Prediction Technique

Drillstring drag is the cumulative force required to move the pipe up or down inside the hole. Torque is the movement required to rotate the pipe. Drag forces usually are paralleled to the string weight measured with the string rotating but not reciprocating. Measured from the rotating string weight, the pickup drag is usually vaguely greater than the slack-off drag. The magnitudes of torque and drag are related in any particular well; high drag forces and excessive torque loads usually occur together. There are various causes for excessive torque and drag, such as tight hole conditions, keyseats, differential sticking, sloughing hole, sliding wellbore friction and cuttings buildup caused by poor hole cleaning.

With the exception of sliding friction, these causes are associated with problem conditions in the wellbore. Contrarily, in wells with great hole conditions, the primary source of torque and drag is sliding friction. Torque and drag from any source tend to be more troublesome in extended-reach directional wells. In very deep, highly deviated wells, overcoming torque and drag can be vital to the successful well completion. The capability to predict frictional loads on drillpipe has two main benefits:

1. Deep, highly deviated wells can be planned to minimize torque and drag and ensure successful drilling operations to total depth.
2. A more complete knowledge of drillstring loading allows use of improved drillstring design techniques, having considered the extra forces involved.

Both torque and drag are assumed to be caused entirely by sliding friction forces that result from contact of the drillstring with the wellbore. Two factors affect sliding wellbore friction:

1. The normal contact force
2. The coefficient of friction between the contact surfaces

The product of these two factors represents the magnitude of the sliding friction force. The normal contact force between the pipe and hole wall depends on several factors such as, the effects of gravity on the pipe, the effects of tension acting through curvatures in the wellbore and even pipe bending. The sliding friction coefficient is the ratio of the friction force to the normal contact force. This factor depends on specific contacting materials and on the degree of lubrication at various places in the wellbore. However, the oil and gas industry has made many advancements technologically speaking and quite a few models have been developed for these kind of issues.

PVI’s torque and drag model, TADPRO, is designed to help remove many of the risks of a drilling program, completions design or specific tool operations. Limits in the length of a horizontal based on specific friction factors can be determined. It can evaluate the needed weight to a liner-top packer. TADPRO can analyze forces downhole and predict rig equipment specifications for torque and hookload. The model provides both versatility and accuracy in its calculations and it integrates advanced features that make it easier for our users to use.

Imagination, Prediction and Reality

There is a joke about the human brain and it goes like this: our brain has two parts. One is the left brain and the other is in the right. The right one has nothing left and the left one has nothing right.

According to the theory of left-brain or right-brain dominance, a person who is “left-brained” is often said to be more logical, analytical, and objective, while a person who is” right-brained” is said to be more intuitive, thoughtful, and subjective.

Artists may use the right side of their brains more to maximize creativity, but if they exhaust their imagination, their art works lose their appeal.

Sometimes, we, as viewers, participate in the creative process when we enjoy a good piece of art. This can be demonstrated in our appreciation of the statue of Venus de Milo. The statue is widely renowned for the mystery of her missing arms. The missing arms do not stop people from appreciating this marvelous work of ancient Greek. People are fascinated by the missing parts and are creating their own interpretations of the possible positions of the missing arms. By imagination, everyone creates a Venus statue in their mind. Maybe that is the everlasting beauty of Venus: the incompleteness of an original work of art.

However, in the world of engineering, we strive to remove any uncertainties as much as possible. Drilling software is a tool for drilling engineers to help them predict what will happen on the rig floor and downhole.

The following graph shows the hook load prediction using TADPRO (torque and drag model).

Charts like these give drilling engineers guidelines as to what to expect during drilling operations. This way, we can see the upcoming reality with little imagination.

The Drilling Engineers’ Version of the Johari’s Window

Probably most of us have had the experience of dealing with difficult people or difficult situations at some point in our lives. I have been in situations where a person has been widely considered “difficult”. One time, I was so frustrated that I went to a bookstore trying to find a solution and I certainly found a few books that addressed the topic.

The first thing I learned from these books, which is something I should have known, is that I very likely have been a difficult person in many situations. While writing this, I am thinking of many of my friends, co-workers and clients. Their faces flash in front of my eyes as I realize that I probably have been the cause of some of their difficult situations. I am also certain that they are interested in knowing what is it that makes us tick.

