APPLICATION INFORMATION
THINNERS FOR OIL-BASED DRILLING FLUIDS

OG-A 2

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Thinners for oil-based drilling fluids

Contents03	
The use of BYK additives to control yield point andgel strength in oil-based drilling fluids
04 Performance test of BYK thinners for drilling fluids
05 Rheological results
08 Static sag
09 Conclusions

03

The use of BYK additives to control yield pointand gel strength in oil-based drilling fluids
During the drilling process, fine drilling solids accumulate
and disperse in the drilling fluid. Excess solids can quicklylead to an unfavorable increase in rheological properties
such as plastic viscosity, yield point, and gel strength.

Since there is no one-size-fits-all solution, BYK offers arange of additives to meet performance and economicgoals.
BYK‘s range of non-aqueous thinner additives includes:

The use of thinners is a cost-effective way to counteract
the increase in rheological properties. As drilling
solids accumulate, thinners allow the mud to be used
for extended periods without dilution. Reducing therheological properties of the mud should also improvethe efficiency of the solids control equipment.

NoteTo ensure the best appearance
and full functionality, please
open in Adobe Acrobat.

BYK-GO 8700 – Liquid solution of sodium linear
alkylbenzene sulfonate.
BYK-GO 8701 – Polar, acidic ester of long chain alcohols.
BYK-GO 8702 – Copolymer with solids affinic groups.
BYK-A-GS 446 – Concentrated mixture of alkoxylated
resin and naphtalene sulfonic acids.

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Thinners for oil-based drilling fluids

Performance test of BYK thinners for drilling fluids
The performance of four BYK thinners for oil-baseddrilling fluids were tested at lab scale.
The drilling fluids were formulated with 10 % OCMA clay
to simulate low-gravity solids. BYK-GO 8700, BYK-GO 8701
and BYK-A-GS 446 were added at 1.0 lb/bbl andBYK-GO 8702 at 0.5 lb/bbl.
The equivalent of 14.2 laboratory barrels was preparedin a 2-gallon bucket. The lb/bbl equivalents and order ofaddition are listed below. The muds were aliquoted fromthe bucket into a mixing beaker – one mud for eachtemperature. On a multimixer (11,000 rpm), each mud wastreated with one of the thinners and mixed for 5 minutes.
The drilling fluids were then sheered at 6,000 rpm in a
Silverson mixer until they reached a temperature of 150 °F.
The performance of the four BYK thinners wasbenchmarked against lecithin.

Diesel 11.4 ppg, 75/25
Component

Amount (lb/bbl)

Diesel #2

170.0

CLAYTONE II

9.0

Lime

10.0

Emulsifier

8.0

25 % CaCl2 brine

90.0

API barite 4.1

127.0

OCMA clay

70.0
T. 01

Rheological data were measured with a viscometer at150 °F. All systems were measured before hot rolling andafter hot rolling at 250 °F for 16 hours. The muds werethen hot rolled again at 350 °F for 16 hours.
In addition, a 3-day static sag test was performed todetermine that none of the thinners adversely affected
the barite sag.

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Thinners for oil-based drilling fluids

Rheological results
The influence of the four BYK thinners on the rheologicalproperties of the drilling fluids was evaluated. A summary ofyield point, 6-rpm dial reading, and 30-minute gel strength
measured prior to heat aging is shown below. At the test
temperature of 150 °F, BYK-GO 8702 and BYK-A-GS 446
had an immediate effect on conditioning the mud within
the optimum rheological parameters.
Before heat aging, lecithin, BYK-GO 8700, and BYK-GO 8701
all had a moderate effect on the 600-rpm rheology.
BYK-GO 8702 and BYK-A-GS 446 both had an immediate
positive effect on high-end rheology.

Rheological data before hot rolling (BHR) at 150 °F
1009080
7060
50
4030
20
100Base mudYield point  

6-rpm dial reading  + Lecithin (1.0 lb/bbl)
30‘ gel strength  + BYK-GO 8700 (1.0 lb/bbl)

600-rpm dial reading+ BYK-GO 8701 (1.0 lb/bbl)+ BYK-GO 8702 (0.5 lb/bbl)+ BYK-A-GS 446 (1.0 lb/bbl)
G. 01

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Thinners for oil-based drilling fluids / Rheological results

The muds were hot rolled at 250 °F for 16 hours andtested again at 150 °F. BYK-GO 8700 and BYK-GO 8701
both performed equally as well as lecithin. At 250 °F,
BYK-GO 8702 and BYK-A-GS 446 again conditioned themud to optimal rheological ranges.
After heat aging at 250 °F, lecithin, BYK-GO 8700, andBYK-GO 8701 again all had moderate effects on 600-rpm
rheology. BYK-GO 8702 reduced the fluids 600-rpm dialreading by 11 units, while BYK-A-GS 446 reduced the fluids
600-rpm dial reading by 18 units..

Rheological data after hot rolling (AHR) at 250 °F
1009080
7060
5040
30
20100Base mudYield point  

6-rpm dial reading  + Lecithin (1.0 lb/bbl)
30‘ gel strength  + BYK-GO 8700 (1.0 lb/bbl)

600-rpm dial reading+ BYK-GO 8701 (1.0 lb/bbl)+ BYK-GO 8702 (0.5 lb/bbl)+ BYK-A-GS 446 (1.0 lb/bbl)
G. 02

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Thinners for oil-based drilling fluids / Rheological results

The drilling fluids were additionally heat-aged at 350 °F
for 16 hours. Following the same procedure, rheological
data were collected at 150 °F. After heat aging at thistemperature, BYK-GO 8700, BYK-GO 8701, BYK-GO 8702
and BYK-A-GS 446 were found to be efficient thinners,
each exhibiting temperature stability at 350 °F. The yield
point, 6-rpm rheology, and 30-minute gel strength wereconsistent for each of the products.
The results of the 600-rpm dial reading were different at350 °F. Lecithin had no positive effect on rheology, while
all four BYK thinners reduced high-end rheology. Most
notably, BYK-GO 8700, BYK-GO 8702, and BYK-A-GS-446
reduced rheology by over 11 % compared to the base mud.

