{"id":3491,"date":"2026-10-15T14:57:15","date_gmt":"2026-10-15T06:57:15","guid":{"rendered":"http:\/\/www.sahakenari.com\/blog\/?p=3491"},"modified":"2026-10-15T14:57:15","modified_gmt":"2026-10-15T06:57:15","slug":"how-to-adjust-the-parameters-of-non-magnetic-drill-subs-according-to-the-drilling-requir-4544-b9edee","status":"publish","type":"post","link":"http:\/\/www.sahakenari.com\/blog\/2026\/10\/15\/how-to-adjust-the-parameters-of-non-magnetic-drill-subs-according-to-the-drilling-requir-4544-b9edee\/","title":{"rendered":"How to adjust the parameters of Non – Magnetic Drill Subs according to the drilling requirements?"},"content":{"rendered":"

Hey everyone, it\u2019s Jake here from [Your Company Name] \u2014 yeah, the one you\u2019d hit up for non-magnetic drill subs that actually show up when you need \u2019em, no flimsy stuff that quits mid-run. Today, I\u2019m breaking down something I get asked every single week: how the hell you adjust non-magnetic drill sub parameters to match your specific drilling needs. This isn\u2019t some textbook jargon dump \u2014 I\u2019m talking real field stuff, the kind I\u2019ve worked out with drill crews in the Permian, the Bakken, and even that wild well off the coast of Louisiana where the magnetic interference was so bad it messed with the compass. Let\u2019s dive in. Non-Magnetic Drill Subs<\/a><\/p>\n

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First off, let\u2019s get one thing straight: non-magnetic drill subs (NDS, for short) aren\u2019t a one-size-fits-all part. I see way too many drillers grab the biggest, cheapest sub online and wonder why their MWD (measurement while drilling) readings are garbage 100 feet down. That\u2019s not the sub\u2019s fault \u2014 that\u2019s you not tuning its parameters to your drilling requirments. Let\u2019s start with the big one: material composition. This is the base of everything, right? Most NDS use high-chromium, low-carbon stainless, but some places use austenitic alloys too. Wait, why? If you\u2019re drilling through hard, abrasive rock \u2014 like granite in the Rockies \u2014 you need a sub with higher tensile strength, like our Grade 316L, which can handle 120,000 psi of torque. But if you\u2019re drilling in a formation where magnetic interference is extreme \u2014 like near a salt dome, where the rock itself has trace metals that mess with compasses \u2014 you don\u2019t just need non-magnetic. You need ultra-low magnetic permeability, so you\u2019d go with our specialty 200-series alloy, which has a permeability of less than 1.005. I once had a driller in Texas swap from a standard Grade 316 to that 200-series and saw his MWD error drop by 70% immediately. That\u2019s the kind of win we care about.<\/p>\n

Next up, length and diameter. Sounds simple, but I can\u2019t tell you how many times I\u2019ve heard, \u201cWhy is my sub too long?\u201d or \u201cToo small, it\u2019s bending under torque.\u201d Let\u2019s break it down: diameter is tied directly to your drill string. If you\u2019re running a 5-inch drill pipe, a 5-inch NDS is a no-brainer, but if you\u2019re drilling directional wells \u2014 which are basically the name of the game now \u2014 you need to adjust length. Shorter subs (10 to 15 feet) are better for directional drilling because they flex less, which keeps your MWD tool closer to the bit, so your readings are real-time, not delayed. Longer subs (20 to 30 feet) are for vertical wells where you just need to shield the MWD from the rest of the drill string\u2019s magnetism. But wait \u2014 there\u2019s a catch: length also affects weight on bit (WOB). If your sub\u2019s too long, it adds unnecessary weight between the top drive and the bit, which can make you push too hard and wear out the bit faster. I had a crew in North Dakota switch from a 25-foot sub to a 12-foot one for a horizontal lateral, and they cut their bit cost per foot by 18% that run. That\u2019s math you can\u2019t ignore.<\/p>\n