Information sharing is one of the many advices that are found in these books. Sharing information is one way to strengthen relationships when dealing with perceived difficult people. The Johari’s Window is a communication tool that is used to improve understanding between individuals. This technique was created by American Psychologists Joseph Luft and Harry Ingham in 1955.

Johari Window

The four squares (windows) represent:

1. Shared: known to both you and others.
2. Hidden: Hidden information, known only to you.
3. Blind: Known to others, but not known to you.
4. Unknown: Not known to you or others.

The idea is to increase the size of the shared information window by sharing information that you previously keep to yourself and encouraging others to reciprocate. A team or group of friends that understands each other (that is, each person having a strong mutual understanding with the team) is far more effective than a team that does not understand each other (that is, a team whose members have large hidden, blind, and/or unknown areas).

Sharing information does not mean that we have to wash our dirty laundry in public. It means sharing ideas with one another about what’s important to you and them. I applied this idea to our drilling engineers and obtained this picture of a revised Johari’s Window for drilling engineering.

The Drilling Engineers' Version of Johari's Window

Through feedback, disclosure and other tools, we can develop more productive relationships and bridge the gap between the members of a drilling team. By sharing information, we get to deal with less difficult people and uncover more of our potential, which is unknown to us and others. For this reason a drilling software such as, TADPRO (Our torque and drag model) serves as a tool to enlarge the 1st window.

Antique Store and OTC

My brother, who is a civil engineer in Kentucky, came to visit us during OTC in 2013. During his stay here in Houston, we did many things together, including visiting the Offshore Technology Conference (OTC) and a local antique store.

OTC is an annual event that takes place in the month of May in Houston. As the largest oil and gas conference and exhibition in the United States, OTC attracts typically 30,000 – 50,000 visitors from around the world. The exhibition area is huge. My brother and I got tired after a couple of hours walking in one of the exhibition halls. OTC covers numerous technical areas which are totally new to us. We got lost in the aisles of booths, instruments and equipment. We felt so behind in many of the new technologies. However, we also felt that we were lucky to be part of the engineering world (drilling software for me) and that we are contributing to the big wave of technology advancement. We felt the vibe of the next generation. OTC is like a stage, where people dance with their dreams and where dreams come true.

After OTC, we visited a local antique market which had many small, individually owned shops selling items that have history. We were delighted to see many items that had quite a storied past, as the shop owners explained their history. We found an old kerosene lamp which captured a moment in our technology development.

These items are like fragments of time. Touching them allows us to travel back in time. When we are young, we spend more time dreaming, looking into the future. As we grow older, we are more occupied by things we are busy with at the present time; less time to dream, more time for memory review, perhaps.

When we are looking back at the past and forward into the future it gives pleasure to us both ways. A couple of years ago, I gave a presentation on TADPRO, our torque and drag model, to SPE Gulf Coast Section in Houston. I used two slides to summarize the history of drilling. The first one was a schematic of the drilling scene 2,000 years ago in China. The second one was a picture of an offshore platform, representing modern drilling technology. Both pictures represented the very advanced drilling technologies being used at the time. Centuries and millenniums elapsed. Our knowledge accumulation from history enables us to stand where we are.

Similarly, our drilling software development is the result of continuous engineering research and development over the past few decades. I have been fortunate to work with people with engineering and information technology backgrounds; some new and some seasoned. We, as developers are getting older, but our software stays young and robust.

Measurement of Successful Drilling Software

Being a food lover, I like to try different restaurants. A simple test to see if a restaurant is any good is to try their simple and inexpensive dish. For example, I would order a hot-and-sour soup from a Chinese restaurant. If the chef can transform simple ingredients like mushrooms, bamboo shoots, ginger, tofu to a deep and spicy marvel, then one can expect the taste and quality of the main dishes.

Similar methods can be applied to many products and services including drilling software.

To fully test a comprehensive software package is time consuming. For example, our casing wear prediction software CWPRO covers torque and drag model and casing wear accumulation for a given schedule of drilling operation. The theory part is sophisticated enough to write a PHD thesis. The graphical user interface makes the complicated prediction a very easy task. Thanks to the carefully designed navigation structure.

To evaluate CWPRO and find its user-friendliness probably takes a couple of days. But if you have a chance to use our simplest software Dr. DE – drilling engineering toolbox software, you will be amazed at how quickly those 180+ functions solve drilling problems in seconds.