Rheological data after hot rolling (AHR) at 350 °F
10090807060504030
20100Base mud
Yield point  

6-rpm dial reading  + Lecithin (1.0 lb/bbl)
30‘ gel strength  + BYK-GO 8700 (1.0 lb/bbl)

600-rpm dial reading+ BYK-GO 8701 (1.0 lb/bbl)+ BYK-GO 8702 (0.5 lb/bbl)+ BYK-A-GS 446 (1.0 lb/bbl)
G. 03

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Thinners for oil-based drilling fluids

Static sag
Weight material settling (sag) potential is an importantparameter to consider in any product that reduces rheology.
To get a complete picture of how these thinners influencesag, a 3-day static sag evaluation was performed.
Each of the fluids was transferred to aging cells and hotrolled at 150 °F for 16 hours in a roller oven. The next day,the cells were cooled and multi-mixed for 15 minutes. Aftermixing, each mud was placed in aging cells and pressurized.
The ovens were preheated to 250 °F and 350 °F.
The cells were placed in a vertical position in the two ovens.
The cells were aged at the respective temperatures for
72 hours. After static aging, the cells were removed fromthe oven and cooled with a fan undisturbed. After cooling,
the cells were depressurized and opened.

The free oil was collected with a pipette and its volume wasmeasured. This free oil was then poured into a beaker thatwas scored for 233 ml. The upper layer of the mud wasremoved from the aging cell with a spatula and transferredto the beaker until it reached 233 ml. The remaining bottom
layer in the aging cell was mixed with a spatula and a slow
speed stirrer for 10 minutes. The density of the mixed fluid
was measured using a BYK-Gardener pycnometer.
The total combined fluid was mixed and the density wasmeasured again. The sag resistance is measured bycomparing the bottom layer with the total mixed fluidusing the following equation.

Δ Bottom, ppg = density of the bottom – density of
the full mud
The smaller Δ Bottom is, the greater the sag resistanceof the fluid.
The graphs below show the sag resistance for the 3 days
at 250 °F and 350 °F. Based on these results, at 250 °F
BYK-GO 8700 improved the static sag performance of thebase mud and lecithin by 35 %. At 350 °F BYK-A-GS 446
was the best performing product reducing static sagby 35 %.

Sag resistance for 3 days

0.3

1

Δ Bottom, ppg

350 °FΔ Bottom, ppg

250 °F

0.2

0.8
0.6
0.4

0.1

0.2
00
Base mudLecithinBYK-GO 8700

BYK-GO 8701

BYK-GO 8702

BYK-A-GS 446

Base mudLecithin

BYK-GO 8700

BYK-GO 8701

BYK-GO 8702

BYK-A-GS 446
G. 04

09Thinners for oil-based drilling fluids

Conclusions
BYK‘s thinners were effective up to 350 °F. Each of them
reduced the yield point and gel strength of the muds.
Although the 6-rpm scale reading was reduced, they
had less barite sag than the base mud. BYK-GO 8702
and BYK-A-GS 446 both lowered the 600-rpm reading
immediately and it remained reduced after both hot-rollingcycles.
Since all drilling systems are different, BYK recommends
testing the product triad to find the optimum balance
between economy, performance, and treatment level.
Our experts and our application labs are here for yoursupport.

Please visit us at
Additives for Drillingfor Oilfield – BYK

06/2022
OG-A 2BYK-Chemie GmbH
Abelstraße 4546483 Wesel
GermanyTel +49 281 670-0
Fax +49 281 65735

ADD-MAX®, ADD-VANCE®, ANTI-TERRA®, AQUACER®, AQUAMAT®, AQUATIX®, BENTOLITE®, BYK®, BYK-AQUAGEL®, BYK®-DYNWET®, BYK-MAX®,
BYK®-SILCLEAN®, BYKANOL®, BYKCARE®, BYKETOL®, BYKJET®, BYKO2BLOCK®, BYKONITE®, BYKOPLAST®, BYKUMEN®, CARBOBYK®, CERACOL®,CERAFAK®, CERAFLOUR®, CERAMAT®, CERATIX®, CLAYTONE®, CLOISITE®, DISPERBYK®, DISPERPLAST®, FULACOLOR®, FULCAT®, GARAMITE®,GELWHITE®, HORDAMER®, LACTIMON®, LAPONITE®, MINERPOL®, NANOBYK®, OPTIBENT®, OPTIFLO®, OPTIGEL®, POLYAD®, PRIEX®, PURABYK®,
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and VISCOBYK® are registered trademarks of the BYK group.

info@byk.com
www.byk.com

The information herein is based on our present knowledge and experience. The information merely describes the properties of our products but noguarantee of properties in the legal sense shall be implied. We recommend testing our products as to their suitability for your envisaged purpose prior touse. No warranties of any kind, either express or implied, including warranties of merchantability or fitness for a particular purpose, are made regarding
any products mentioned herein and data or information set forth, or that such products, data or information may be used without infringing intellectual
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