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Fluid Loss
09 December 2013
Is there any detriment to having too low a fluid loss apart from the financial cost of maintaining filtration control additives in the mud system?
9 answer(s)
(retired) Well Fluids Team leader
SPREAD Associates
Total Posts: 57
Join Date: 14/06/06

Mohammad , 

Sorry I tried to answer the original question first!!

There should be little if any fluid loss into shale. Otherwise slates would not be much use on a roof. If you run a log you should not see a filter cake against a shale formation.

What does occur is a type of osmosis called pore pressure penetration.   As we are drilling over balanced the excessive hydrostatic will act as a driving force pushing ions into the formations and increasing the near well bore pressure. The drilled formations will increase in pressure due to PPP and there will be no overbalance allowing shales to fail with drill pipe movement. At the same time K+ ions will be push into the shale pores.

K+ ions can reduce shale swelling leading (they may also increase permeability) by increasing shale strength in certain clay formations such as smectite and illite.  

But Inhibitive fluids can also promote pressure invasion and borehole instability.

So there are two opposing forces the inhibition from K+ and PPP lead to absence of an overbalance.

Field and laboratory experience suggest that the benefit of inhibition (K+) outweighs the drawback of pressure invasion. However, PPP does suggest that open hole time should be limited with K+ based systems otherwise as there is no effective overbalance borehole instability can occur resulting in cavings and the loss of many long deviated shale sections drilled with KCl systems.   

(retired) Well Fluids Team leader
SPREAD Associates
Total Posts: 57
Join Date: 14/06/06

In WBM fluid loss control requirements  based on offset data will give you an idea of the maximum fluid loss you can run without increasing the risk of getting stuck. For non reservoir WBM I'd be looking at less than 8mls for room temperature fluid loss.  

For formation damage prevention in both WBM and OBM the key issue is prevention of spurt loss.
Secondly reducing formation damage will be helped by reducing fluid loss to as low as possible. 
Fluid loss downhole and the impact on stuck pipe risk is influenced by both pressure and temperature thus HTHP testing is a priority for OBM and HTHP water based mud usage. Perform HTHP fluid loss at a temperature slight above the well bottom hole static.  temperature.  For OBM   you should never observe water in the filtrate of a HTHP fluid loss test. Stop and fix immediately.  
In the eighties I spent many years developing and testing a number of HTHP water based mud. Limited chemicals are available that will work in this environment. Getting a stable system with a HTHP below 20mls and an acceptable filter cake thickness are the main drawback.  In addition OBM cuttings to shore etc. was not developed at this time.  HTHP muds are expensive and challenging to run.  I expect everyone will run OBM in the HTHP wells these days.  

National Iranian Oil Company
Total Posts: 1
Join Date: 15/05/15
maybe sometimes it is not the worst idea to let mud filtrate loss increase when there is active shale (shales that have been in contact with wtr).in this case salt ions (especially K+) can penetrate into the shale lattice and reduce swelling hence assist wellbore stability.
Associate VP
Gujarat State Petroleum Co
Total Posts: 1
Join Date: 17/09/13
1. Formation damage due to flid loss additive
2. Low ROP
senior drilling engineer
Kuwait Energy
Total Posts: 14
Join Date: 29/11/13
I would like to add that there is adifference between the following :
1. Water Loss : this is water filterate and it should be less than 5 against shale and pay zone and HPHT less than 10.
2. Fluid loss : is lossing the complete mud within the formation, fluid loss is required in surface sand hole to be not controlled to build a good cake.
it is not recommended to control water loss in surface holes.
but going deeper against shale it is recommended to prevent water be in contact with the shale parts.
Drilling Fluids Consultant
SPREAD Associates
Total Posts: 3
Join Date: 21/01/11
In WBM no. Have heard of reduced ROPs in OBM, but never experienced this personally. It was briefly fashionable to run 'relaxed filtrate' OBM's to enhance ROP, but by all accounts it was disastrous (hole stability issues). However, having a very tight filtrate is often unnecessary, depending on formation drilled. Sandstone (esp. depleted and reservoir sands) usually necessitates a having a low fluid loss. Not so critical in most non-porous formations or salt, especially in larger hole sizes.
Drilling Fluids Superintendent
SPREAD Associates
Total Posts: 14
Join Date: 09/03/09
Having a very tightly controlled fluid loss can, in some instances, reduce penetration rate as it can affect  the chip hold-down pressure.
(retired) Well Fluids Team leader
SPREAD Associates
Total Posts: 57
Join Date: 14/06/06
Stephen, Can't think of any in normal drilling application. Sometimes you need some invasion in sandstone reservoirs for logs that are looking at K+ nuclei or dosed tracers. 
Drilling Ops Engr
Sterling Oil Exploration & Energy Co
Total Posts: 1
Join Date: 03/10/13
formation damage if we are in payzone,
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