Drilling Mud Performance in Hole Cleaning of Well PRP-620A in Angola

62 Pages·2017·2.59 MB·English

by  Mario Fayenda

University of Miskolc
Faculty of Earth Science and Engineering
Department of Petroleum Engineering

Title

Drilling Mud Performance in Hole Cleaning of Well PRP-620A in
Angola

Author's name: Mário Camove Jacinto Fayenda
Department supervisor: Szabó Tibor, PhD

Miskolc, November 2017
MISKOLCI EGYETEM UNIVERSITY OF MISKOLC
Műszaki Földtudományi Kar Faculty of Earth Science & Engineering
KŐOLAJ ÉS FÖLDGÁZ INTÉZET PETROLEUM AND NATURAL GAS INSTITUTE

————————————————————————————————————————————————————————————————————————————————————————————————
 : H-3515 Miskolc-Egyetemváros, Hungary  : (36) (46) 565-078
e-mail: [email protected]

BS Thesis Assignment
for
Mário Camove Jacinto Fayenda

Title of Thesis:
Drilling Mud Performance in Hole Cleaning of Well PRP-620A in
Angola

Main tasks:
Introduction of the used drilling fluid systems
The main parameters affecting on hole cleaning
Analyse the hole cleaning efficiency and the hydraulics of the given well
Conclusions, recommendations

Faculty Advisor: Tibor Szabó, PhD
Deadline of submission. 27 November 2017.

Zoltán Turzó, PhD
Head of Institute
Institutional verification paper for thesis submit
for BSc students in specialization oil and natural gas
Student name: Mário Camove Jacinto Fayenda
Neptun-code: BS92FU
Title of thesis: Drilling Mud Performance in hole cleaning of well PRP-620A in
Angola
Originality statement
I, Mário Camove Jacinto Fayenda hereby declare and certify with my signature under my
criminal and disciplinary responsibility as the student of the Faculty of Earth Science and
Engineering at the University of Miskolc that this thesis was my own work. I complied
with the regulations of the Act LXXVI of 1999 on copyrights and with the requirements of
thesis writing in the University. In the thesis only the references listed in the literature
were used. Literal or reworded quotations have clearly been marked as references. I
declare that the electronically uploaded and paper-based documents are concurrent. By
signing this declaration, I acknowledge that the University of Miskolc refuses to accept the
thesis and may initiate a disciplinary procedure against me if I am not the sole creator or
an infringement of copyright in the thesis can be proved. Refusing to accept a thesis and
initiating a disciplinary procedure is without prejudice to any other (civil, legal, criminal,
legal) consequences of copyright infringement.
Miskolc, 27 November 2017
Student signature
Statement of the Department Supervisor
I, the undersigned Tibor Szabó, agree / disagree with the submitting of the thesis.1)
Miskolc 27 November 2017
-----------------------------
Signature of the supervisor
The thesis is submitted
Miskolc, 04 December 2017

Administration of the Petroleum
and Natural Gas Institute

1 The unchosen part should be marked with strikethrough. The thesis can be submitted with the disapproval
of the Supervisor or the Industrial Advisor.
This verification paper with the necessary signatures must be attached in the original thesis after the thesis
assignment.
2 This paragraph can be erased in the absence of an Industrial Advisor.
Preface
With the enclosure of this thesis comes to an end my bachelor program in the University
of Miskolc. It leads to a BSc degree in Oil and Gas Engineering.
I am truly grateful to my supervisor Szabó Tibor who gave me the opportunity to work on
this stipendium thesis work. His great support and vision throughout the thesis period I
highly appreciate.
Moreover, I appreciate his openness toward me, I was welcomed at any time of the day
and days of the week, I thank his patience and availability always willing to give an advice
and tell me the next step forward.
Honestly, I wish this work could continue in some other manner because in this ending
semester I have become quite an expert in this part of drilling Engineering which is really
important to the Oil and Gas industry.
And of course I am not thinking of ending this section without thanking my dearest
girlfriend Rosaria Augusto and family specially my parents for their support and
encouragement.
Last but not least to all my friends and my 4 course mates, my heart says thank you for
being more than colleagues but brothers throughout these years.

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TABLE OF FIGURES
1. Figure 1…………………………………………………page 26
2. Figure 2………………………………………………….page 27
3. Figure 3………………………………………………….page 28
4. Figure 4…………………………………………….……page 29
5. Figure 5………………………………………………….page 36
6. Figure 6…………………………………………….……page 37
7. Figure 7………………………………………………….page 45

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ABBREVIATIONS
ECD Equivalent circulation density
API American Petroleum Institute
CCI Carrying capacity index
TR Transport Ratio
ROP Rate of penetration
TI Transport index
RF Rheology factor
AF Angle factor
PV Plastic viscosity (cp)
YP Yield point (2/100 lb ft )
Cc Cuttings concentration
v Velocity
A Area (2 ft)
IF Jet impact force
WBM Water based Mud
OBM Oil based Mud
LSRV Low shear rate viscosity
POM Polyoxymethylene
LCM Lost Circulation Material
BHHP Bit Hydraulic Horse Power
BHA-OH Bottom Hole Assembly-Open Hole