It is like a good appetizer in a feast!

Drilling Software As a Renewing Process

It is said that every 7 years, we have a whole new body, because daily our old cells are dying off and being replaced with new ones. As the New York Public Library’s Science Desk Reference (Strongsong Press, 1995) notes, “There are between 50 and 70 trillion cells in the body. “ Each type of cell has its own life span. Colon cells die off after about 4 days. Red blood cells live for about 4 months, while brain cells typically last an entire lifetime. Therefore, there’s nothing special about a 7-year cycle, since cells are renewed all the time.

In a similar way, software has its own life-cycle, from 1st version to a mature product. Functions are dropped or upgraded. Window platform changes. Development tools evolve. Even developers switch. Users want better graphics with faster calculation. All these facts contribute to the ever-changing software. Our TADPRO (torque and drag model), since its 1st appearance in 2005, now is in version 7.1. If we account both major and minor version upgrades, we must have had more than 20 releases.

We have never compared how many lines of code in version 7 are still the same as those in version 1. It is definitely getting more mature as more drilling engineers start using TADPRO every year. They are the users, testers and judges. Together with them, we nurture TADPRO from a caterpillar to a beautiful butterfly.

Our body is designed to be regulated and maintained. When we don’t, we pay the price, in terms of sickness. If people do not get enough sleep, they may get accident or more serious disease; if we do not get our back well supported, we get backaches, and so on.

Engineering software like TADPRO is also a living product, demanding support from both users and developers. As drilling technologies advance and computer operating system evolves, software needs to be upgraded or turned to fit into the new environment.

Some people may think software, once purchased, works wonder forever, or think technical support, upgrade and maintenance plan is unnecessary or expensive. But think about the backaches without support or the ease of engineering work with well-supported software, you might have second thought.

Naming of Drilling Software

Almost everything on earth has a name in various languages as a point of entry. All names start in someone’s brain, the brain of someone like parents, discoverers, pioneers, inventors, and innovators. Naming is like writing a poem under constraint. You have to evoke shades of meaning in small words, paint a picture with few letters. For commercial products, naming is to link them to ideas that consumers already understand and to make the association vibrate.

Each great name like FedEx, BlackBerry, Porsche or Starbucks has its own story to tell about the new synthetic corporate language. These names are vessels capable of carrying big messages.

By the time I became a software developer and had to create names for drilling software, I was well aware that we live in a world filled with brand names. They are a part of the soundtracks of our lives. Instead of saying a cup of coffee, we say “Go Starbucks.” Mere mention of Chevron reminds us of a giant oil operator, rig floors, gas station, etc. As adman Claude Hopkins writes, the best names “are almost complete advertisements in themselves.”

When we finished our torque and drag program for oil well drilling, I was immediately aware of how hard it was to distinguish a new name from existing ones. At that time, drilling software market was filled with models like DDrag from Maurer Engineering and others. Our torque and drag model is not only for drilling operation, but also covers casing running, casing flotation, packer setting and cementing operations. To capture the broad spectrum of this new torque and drag model, we wanted a name to be more than a label, to have a compelling quality in itself and to flash a dramatically desirable picture in people’s mind. In short, we wanted a name to unlock the power of this new model.

After much brainstorming, we finally settled on TADPRO. A new name was born. I was taken by the symmetry of the name that TAD and PRO have 3 letters each. I felt that a word ending in “O” was approachable and playful. PRO projects a sense of sophistication.

On sound symbolism, when you pronounce the word TAD, it starts out crisp. Both T and D are exploded. Overall, TADPRO delivers a quick, responsive personality. Compared with DDrag, TADPRO is much faster.

Many brand names owned by corporations have gone beyond their original marketing purposes and have become bits and bytes of our modern daily language. We take an Advil and apply ChapStick.

Similarly, someday, drilling engineers, when doing torque and drag analysis for a particular operation, will simply TADPRO operation, just as we FedEx packages.

Drilling Software: A Bridge between Research Efforts and Field Executions

The term R&D or research and development refers to a specific group of activities within a business. There are 2 main goals of an R&D project: develop new products and discover/create new knowledge.

