NON DAMAGING DRILL FLUIDS FOR OIL AND GAS WELL

1. NON DAMAGING DRILLING
FLUIDS FOR OIL AND GAS
WELL
SUBMITTED BY
SIDHARTH GAUTAM
2014MT0226

2. CONTENTS • INTRODUCTION
• HISTORY
• MECHANISM OF FORMATION DAMAGE ATTRIBUTTED TO DRILLING
FLUID
• TO COUNTER FORMATION DAMAGE NON DAMAGING DRILL FLUID
MUST HAVE
• NDDF ADVANTAGE OVER CONVENTIONAL DRILL FLUID
• BASIC COMPOSITION OF NON DAMAGING DRILLING FLUID
• NDDF BASED ON MCC
• NDDF BASED ON SODIUM FORMATE / POTASSIUM FORMATE

3. INTRODUCTION
• Non Damaging Drilling Fluid (NDDF) is method to increase oil production by
controlling formation damage during drilling.
• NDDF was introduced in Linch field , Mehsana Asset of ONGC , in North
Cambay Basin in India.
• For a given geology , well geometry and production method , an oil well’s
productivity depends on the control over formation damage exercised
during drilling of the well.
• Formation with least damage is likely to produce more oil.
• Though all productive reservoirs are susceptible for formation damage , the
reservoir which produce by matrix mechanism like sandstone, are far more
sensitive to the effect of the well bore fluids than those produce through
fracture mechanism like limestone.

4. HISTORY
• In the early 1990s industry developed new types of fluids as drill in fluids
(DIF), to reduce drilling and completion induced damage , especially in
horizontal open hole completions.
• As standard drilling fluid , the DIFs provided lubricity , inhibition , solid
suspension and borehole stability.
• DIFs contained solid materials as bridging agents to plug the surface of a
formation matrix and as weighting material to control formation pressure.
• Experience proved to the industry that solids content of the drilling fluid
affects the performance of well.
• If drill solid could be kept to low concentration , then open hole performed
better , and if solid control was not achieved , significant formation damage
occurred.
• THUS , NON DAMAGING DRILLING FLUID was developed.

5. MECHANISM OF FORMATION DAMAGE
ATTRIBUTTED TO DRILLING FLUID
• Formation plugging by drilling fluid’s compositional solids . E.g. clay
• Formation plugging by drilled cutting
• Formation plugging by polymers’ particles
• Hydration of clay envelop around pay zone
• Change of wettability by filtrate
• Mud invasion into pay zone due to lost circulation
• Formation scale due to chemical reaction between formation fluid and mud.

6. To counter formation damage
NON DAMAGING DRILL FLUID MUST HAVE :-
• No use of non degradable compositional fine solid like clay, barite etc.
• Minimum drilled fine solid
• Effective check on polymer’s particle invasion into payzone
• Reduced filtration loss
• Lowest possible progressive gelation for minimizing whole mud invasion
during trips and gel break circulations.
• Filtrate not reacting chemically with formation fluid to form insoluble
precipitate.

7. NDDF CONTROLS FORMATION DAMAGE

8. NDDF ADVANTAGE
OVER
CONVENTIONAL DRILL FLUID
• Fine solids of conventional muds enter deep into the formation and choke
the oil passage from the reservoir to well. NDDF does not contain fine solid.
• Thixotrophy – the most needed property of drilling fluid is provided by the
additive XC polymer which is bio-degradable.
• Mud filtrate swells the clay envelops around the sand particles of the pay
zone.This obstructs the oil flow.
• NDDF generates saline inhibitive filtrate , so clay swelling does not take
place.
… Cond

9. • Properly selected sized particles of Calcium Carbonate (CaCo3) , in NDDF ,
bridge the pore throat on the formation surface to form an external filter
cake.
• An external filtercake is much easier to be removed , by drawdown , than an
internal filter cake inside the formation matrix.
• Calcium carbonate is also used to impart higher specific gravity to NDDF
(instead of barites used in conventional muds).
• Calcium Carbonate is acid soluble and can be removed later on.
• Presence of dispersant generates fine clay particle inside the formation
matrix, these particles migrates further to clog the pores.
• Since NDDF does not contain any dispersant , no clogging takes place due
to dispersion generated fines

10. BASIC COMPOSITION OF
NON DAMAGING DRILLING FLUID
15
5
10
1
0.5
0.02
COMMON SALT KCL CaCO3 PGS XC POLYMER BIOCIDE

11. NDDF BASED ON MCC
• It is meant to prevent pay zone damage.
• Non damaging and degradable constituents are used for its formulation.
• Micronized Calcium Carbonate is used as bridging material.
• The fluid is water based.
• ADVANTAGE
• Prevention of pay zone damage
• Enhancement of productivity
• APPLICATION
• Extensively used in Mumbai , Mehsana , Ahmedabad , Assam , Ankleshwar asset.
• Recommended for drilling pay zone of all development wells.

12. NDDF BASED ON SODIUM FORMATE /
POTASSIUM FORMATE
• Sodium / Potassium formate are high specific solids free fluids(sp.gravit
~1.33 with Na formate and upto 1.55 with K formate).
• They do not affect rheology adversely.
• The salts are inhibitive in nature and sustain temperature ~225 ̊C.
• ADVANTAGE
• Prevention of pay zone damage
• Enhancement of productivity
• APPLICATION
• Extensively used in Mumbai , Rajamudry asset.