ABSTRACT
Drilling is a process that involves the procurement of natural resources such as oil and gas which
holds prime importance in today’s world, Drilling practices abounds with a number of
complications and an efficient way of dealing with such problems is key to the continuity of the
process.
One of such problems is stuck pipe, stuck pipe is a common problem in the industry and it
accounts for major rig time loss known as Non Productive Time (NPT) and also accounts for
billions of dollars wasted annually in the petroleum industry.
The purpose of this project to implement a powerful machine learning tool known as the
Artificial Neural Network in the prediction of stuck pipe using Niger Delta fields as a case study,
The ANN is a Matlab built in function and computational system inspired by the structure,
processing method and learning ability of the human brain.
The ANN has the ability to take multiple inputs ( plastic viscosity, yield point and gel strength at
10 seconds and 10 minutes), a target ( mud weight ) to produce a single output which is the
prediction of the occurrence of stuck pipe. This was successfully carried in this research study. It
is therefore shown in this study that the ANN can be successfully used to predict the occurrence
of stuck pipe. Thus, they can be utilized with real-time data representing the results on a log
viewer which can help reduce the occurrence of getting stuck while drilling and all the
complications that comes with this occurrence.
vi
TABLES OF CONTENT
TITLE PAGE………………………………………………………………………………………………………………….. i
CERTIFICATION ………………………………………………………………………………………………………….. ii
DEDICATION……………………………………………………………………………………………………………….iii
ACKNOWLEDGEMENT……………………………………………………………………………………………….iii
ABSTRACT…………………………………………………………………………………………………………………… v
LIST OF FIGURES ……………………………………………………………………………………………………….. ix
LIST OF TABLES………………………………………………………………………………………………………….. x
CHAPTER ONE…………………………………………………………………………………………………………….. 1
1.0 INTRODUCTION……………………………………………………………………………………………… 1
1.1.1 Mechanical sticking: ……………………………………………………………………………………. 2
1.1.2 Differential sticking …………………………………………………………………………………….. 3
1.1.3 Freeing stuck pipe ……………………………………………………………………………………….. 6
1.2 Background of Study………………………………………………………………………………………….. 7
1.3 Aims and Objective……………………………………………………………………………………………. 8
1.5 Scope of Study ………………………………………………………………………………………………… 10
1.6 Justification …………………………………………………………………………………………………….. 10
1.7 Materials and Methodology ………………………………………………………………………………. 10
CHAPTER TWO ………………………………………………………………………………………………………….. 12
2.0 LITERATUE REVIEW AND THEORITICAL FRAMEWORK …………………………… 12
vii
2.1 Artificial Neural Network …………………………………………………………………………………. 12
2.2 Literature Review…………………………………………………………………………………………….. 16
2.2.1 Stuck pipe prediction using ANN………………………………………………………………… 16
2.2.2 Analysis and prevention of stuck pipe………………………………………………………….. 17
2.2.3 Stuck pipe prediction using other tools …………………………………………………………. 19
2.2.4 Stuck Pipe in Niger Delta ……………………………………………………………………………. 20
CHAPTER THREE ………………………………………………………………………………………………………. 21
3.0 MATERIALS AND METHODOLOGY …………………………………………………………….. 21
3.1 Introduction …………………………………………………………………………………………………. 21
3.2 Data Acquisition…………………………………………………………………………………………… 21
3.3 Selection of the parameters…………………………………………………………………………….. 22
3.4 ANN Training………………………………………………………………………………………………. 24
CHAPTER FOUR…………………………………………………………………………………………………………. 27
4.0 RESULT AND DISCUSSION…………………………………………………………………………… 27
4.1 Experimental Data ………………………………………………………………………………………… 28
CHAPTER FIVE ………………………………………………………………………………………………………….. 36
5.0 CONCLUSION AND RECOMMENDATION……………………………………………………. 36
5.1 Conclusion……………………………………………………………………………………………………….. 36
5.2 Recommendation………………………………………………………………………………………………. 36
STUCK PIPE PREDICION SIMULATIONAND PREDICTION CODES USING ANN…… 41
viii
APPENDIX 2……………………………………………………………………………………………………………….. 53
STUCK PIPE PREDICION EXPRIMENTAL GRAPHS FOR INPUT AND OUTPUT …….. 53
ix
LIST OF FIGURES
Figure 1: Cross sectional view of differentially stuck pipe (http://www.drillingformulas.com). ……………..4
Figure 2: Top view of a differentially stuck pipe (1997 Drillers Stuck pipe Handbook) ………………………..4
Figure 3 : schematic of the ANN system ……………………………………………………………………………………….14
Figure 4 : Workspace for inputting time series……………………………………………………………………………….24
Figure 5: Interface for making network architecture choices. …………………………………………………………..25
Figure 6: Interface for choosing training algorithm…………………………………………………………………………25
Figure 7: Interface for choosing validation and testing data……………………………………………………………..26
Figure 8: Graph of Experimental value of plastic viscosity versus number of runs……………………………..29