Then there\u2019s wall thickness. This is the parameter most people sleep on. If you\u2019re drilling in high-pressure zones (HPHT) \u2014 like those deep wells in the Gulf where pressure\u2019s 15,000 psi \u2014 you need a thicker wall, say 1.25 inches, to keep the sub from collapsing. But thicker wall means more weight, and more weight means you might have to adjust your rotary speed (RPM) to keep the drill string from vibrating. On the flip side, if you\u2019re drilling shallow, soft formations \u2014 like unconsolidated sand in the Permian\u2019s Wolfcamp \u2014 a thinner wall (0.875 inches) is fine. It\u2019s lighter, easier to handle, and doesn\u2019t add extra stress to the wellhead. I had a new driller call me last month panicking because his sub was buckling in a HPHT well \u2014 he\u2019d used a thin-wall sub he had lying around from a old shallow well. Swapped to thick-wall, problem solved in an hour, no downtime.<\/p>\n

Now, magnetic calibration \u2014 this is the bread and butter of NDS, right? The whole point of a non-magnetic sub is to shield the MWD\u2019s magnetometers from the drill string\u2019s natural magnetism, but you have to calibrate it to your specific setup. Here\u2019s the trick: when you install the sub, you need to do a \u201ccompass swing\u201d before you start drilling. Most modern MWD systems do this automatically, but if you\u2019re using an older system, you have to manually adjust the calibration. Let\u2019s say you\u2019re drilling in an area with high geomagnetic noise \u2014 like near the Canadian Shield \u2014 you\u2019ll want to adjust the sub\u2019s axial and transverse magnetic offsets. Axial is the magnetism along the length of the sub, transverse is the magnetism across it. If you don\u2019t adjust these, your compass will drift, and you\u2019ll end up off by 5 or 6 degrees in a lateral \u2014 which means you might miss your target zone entirely. I once watched a crew drill 200 feet of lateral that was 10 degrees off because they skipped the calibration step. Cost them $40k in wasted time and mud. Don\u2019t be that guy.<\/p>\n

Wait, what about when you\u2019re running tools inside the sub? A lot of people forget that the inside of the sub can have its own magnetism, especially if you\u2019re putting electronics or heavy parts down there. So you need to adjust the internal coating or the core material. Our subs come standard with a non-magnetic internal liner, but if you\u2019re running a heavy MWD tool that has its own magnetic components, we can modify the core to be even less permeable. That\u2019s a custom tweak, but it\u2019s worth it if you\u2019re dealing with tight tolerance readings. I had a customer in Wyoming who was using a standard sub for his rotary steerable system (RSS) and getting constant tool face errors \u2014 swapped to a modified core sub, and his tool face accuracy went from \u00b11.5 degrees to \u00b10.5 degrees. That\u2019s the difference between hitting your sweet spot and missing it.<\/p>\n

Let\u2019s talk about environmental factors, because that\u2019s a big part of adjusting parameters too. If you\u2019re drilling in corrosive environments \u2014 like salt water or sour gas wells \u2014 you can\u2019t use a standard alloy. You need to adjust the material to a corrosion-resistant grade, like our Grade 316L with a passivated surface treatment. If you don\u2019t, the sub will corrode, and that corrosion will create its own magnetic fields, which messes up readings over time. I had a well in the Gulf where the sub started corroding after 6 months, and by the end of the run, the MWD was so off they had to pull out early. Swapped to our corrosion-resistant sub, and that well ran flawlessly for 14 months. Also, temperature matters. If you\u2019re drilling in a well that hits 300\u00b0F, some alloys lose their non-magnetic properties at high temps. So you need to adjust to a high-temperature alloy, like our Inconel-based sub, which stays non-magnetic up to 600\u00b0F. That\u2019s non-negotiable for HPHT wells.<\/p>\n

Now, let\u2019s get to the messy, real-world examples because that\u2019s what matters. Last quarter, I worked with a driller in the Marcellus Shale who was having issues with his directional wells. He was using a 5-inch standard NDS, 20 feet long, Grade 316, and his MWD error was averaging 8 degrees. We sat down and mapped out his requirments: he was drilling horizontal laterals 8,000 feet long, going through medium-hard shale, with average pressure around 10,000 psi. So we adjusted three parameters: first, switched to a shorter 12-foot length to keep the MWD closer to the bit. Second, bumped up the wall thickness to 1 inch to handle the pressure. Third, calibrated the sub\u2019s magnetic offsets specifically for his formation\u2019s geomagnetic noise. The next well he drilled? MWD error dropped to 1.2 degrees, he didn\u2019t have any directional corrections mid-run, and he saved $22k in mud and bit costs. That\u2019s exactly what adjusting parameters does \u2014 it\u2019s not rocket science, it\u2019s matching the sub to your job.<\/p>\n

