor Diameter Change in range for 0.001 shop fit change o C 38 52 66 79 93 107 1 21 135 149 163 177 191 20 4 Operational Compression =~0.5 to 1.0% =~1.0 to 2.0% =~2.0 to 2.5% compression 6
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