Figure 9: Graph of experimental value of yield point versus number of runs……………………………………..30
Figure 10:Graph of experimntal value of gel (10 secs) versus number of runs……………………………………30
Figure 11:Graph of experimental value of gel (10 mins) versus number of runs…………………………………31
Figure 12: Graph of experimental value of mud weight versus number of runs ………………………………….32
Figure 13: A graph showing variation between the experimented and simulated value for NARX………..33
Figure 14: A graph showing variation between the experimented and predicted value for NARX ………..33
Figure 15: A graph showing variation between the experimented and simulated value for NAR…………..34
Figure 16: A graph showing variation between the experimented and simulated value for NAR…………..34
Figure 17: A graph showing variation between the experimented and simulated value for NOI……………35
x
LIST OF TABLES
Table 2.1: Input and output data for parameter selection………………………………..22
Table 4.1: MSE for Levenberg Marquadt………………………………………………..27
Table 4.2: MSE for Bayesian Regularization ……………………………………………27
Table 4.3: MSE for scaled Conjugate Gradient…………………………………………..28
1
CHAPTER ONE
1.0 INTRODUCTION
Over several years the petroleum industry has been facing challenges associated with stuck pipe.
Stuck pipe has caused a major drilling cost for the drilling industry worldwide and various cost
estimates carried out have indicated that the cost of fixing stuck pipe issues exceeds $250 million
per year (Bradley et al., 1991).
Problems of stuck pipe can range from minor inconveniences to increase in drilling cost up to
major complications which will lead to altered drilling due to the inability to drill when this
occurs resulting in major time loss.
A major key to the reduction of this phenomenon is the ability to correctly or even better,
accurately predict the occurrence of stuck pipe.
Generally, stuck pipe is described as any restriction of upward or downward movement of drill
string and/or pipe rotation and leads to a situation where the pipe cannot be freed from the hole
without damaging the pipe, and without exceeding the drill rigs maximum allowed hook load.
The portion of the drill string that cannot be rotated or moved vertically is known as the stuck
pipe.
There are several causes of stuck pipe which include poor hole cleaning, key sitting, collapsed
casing, junk, cement related problems, mobile formation, geo-pressured formation, fractured
formation. However, the causes of stuck pipe can be classified under two broad categories which
are mechanical and differential sticking.
2
1.1.1 Mechanical sticking:
This is the limiting or prevention of motion of the drill string by anything other than differential
pressure sticking. According to drillers stuck pipe handbook (1997) by Schlumberger,
Mechanical Sticking can be caused by the following:
1. Inadequate hole cleaning
2. Formation instability (brittle, sloughing, or swelling shales)
3. Key seating
4. Under gauge hole
5. Tectonically stressed formations
6. Plastic or mobile formations
7. Under pressured formations
8. Junk
9. Ledges and doglegs
10. Collapsed casing/tubing
11. Unconsolidated formations
12. Large boulders falling into the hole
3
13. Running large gauge tools
14. Cement blocks
15. Green cement
However, most cases of mechanical sticking can be avoided by proper well planning, optimal
mud design and right directional planning.
1.1.2 Differential sticking
Differential pipe sticking is one of the stuck pipe mechanisms that have had a major impact on
drilling efficiency and well costs (Adams, 1977; Weakley, 1990; Wisnie and Zheiwei, 1994); it
is in most drilling organization, the greatest drilling problem worldwide in terms of time and
financial cost.
This is a condition whereby the drill string cannot be moved (rotate or reciprocated) along the
axis of the wellbore. Differential sticking occurs when high contact force caused by low
reservoir pressure, high wellbore pressures, or both, are exerted over a sufficiently large area of
the drill string. It is important to note that the sticking force is a product of the differential
pressure between the wellbore and the reservoir and the area that the differential pressure is
acting upon, this means that a relative low differential pressure (δp) applied over a large working
area can be effective in sticking the pipe as can a high differential pressure applied over a small
area.
4
Figure 1: Cross sectional view of differentially stuck pipe (http://www.drillingformulas.com).
Figure 2: Top view of a differentially stuck pipe (1997 Drillers Stuck pipe Handbook)
The figures simply means that there is a pressure difference between the mud and the formation
which can cause the drill collar and the drill pipe to be pushed against the borehole wall therefore
it becomes impossible for the draw work to pull the pipe free.
