Fiberglass casing (glass-reinforced epoxy, or GRE casing) is not a drop-in replacement for steel casing in every well. It is one casing-string path that makes sense when corrosion, workover cost, or handling weight drive the material question, and when the well’s pressure, temperature, and fluid picture can be checked against what the composite string is actually offered for. You lose time when the enquiry says “send fiberglass casing” before the casing job, the wellbore fluid, the pressure-class intent, and the connection plan are written down.
This page is a selection and RFQ guide for the casing string. It does not repeat the older fiberglass casing articles on corrosion benefits, and it does not cover downhole tubing acceptance or screen design. Use it when your open question is still whether fiberglass casing belongs on the shortlist and what to send so quotes come back comparable.
Who this page is for
- Drilling and completion engineers deciding whether a GRE casing string fits a casing-damage repair, a water-source well, a CBM well, or another corrosive casing program.
- EPC and project teams keeping casing, tubing, and screen scopes apart before the RFQ hardens.
- Procurement engineers writing an enquiry that names operating conditions and interfaces, not just a diameter.
Start with the casing job, not the diameter row
Write these down before you freeze a nominal size. Blank fields force the supplier to guess, and the usual wrong guess is the product family (tubing, screen, or line pipe), not only the size.
| Condition field | What to capture | Why it matters for fiberglass casing |
|---|---|---|
| Casing job | New casing string, casing-damage repair or liner inside damaged steel, water-source well, CBM well, other | The live product pages name repair, water-source, and CBM straight wells; anything else needs a suitability check |
| Well geometry | Hole size, setting depth class, vertical or deviated, string length | Separates “wrong size class” from “unworkable composite path” |
| Fluid and corrosion drivers | Produced or formation water chemistry, CO₂ or H₂S notes, steel casing failure history | Corrosion resistance is the main reason to consider GRE; confirm it against your actual fluid |
| Pressure-class intent | Internal and external (collapse) loads you can share | The pages cite a pressure range as published; collapse and setting depth need engineering review |
| Temperature envelope | Continuous and upset temperature at depth | Resin systems have temperature limits; confirm against the offered datasheet |
| Connection intent | Thread or coupling type, crossover to steel if any | Composite connections need their own make-up and running practice |
| Running and later operations | Rig handling rules, cementing plan, later workover or drill-out expectations | Light weight helps only if yard and rig practice suit composite tubulars |
| Evidence already held | Failure history, logs, prior workover reports | Separates a material decision from a design-ownership gap |
If your open question is downhole GRE tubing acceptance rather than the casing string, use Downhole GRE Tubing: Qualification Checks Before Purchase. This article sits on a different object: the casing string itself.
When fiberglass casing fits
Lean toward fiberglass (GRE) casing when most of these are true:
- Corrosion or steel casing life is the main driver. The live product pages frame GRE casing for corrosion resistance and long service life versus conventional steel casing in suitable wells. Check that framing against your fluid analysis and failure history.
- The job sits inside the applications the catalogue names. As published, these are casing-damage well repair, water-source wells, and CBM straight wells, plus other corrosive casing programs where suitability is confirmed with CNPS. Do not assume an unlisted well type is covered.
- Your pressure intent can be checked against the offered range. The product pages cite a pressure range of 10 MPa to 25 MPa as published. Treat that as a starting point for the offer, not a rating for your well, and have collapse load at setting depth reviewed separately.
- Size sits near the published production range. The pages list DN100 to DN250 as published, with design and production to customer demands. Sizes outside that range are a design question, not a stock item.
- Weight and handling matter. GRE casing is lighter to handle and run than steel, which helps on repair jobs and small rigs, as long as your crew can follow composite running procedures.
- Casing stays a separate scope. Keep the casing RFQ apart from tubing, screens, and surface line pipe, each with its own acceptance criteria.
Field check: if the well’s temperature, collapse load, or later drilling plan is still unknown, settle that first. Forcing a GRE casing RFQ before the load case exists produces quotes you can’t compare.
When steel casing or another path usually wins first
| Situation | Lean toward first | Why fiberglass casing is secondary |
|---|---|---|
| Load case (collapse, tension, temperature) still open | Casing design review | Wrong architecture, not wrong material |
| Need is downhole tubing, not casing | Tubing qualification path | Tubing and casing have different acceptance checks |
| Need is a screened or slotted interval | GRE screen path | A screen is a filtration object, not a blank casing joint |
| Need is surface gathering or injection piping | Line-pipe spec path | Line pipe is not a casing string |
| Duty clearly outside the offered pressure or temperature language | Steel or corrosion-resistant alloy casing, as engineered | Don’t stretch a composite rating in an email |
For a screened interval, see GRE Screen Tube: When Fiberglass Screens Fit CBM & Corrosive Well Sand Control (Selection & RFQ Fields). For surface piping, see How to Spec GRE/FRP Line Pipe from Pressure, Temperature, and Medium.