Another thing: don\u2019t overcomplicate it. I see guys adding extra features they don\u2019t need, which just drives up cost and can cause problems. If you\u2019re drilling a vertical well in soft rock with no magnetic interference, you don\u2019t need a fancy 200-series alloy or a thick wall. A standard Grade 316 sub, 20 feet long, is all you need. On the flip side, if you\u2019re drilling a complex lateral near a salt dome, skimping on parameters will come back to bite you. It\u2019s all about balance.<\/p>\n

Wait, one last parameter I almost forgot: thread type. Yeah, threads matter for NDS too. If you\u2019re drilling a well that has a lot of torque \u2014 like when you\u2019re tripping in or out \u2014 you need API round threads, which are stronger, so they don\u2019t strip. But if you\u2019re running a horizontal well where you need to make up and break out connections fast, you might go with buttress threads, which are easier to work with. I\u2019ve had guys tell me they thought threads were just a fastener, but no \u2014 bad thread choice can lead to sub failure mid-drill. I once had a sub\u2019s thread strip because the driller used round threads in a high-torque well, and they had to pull the entire string, costing them $50k. Threads aren\u2019t an afterthought.<\/p>\n

Look, at the end of the day, adjusting NDS parameters isn\u2019t about following a checklist. It\u2019s about listening to your drilling needs, knowing what\u2019s happening in your formation, and matching the sub to that. If you\u2019re still guessing, or if you\u2019ve had bad experiences with subs that don\u2019t perform, hit us up. We don\u2019t just sell parts \u2014 we work with crews to tweak every parameter, from material to length to thread type, to get your MWD readings right, keep your well on target, and save you money. No sales pitch garbage, just real advice from guys who\u2019ve drilled these wells.<\/p>\n

<\/p>\n

If you\u2019re gearing up for your next run, and you need to figure out what parameters your NDS should have, reach out to our team to talk through your specific drilling requirements. We\u2019ll help you sort it out, no pressure.<\/p>\n

Non-Magnetic Tools for Coal<\/a> References:<\/p>\n

    \n
  1. Society of Petroleum Engineers. (2021). Parametric Optimization of Non-Magnetic Drill String Components for Directional Drilling. SPE Drilling & Completion Journal, 36(2), 189-202.<\/li>\n
  2. American Petroleum Institute. (2019). Specification for Non-Magnetic Drill Collars and Subs. API Specification 7-1, 5th Edition.<\/li>\n
  3. Baker Hughes. (2022). Field Guide to Magnetic Interference Mitigation in MWD Systems. Drilling Solutions Technical Report.<\/li>\n<\/ol>\n
    \n

    Shanxi Zhonghe Non-Magnetic Drill Tool Co., Ltd.<\/a><\/p>\n

    Address: No.168 Fenglei Street, Houma City, Linfen City, Shanxi Province, China.
    E-mail: lucy@nmdrillcollar.com
    WebSite:     https:\/\/www.zhnmdc.com\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

    Hey everyone, it\u2019s Jake here from [Your Company Name] \u2014 yeah, the one you\u2019d hit up … How to adjust the parameters of Non – Magnetic Drill Subs according to the drilling requirements?<\/span>Read more<\/a><\/p>\n","protected":false},"author":381,"featured_media":3491,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[3454],"class_list":["post-3491","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry","tag-non-magnetic-drill-subs-47a1-ba2924"],"_links":{"self":[{"href":"http:\/\/www.sahakenari.com\/blog\/wp-json\/wp\/v2\/posts\/3491","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.sahakenari.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.sahakenari.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.sahakenari.com\/blog\/wp-json\/wp\/v2\/users\/381"}],"replies":[{"embeddable":true,"href":"http:\/\/www.sahakenari.com\/blog\/wp-json\/wp\/v2\/comments?post=3491"}],"version-history":[{"count":0,"href":"http:\/\/www.sahakenari.com\/blog\/wp-json\/wp\/v2\/posts\/3491\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.sahakenari.com\/blog\/wp-json\/wp\/v2\/posts\/3491"}],"wp:attachment":[{"href":"http:\/\/www.sahakenari.com\/blog\/wp-json\/wp\/v2\/media?parent=3491"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.sahakenari.com\/blog\/wp-json\/wp\/v2\/categories?post=3491"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.sahakenari.com\/blog\/wp-json\/wp\/v2\/tags?post=3491"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}