5
Differential pipe sticking occurs when a part of the drill string, casing, or logging tool becomes
embedded in a mud solids filter cake and is held there by a significant amount of differential
pressure. This differential pressure is the pressure difference between the hydrostatic pressure of
mud and the formation pore pressure. Usually, because of the excessive differential pressure, the
sticking takes place across porous and permeable formations such as sandstone or limestone,
where a mud filter cake builds up during drilling. It does not occur in very low permeability
formations such as shale’s, where mud filter cakes normally do not form. Although these
symptoms are similar to Key Seat sticking, they usually occur under different drilling conditions.
Significant mud overbalance, as well as an exposed permeable section, must also exist for
differential sticking to occur. It is clear that as many reservoirs become depleted, a significant
number of wells will be drilled with high overbalance pressures, thereby maintaining the
industry’s concerns over differential sticking (Miri et al., 2007). The likelihood of differential
sticking is increased further with the length of the permeable section that is open to the drilling
fluid. The continued trend towards extended reach and horizontal drilling means that increasing
lengths of permeable formations are exposed. Clearly, the nature of the rock formations
encountered certainly cannot be altered. Therefore, if those formations carry a high risk of
differential sticking, this has to be accepted. Also, high overbalance pressures may be
unavoidable if they are needed to maintain well control or wellbore stability in other parts of the
open hole section. However, mud composition and properties can be modified, within limits, in
the prevention of differential sticking.
6
Differential pipe sticking problems generally result in the significant amount of downtime and
remedial costs and well cost overruns and time overruns as a non-productive time in terms of
loss of rig days either due to stopping of drilling operations or in an attempt to free the stuck pipe
1.1.3 Freeing stuck pipe
Several approaches have been developed to avoid or prevent stuck pipe, proactive approaches
which utilize effective techniques to predict or detect stuck pipe before it occurs one of which is
discussed in this literature. However it is important to know measures taken to free stuck pipe
when stuck pipe incidences occur i.e. the actions made after the pipe gets stuck.
Pipe sticking is said to be a very bad surprise when drilling because once it occurs it
automatically alters every operation and it is impossible to estimate how long it will take to pull
out free, it can last for seconds, hours, days or even months and can even cause abandonments
depending on the magnitude.
Usually when the pipe suddenly gets stuck, the first action is how to get it free as quickly as
possible. Regardless of the cause of sticking, the most common action in drilling industry to free
the pipe is to work it out by firing the jars, which are parts of drilling assembly. Jars exert huge
amount of energy on drill string, which can be transferred to an impact force that may be able to
free the pipe. Depending on the cause of the sticking, jars may be applied downwards or
upwards. However, Jars sometimes are ineffective especially when they are placed below stuck
point, which can be due to poor estimation of stuck zone or lacking of proper field experience. In
addition the hydrostatic pressure can also be reduced by pumping low weight mud/pill, ensuring
that the overall hydrostatic pressure is still able to control reservoir fluid from accidentally
7
entering the wellbore. Continue jarring down with maximum trip load and apply torque into drill
string.
However if all attempts to free the stuck pipe prove abortive, the next option is to retrieve he
stuck pipe using special tools designed for this purpose, this tools are known as Fishing
assemblies, they are a wide variety of equipment and tools used in retrieving down hole
equipment, BHAs that get lost in the hole.
Depending on their functionality and the requirement in hand, we can classify them as the
following:
External Catch Fishing tools
Internal Catch Fishing tools
Junk Catch Fishing tools
Milling and Cutting tools
Each of the above stated set of tools has their own specifications and are very handy in fishing
operations.
1.2 Background of Study
Since the commencement of drilling operation in the petroleum industries stuck pipe has been a
common problem with tremendous impact on drilling efficiency and cost among other problems.
Industry statistics gathered since 1989 show the relative cost of nonproductive time. Stuck pipe
is still the drilling industry’s most costly unscheduled event (SPE, 2013). This occurrence can be
said to be caused by different conditions, which have been narrowed down to two categories;
mechanical and differential sticking and has been said to have cost the petroleum industry
millions of dollars annually.
8
Different approaches have been adopted in an attempt to reduce the cost and rig time wasted on
pipe sticking by predicting the occurrence, analyzing the causes, methods to prevent the
occurrence, immediate actions to carry out when differential pipe sticking occurs and even
methods of predicting the occurrence of stuck pipe.
Miri et al., (2007) implemented the Artificial Neural Network (ANN) to predict pipe sticking in
Iranian Fields, Mustafa Moradi Nehzad et al., (2012), also did a study on a Maroon field were
stuck pipe was predicted using the ANN.