In our drilling community, we have seen many R&D projects with various sizes and duration. Petroleum engineering departments of many universities receive grants from industry and conduct specific tasks. On a big scale, joint industry projects (JIP) gather resources from different companies, both operators and service providers. I was involved in some big JIP projects such as DEA-44 (Horizontal Technology), DEA-42 (Casing Wear Technology) etc. By the way, DEA here stands for Drilling Engineering Association, not Drug Enforcement Administration. Many R&D projects produce great know-how and sometimes prototype products. However, we need a vessel to package the knowledge from these R&D efforts.

Software naturally becomes the form to hold the knowledge. With graphical user interface (GUI), it can become a powerful tool for end users, who often are not involved in the project.

An R&D project without action is incomplete. A software package serves as a bridge between the gap of research results and field executions. For example, not many people understand how the equation of force balance is used to calculate torque and drag along a drill string or casing, but most drilling engineers understand the hook load and surface torque charts. As a matter of fact, we don’t have to be able to solve numerical equations to be drilling engineers. The advanced engineering and calculation capabilities are already packed in the ready-to-use software like TADPRO (torque and drag model).

If not for exercising purpose, you probably want to ride to office than walk. You probably want to take bridge than take boat to reach the other end.

Drilling Software Solves Puzzle

I once attended a Bible study, which focused on the book of Genesis. The teacher asked: “What is the most important piece of jigsaw puzzle?”  Students started to answer “The corner ones”, “One with straight edge”. After a pause, he slowly revealed “The most important piece of jigsaw is the box top.” We all smiled when he showed us a slide of a box of puzzle with puzzle image.

He further explained that the book of Genesis is the box top of the Bible. “Genesis maps out all the happenings of the entire Bible.” He said.

Many of us played with puzzles ourselves or with our children. The finished artwork bears no resemblance to the hundreds of pieces of colored cardboards in the box that initially greeted us. Although the individual elements remain the same, and do not reveal much information, the complete work allows us to see the whole picture.

In a similar manner, drilling engineers are constantly putting together the pieces of procedure, equipment, instrument readings from rig floor, and their own calculations. Our job is to fit them into the right places. This way, we can understand why certain drilling parameters change, why problems occur or what our observation mean.

The beauty of drilling software such as TADPRO (torque and drag) is its ability to put pieces of information including ROP, RPM and WOB all together to solve the puzzle. The integration of operation parameters, wellbore trajectory and advanced mathematics model produces more meaningful results.  Think of TADPRO as your box top!

Everyone including drilling engineer seems to be busier than before – There are always more wells to be drilled, more projects to be managed, more well planning to be done and reports to be run. Let us face it: you and I are not supermen or ironmen. We are just normal John and Joe, facing the increasing demanding.

Any help would be helpful. Imagine an assistant, who could be on-call 24/7! And she does not charge overtime or complain about tasks. One might think this kind of helper is a far-fetched idea. But what is in my mind is an assistant you can actually own and this assistant is most likely a super model: drilling engineering model.

All of us hate to do repeated tasks, and that is why we invented dish washer and vacuum cleaner. From abacus, to calculator, to computer, we calculate more and faster. It might be fun to find the greatest common divisor in 3rd grade, but hand calculation of a buoyant weight of pipe in mud is more of a tedious step than an exciting destination. We have important technical decisions to be made in office and on rig floor.

That is why drilling engineering software such as PVI’s TADPRO (torque and drag model) comes handy. It frees us from repeated manual calculation and errors associated. These drilling models do not discriminate vertical, deviated, horizontal or ERD wells. Provided with proper input data, these model assistants perform analysis, run reports, show animation within a few seconds. If you are not sure about certain variable such as friction factor in open hole sections, they like many attentive helpers, even give you sensitivity study to show you the best and worst scenarios.

Sometimes, these models are just like robots, receiving orders and performing tasks. Other times, they give you crucial advices and identify potential problems, such as helical buckling or excessive downhole pressure. They are like a senior consultant who is amiable and does not charge premium.

These models are strictly trained to be friendly. They do not care much if you give them a job after 5pm or in weekends. They are very tolerant if you accidently key in the wrong data. They do not give you an eye. Instead, they kindly remind you of the error and even suggest you the correct input in many cases.

Did I mention that these models are very pretty? Their faces (what we call interface) are carefully designed so that users will not get lost and interaction creates pleasant experience.

Drilling is tough, find good software - your hot model.