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CONTENT TABLE

1. INTRODUCTION ..................................................................................................... 8
2. DRILLING FLUIDS ................................................................................................. 9
2.1 Mud Types ......................................................................................................... 9
2.2 Basic Mud Ingredients ........................................................................................ 9
2.3 Clear Fluids ...................................................................................................... 10
2.4 Mud (Slurries) .................................................................................................. 10
2.5 Factors Affecting Drilling Mud Selection ......................................................... 12
2.6 Properties of the Drilling Mud .......................................................................... 13
3. FUNCTIONS OF THE DRILLING MUD ............................................................... 15
3.1 Remove Cuttings from the Well ........................................................................ 15
3.2 Controlling Formation Pressures ....................................................................... 17
3.3 Suspend and Release Cuttings ........................................................................... 18
3.4 Seal Permeable Formations ............................................................................... 19
3.5 Maintain Wellbore Stability .............................................................................. 19
3.6 Minimize Formation Damage ........................................................................... 21
3.7 Cool, Lubricate and Support the Bit and Drilling Assembly .............................. 21
3.8 Transmit Hydraulic Energy to Tools and Bit ..................................................... 22
3.9 Ensure Adequate Formation Evaluation ............................................................ 23
3.10 Control Corrosion ............................................................................................. 23
3.11 Facilitate Cementing and Completion ............................................................... 24
3.12 Minimize Impact on the Environment ............................................................... 25
4. HOLE CLEANING ................................................................................................. 26
5. GUIDELINES FOR EFFICIENT HOLE CLEANING ............................................. 32
6. Hydraulics optimization on Well PRP-620A ............................................................ 37
7. Well PRP-620A ....................................................................................................... 45
8. Main issues on well PRP-620A report ...................................................................... 46
9. WELL ISSUE ANALYSIS ...................................................................................... 47
9.1 A SET OF BEST PRACTICES RECOMMENDED ......................................... 47
10. CONCLUSION .................................................................................................... 49
10.1 Further recommendations ................................................................................. 50
References ...................................................................................................................... 51
Appendices ..................................................................................................................... 52

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1. INTRODUCTION

Due to world’s energy demand increment, ultra deep, extended reach, and highly deviated
wells are being drilled in order to correspond this demand. Yet, one of the major
difficulties in highly deviated and extended reach wells is the issue of hole cleaning during
the drilling operation.
In Angola 18 of the 31 blocks are in the deep and ultra-deep waters of the Congo basin,
and the blocks 19 and 24 in the deep waters of the Kwanza and Benguela basins.
This circumstantial working condition highlights the demands for good and efficient hole
cleaning procedures. Therefore the key to a successful drilling operation relies upon
integrating optimum drilling fluid properties with best drilling practices.
Drilling fluid or MUD is a mixture of liquids and chemicals that allow the drilling and
completion of a well. Drilling mud performs numerous functions that help make this
possible.
In this present thesis a special analysis will be taken on the efficiency of the drilling fluids
in hole cleaning services of the Angolan wells in particular well PRP-620A, operated by
Total.

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2. DRILLING FLUIDS

According to the Schlumberger glossary we can define drilling fluid as being any of a
number of liquid and gaseous fluids and mixture of fluids and solids (as solid suspensions,
mixtures and emulsions of liquids, gases and solids) used in operations to drill boreholes
into the earth. In general the nickname drilling mud is more common although some prefer
to reserve the term drilling fluid to more sophisticated and well-defined Muds.
The classification of drilling fluids has been attempted in many ways, often producing
more confusion then insight, therefore in this record we will have a much shorter and clear
view over this very important fluids to the oil industry.
2.1 Mud Types

Many different types of drilling fluid systems (muds) are used in drilling operations. Basic
drilling fluid systems are usually converted to more complex systems as a well is
deepened and the wellbore temperature and/or pressure increases.
There are several types of drilling mud according [13] to need, they are:
 Gases (Air, Gas, N2)
 Clean Fluids (Water, Brine, Oil)
 Mud (Slurries)
-WBM
-Invert Emulsions (OBM, ACCOLADE, etc)
2.2 Basic Mud Ingredients

Due to its numerous functions [13] Drilling mud is generally made of:
 Viscosifiers (+ suspension agents)
 Thinners (+ deflocculants)
 Filtration Control / Wall Cake Builders
 Control clay swelling, eg KCl, Glycol
 pH control (acid / alkali)

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 Weighting agents, eg. Barite, salts etc.

2.3 Clear Fluids

Clear fluids (no suspended solids) drill faster than mud (contain suspended solids)
 Fresh water used onshore
 Seawater used offshore
 Brines used for high density & to inhibit clay swelling
2.4 Mud (Slurries)

Mud consists of base fluid + suspended solids
When the base Fluid is water the Mud is called Water based Mud (WBM)
When the base fluid is oil the Mud is called Oil Based Mud (OBM) this mud can
be made of diesel or mineral oil synthetic (Ester / Olefin)

 Water-based Mud
In this kind of Mud water is the continuous or external phase and the products are soluble
or activated by the water. The water may come from the sea, freshwater or brackish water
depending on the availability and the system to e used. Vertical well can try water-based
mud, but it is less economical than horizontal wells for extracting shale gas.
There are two categories of water-based fluids
 Non-dispersed or floccullated fluids
 Dispersed or deflocculated fluids
According to the literature [13] “Dispersed” means that thinners are added to scatter
chemically the bentonite (clay) and reactive drilling solids to prevent them from building
up. In this kind of mechanism, drilling fluids penetrates the cuttings and dissolve it into
solution, this mechanism can be efficient for cleaning some hole sections.
“Non-Dispersed” means that the clay particles are not free to find their own dispersed
equilibrium in the water phase. In this system the entire cuttings must be removed from

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