Stuck pipe prediction approaches have also been carried out for the Niger Delta fields by M.A
Magaji et al., (Shell Petroleum Development Company, 2002), their paper reviewed the
implementation of the stuck pipe factor prediction tool which was developed based on prevailing
occurrence and existing data, however the tool can only be used to predict the inherent risk of
getting stuck in well planning and designing stage.
Therefore, this research study is aimed at predicting stuck pipe using the using the Niger Delta
Field as a case study.
1.3 Aims and Objective
This aim of this research project is
To predict occurrence of stuck pipe in the Niger Delta by examining, analyzing
drilling parameters gotten from some daily drilling reports within the Niger Delta
fields using the Artificial Neural Network.
9
To achieve this aim, my objectives include to:
Identify, study, analyze and understand the causes the causes of stuck pipe
Analyze the difference between drilling parameters of stuck and non- stuck wells
to enable proper prediction of probability of getting stuck
Implement the ANN in predicting pipe sticking in Niger Delta fields.
1.4 Problem Statement
The purpose of his project is to utilize a powerful machine learning tool, i.e. the ANN to predict
the occurrence of stuck pipe which has been a problem in the petroleum industry since the
inception of drilling and has led to a lot of cost due fishing operation and time lost in addressing
stuck pipe incidences.
This research intends to:
analyze the importance of each mud parameter to determine their contribution to pipe
sticking to aid in stuck pipe prediction
predict the occurrence of stuck pipe to eschew the risk associated with drilling and
excessive drilling.
avoid or reduce to the barest minimum the amount of money used in drilling.
avoid cost spent on fishing lost down hole tools.
10
1.5 Scope of Study
There are several causes of pipe sticking, however this project will be narrowed down to
differential sticking, and how ANN can be used to predict its occurrence using data acquired
from Niger Delta Fields.
1.6 Justification
The technique of stuck pipe prediction using ANN can be utilized for calculating the risk of
stuck pipe either mechanically or differentially before the operation. It is therefore very essential
to predict the occurrence of getting stuck because if the drilling personnel know that the
parameters used for drilling can cause pipes to get stuck, the parameters will be adjusted and that
will result in a smooth operation.
In the comparison between wells that were drilled successfully without getting stuck and wells
that had pipe sticking problem, it was clear that some parameters clearly different, therefore this
research entails analyzing those differences and using them to predict the occurrence of stuck
pipe.
This project will help the petroleum industry and the economy to reduce the amount spent on the
already very expensive drilling operations. This will be done by reducing the need for retrieving
lost down hole tools to due to stuck pipe which is a very expensive operation known as fishing,
and will also reduce the Non Productive Time (NPT) spent of suck pipe problems.
1.7 Materials and Methodology
For the purpose of this project, a reliable approach for prediction of pipe sticking which is based
on ANN is presented. In this method, our system possesses multiple inputs which include the
plastic viscosity of the mud, the yield point, the mud weight and the gel strength, etc., and one
output, which is the probability of pipe sticking.
11
Furthermore to aid this research, raw data, resources from oil companies which have had
incidences of stuck pipe and successful drilling (non- stuck pipe) operations will be widely
consulted alongside materials from the internet and the library.
The materials for my research will majorly be raw data from daily drilling reports from oil
companies comprising of the reports of stuck and non-stuck pipe. Other sources for my research
will include text books, articles written by scholars on the field of study, materials from the
internet and the library material shall also be widely utilized.
DISCLAIMER: All project works, files and documents posted on this website, eProjectTopics.com are the property/copyright of their respective owners. They are for research reference/guidance purposes only and some of the works may be crowd-sourced. Please don’t submit someone’s work as your own to avoid plagiarism and its consequences. Use it as a reference/citation/guidance purpose only and not copy the work word for word (verbatim). The paper should be used as a guide or framework for your own paper. The contents of this paper should be able to help you in generating new ideas and thoughts for your own study. eProjectTopics.com is a repository of research works where works are uploaded for research guidance. Our aim of providing this work is to help you eradicate the stress of going from one school library to another in search of research materials. This is a legal service because all tertiary institutions permit their students to read previous works, projects, books, articles, journals or papers while developing their own works. This is where the need for literature review comes in. “What a good artist understands is that nothing comes from nowhere. The paid subscription on eProjectTopics.com is a means by which the website is maintained to support Open Education. If you see your work posted here by any means, and you want it to be removed/credited, please contact us with the web address link to the work. We will reply to and honour every request. Please notice it may take up to 24 – 48 hours to process your request.
