Private Forums
Reverse Cementing
01 February 2018

Hi,

we are planning a reverse cement Job for 24" casing run in 28" hole size, the previous casing is 26" - ID - 25"

26" casing setting depth - 2700ft

24" casing setting depth 3650ft.

The Top of cement behind 24" casing is 2300ft. covering a big loss zone.

FG at 24" casing depth 10.5ppg

MW drilling was 9.1 ppg

I appreciate your help understanding what way to go- Conventional cementation or Reverse cementing.

What are the Hi-points or Low points for Both.

What is achievable having good cement bond behind casing covering the loss Zone.


If anyone has case studies , SPE papers kindly share.

Appreciate your help

Thanks & Best Regards,

Hari.



 

6 answer(s)
Augusto
Consultant [retired Shell staff]
SPREADAssociates
Total Posts: 240
Join Date: 02/09/05
I tend to agree with Wayne, i. e. spot the cement on bottom and run the casing into it as it was done decades ago with the original short liner cementing procedures.
gibsona7
Head of Well Design and Completions
MOL Group
Total Posts: 6
Join Date: 06/11/11

Hi Hari,

I have not reverse cemented, but it is an interesting conversation. I think if you start with the objectives of your cement job, the solution will follow. Usually, the objective is sufficient shoe strength / leak-off, to drill the next section. This objective implies that you want your strongest, least contaminated cement, around your shoe, which is achieved by conventional cementing.

[email protected]
D&C Project Coordinator / Decommissioning
Society of Petroleum Engineers
Total Posts: 10
Join Date: 25/01/16
Indeed I've never done reverse circulation for placement of cement other then to squeeze cement down the annulus.  Channelling is a big issue for the procedure unless one can rotate.   For you situation I would suggest "puddling" the cement.   Spot the cement on bottom using say a 7" casing stinger where you rotate while displacing to a balanced plug situation.  Then run the casing into the "puddle" of cement.  Decide what float system and what fluid to fill the casing with as it is run and landed.  Seems a 13.6  ppg or so cement with prehydrated gel mixwater would be the appropriate puddle slurry. 
dlenin
Website owner
better-cementing-for-all.org
Total Posts: 12
Join Date: 12/06/16

Hi Hari,

One of the disadvantages of conventional cementing is that as the cement raises in the annulus there is an important increase in hydrostatic obviously, but there is also an important contribution of friction pressure coming from the annular gap derived from the higher rheology of the cement slurry; the geometry of the flow path along the annulus (as described by the caliper log, min and max hole diameter, etc.) and surface return lines. This is not normally a problem, but if in a losses situation the cement would be inclined to take the path of minimum resistant, typically the losses zone, stopping its way going up in the annulus. All this is easily simulated (predicted) by the cementing company's software, and there are several alternatives to "prevent" it both embedded in the design or more of operational mitigations. The bad thing is that all this prevention or mitigation would act contrary to the main objective of primary cementing, which is mud displacement. (You know for cement slurry to displace the mud efficiently, the slurry needs to be higher density and has higher rheology).

Anyway, one "nice" alternative to remove all that friction pressure in your annulus pushing the cement to the losses zone is Reverse Cementing. Here the friction pressure is acting from or against the top (rather than from or against the bottom). In other words friction pressure would be helping you to "reduce" the hydrostatic (more like the ECD) acting on the losses zone. That is the principle. Additionally since you are pushing your mud from the top with cement, both density and rheology of the cement slurry can be (must be actually) lowered in order to achieve proper mud displacement. In this direction of flow, a heavier (than your mud) slurry would be driven by gravity (channeling, sinking) damaging your mud displacement, but a lighter slurry would try to always stay on top displacing your mud more evenly. This has an obvious effect on your annulus hydrostatic and what ECD would your losses zone see.

In general, cement bond quality in reverse cementing would be worse that conventional cementing, BUT in a case of losses situation reverse cementing has greater chances to allow you to cover your annulus with cement and allow you to attain your TOC.

The keys for reverse cementing are: Proper design of cement slurries for this condition and your casing hardware. Collar and shoe, to allow reverse flow; and good centralization (centralization here has a greater role than in conventional cementing).

I believe that this simple explanation in addition to Clayton's and Steve's would give you a good starting point to understand which way is better in your case.

The cementing company software simulation can be used to better evaluate the different scenarios, but not all available simulators can handle the simulation of reverse cementing. One of the big ones certainly can; and another won't encourage you to do it at all, but to be honest with the lower quality of cementing engineering support theses days, I would include that as a factor to consider.

Lenin Diaz

http://better-cementing-for-all.org

CDNTECHMGR
Canadian Technical Services Manager
NCS Multistage Unlimited
Total Posts: 1
Join Date: 01/12/17
Hi Hari, interesting discussion. Although I've not participated in the reverse cement job operation, I've been part of the design team that built a reverse cementing valve as well as have cemented for a number of years.
Some of the bigger advantages with reverse cementing are as follows:
  • Lower ECD's - you are allowing the weight of the cement to set itself into place as opposed to high pressure pumping to force it into place
  • Easier on the formation - there is inherently less stress on the formation and the near-wellbore during cement placement
  • Potential minimal displacement volumes (depending on where you want cement top to be)
  • Lower displacement pressure as you'll be over-balanced
  • minimized contamination inside the liner/casing
  • eliminate concerns of inefficient wiper
Some of the disadvantages:
  • Significantly more surface equipment needed to pump and handle returns (manifold for well control on casing side)
  • need to compensate for expansion with returns
  • Reverse Circ valve can be expensive
  • potential slurry contamination if well is not cleaned properly
The reason we looked at (and accomplished) reverse cementing operations was to avoid cement stringers in a ball-seat frac liner completion. The risk of an inadvertent sleeve opening event was such that it warranted a sterile liner, ie: reverse cementing. Another idea that was thrown out was the design and development of a stab-in, inner string reverse cementing setup. (not unlike a cement retainer with a resettable check valve in the inner string). There are a few papers published by Halliburton, EnCana, and possibly WFT on the subject.

I hope this helps.

Thanks,

Clayton
snas
Well Engineering Consultant and Instructor
Olango Consulting
Total Posts: 10
Join Date: 23/03/16
Hari

Never done reverse cementing but it was discussed on an air drilling job I was on. In the end we decided that a stinger cementation was much simpler.

To reverse cement you need to have the casing open at the bottom. The dis-advantage there is that any cement that gets to the shoe will U-tube up the casing and that requires careful control. Basically you need to have the inside of the casing closed and maintain pressure.

Pumping down the annulus could be a challenge depending on the wellhead seals for the casing.

Normally the barrier for a casing string needs to be at the bottom of the casing. Weakest point in the next hole section is generally the shoe. Not sure how you ensure good cement around the shoe when reversing.

Why not use a stinger to cement the shoe and then bullhead cement down the annulus to the loss zone. Run some petal baskets on the casing above the loss zone to support the cement that gets pumped in from above.
Posted by

Hari ekn

engineer

Transocean

Total Posts: 19
Jump to top of the page