Casing vs tubing vs screen vs line pipe: keep the scopes separate
GRE casing, GRE tubing, GRE screens, and GRE line pipe come from the same family of filament-wound epoxy composites, but each is its own design and RFQ object.
| Scope | Typical decision | Where to go |
|---|---|---|
| GRE casing (this page) | Whether a composite casing string fits; size and pressure class as offered; connection and running plan | This article and the product page linked below |
| GRE tubing | Qualification and acceptance before purchase | Tubing qualification article (linked above) |
| GRE screen | Screened interval and filtration intent | Screen tube article (linked above) |
| GRE/FRP line pipe | Pressure, temperature, and medium for surface piping | Line-pipe spec article (linked above) |
If the naming itself is the confusion, GRP vs GRE Pipes: What’s the Difference? explains the resin difference.
Field check: one PO line that mixes “GRE casing + tubing + screens” without separate acceptance criteria creates the wrong evidence pack for every scope.
What the live product pages already say (and where they stop)
As published on the CNPS Fiberglass Casing and GRE Casing product pages:
- Construction: downhole GRE casing made by micro-controlled filament winding of epoxy resin and high-strength glass fiber roving.
- Applications: casing-damage well repair, water-source wells, and CBM straight wells, with other corrosive casing programs subject to confirmation.
- Production range: diameter DN100 to DN250 and pressure 10 MPa to 25 MPa, with design and production available to customer demands.
- Standards referenced: API 15HR (Specification for High Pressure Fiberglass Line Pipe) and SY/T 6267-2006, the Chinese industry standard for high-pressure fiberglass line pipe (since replaced by SY/T 6267-2018). Both are written for line pipe and its fittings, not for casing strings. CNPS supplies API 15HR certified fiberglass pipe; ask for certificate copies with the offer, confirm which products and sizes they cover, and ask which standard and test basis the casing string itself is made and tested to.
- Page note: parameters are general design information and are not an inspection basis on their own. Confirm final dimensions and ratings with CNPS.
- Price: quoted on request. No price is given here.
Where this page stops: collapse ratings at your setting depth, temperature limits for your fluid, connection make-up values, and certificate scope belong in the formal offer and engineering documents, not in a general guide like this one.
RFQ fields that keep fiberglass casing quotes comparable
Copy these into your enquiry so replies line up side by side.
| RFQ field | What to write | Honesty check |
|---|---|---|
| Casing job | New string, repair liner inside damaged steel, water-source, CBM, other | Say so if the job type is still open |
| Well identity | Field and well ID, vertical or deviated, setting depth class, string length | Unknown beats invented geometry |
| Fluid and corrosion notes | Water chemistry, CO₂ or H₂S notes, steel failure history | Attach lab data where you have it |
| Pressure intent | Internal pressure and external collapse loads | Compare against the offered 10 to 25 MPa framing; don’t invent a rating |
| Temperature | Continuous and upset at depth | Confirm against the offered datasheet |
| Size and connection | Nominal size if known, thread or coupling type, crossover to steel | Or ask engineering to propose |
| Cementing and running | Cement plan, centralizers, rig handling limits | Composite running practice differs from steel |
| Related scopes | Separate RFQs for tubing, screens, or line pipe, or “none” | Keep objects separate |
| Documents | Datasheet, API 15HR certificate copies and the products they cover, the standard and test basis for the casing string, hydrotest records, inspection and traceability plan | No made-up certificate numbers |
| Project owner | Who owns the load case and acceptance | Needed for comparable replies |
When you’re ready to match an offered configuration, use the Fiberglass Casing product page. For what reviewers expect in the test file, see FRP/GRE Pipe Testing Documents: What Third-Party Reviewers Expect Before Acceptance.
FAQ
Is fiberglass casing the same as GRE casing?
In oilfield use, “fiberglass casing,” “GRE casing,” and “FRP casing” usually describe the same product family: filament-wound glass fiber with an epoxy resin system. Always confirm the resin system, size, connection, and standard reference on the offered datasheet rather than relying on the label.
Where does fiberglass casing make the most sense?
As published on the CNPS product pages, the named applications are casing-damage well repair, water-source wells, and CBM straight wells. Other corrosive casing programs can fit, but suitability should be confirmed against your fluid, pressure, and temperature data.
Can fiberglass casing replace steel casing in any well?
No. It fits when corrosion or handling weight drive the decision and the load case sits inside what the composite string is offered for. High collapse loads, high temperatures, or a duty outside the offered range usually point back to steel or corrosion-resistant alloy casing.
What pressure range is published for CNPS fiberglass casing?
The product pages cite 10 MPa to 25 MPa and DN100 to DN250 as published, with design to customer demands. That is general design information. Confirm the rating, including collapse at your setting depth, in the formal offer.
Is GRE casing the same as GRE tubing?
No. They share materials, but casing and tubing are different strings with different loads and acceptance checks. Use the tubing qualification article for tubing and this page for the casing string.
What should I send to get a useful quote?
Send the casing job, well geometry, fluid notes, pressure and temperature intent, size and connection, cementing plan, and the documents you need, such as API 15HR certificate copies and the standard the casing string is made and tested to. The RFQ table above lists each field.
Talk to an engineer before the RFQ goes out
If you’re unsure whether fiberglass casing fits your well, send the casing job, fluid data, and load case to our team. We’ll tell you whether a GRE string is a sensible path and what the offer should cover. Talk to an Engineer or email sales@cnps.com.
