what you’ll need: • 1cleardrinkingglassorplasticcup• 59ml(1/4cup)honey• 118ml(1/2cup)water• Afewdropsofcookingoil

1. Pourthehoneyintotheglass.

2. Next,pourthewaterintotheglass.

3. Finally,pourafewdropsoftheoilintotheglass.

Canyouseethethreeingredientsseparateaccordingtotheirdensities?Honey,theheaviest,settlesatthebottom.Waterrestsinthemiddle.Andoil,beingthelightest,risestothetop.Canyoupicturehowthewater,oilandgassettleinareservoir?

science experiment: oil and water don’t mix

When crude oil accumulates in underground reservoirs, it is often accompanied by natural gas and water. The natural gas is lighter than the oil, so it rises higher in the reservoir and forms a layer on top of the oil. The water is heavier than the oil, so it sits on the bottom. You can see this phenomenon at work by carefully combining ingredients with different densities. This simple experiment will show you how.

CHAPTER 4 DRILLING CHALLENGES

Extracting the OilYou’ve learned a lot so far about how petroleum forms and how it’s

found. Once a well site has been selected, the drilling and exploration

crews haul all of the necessary supplies and equipment to the drilling site

to begin the complicated, and sometimes dangerous, task of retrieving

oil.

The challenges in oil production start with the locations where

petroleum is found, which is often in hard-to-reach locations. In Saudi

Arabia, a great deal of petroleum is found beneath harsh, remote

desert (temperatures at Shaybah field, deep in the Rub‘ al-Khali,

can reach as high as 55 ºC (131 ºF) in the summer months). All the

supplies and equipment necessary for developing these fields must be

below: Miles and miles of sand dunes make for incredible challenges.

Todrillforoilinthedesert,roads,airstripsandbuildingstohousepeopleandmachinerymustbebuilt.Watermustbefound,orpipedinifitcan’tbefoundnearby,and,often,desaltedandcleaned.

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Themassivestructuresbuilttodrillforoilorgasarecalleddrilling“rigs.”Theycomeinmanyshapesandconfigurationsbuttheyallperformthesamebasictaskofdrilling.Whatthey’redrillingformaydiffer.Drillingrigsareusedtodrilltestwellsinsearchofoil;othertimes,theyareusedtodrillforcoresampleswithwhichtoanalyzetheearth’scomposition.Inotherinstances,theyareusedtodrillthewellsthroughwhichtheoilwillactuallyrisetotheearth’ssurface.

Todrillatypicalvertical,onshorewell,apreliminaryholeis“spudded,”ordug.Aderrick—thetalltoweryouseeinmostoilfields—issetuptoholdthedrill,andcasingissetintotheholetokeepthesidesfromcollapsing.Thenthedrillingresumes.Thedrillbitisattheendofwhat’scalledthe“drillstring.”Thisisasequenceofconnectedpipesections,withaheavytube-shapedpiececalledadrill“collar”attheendtoaddextraweighttothedrillstringandholditinplace.

Theterm“rig”includesallofthedrillingmachineryandthescaffoldingthatsupportsit,includingtheplatform,derrick,drill,turbinesandmore.

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Bit by BitMost petroleum reservoirs are hundreds or even thousands of meters

underground. That means the drill bits have to go through layer after

layer of soil, rock, salt and whatever other obstacles are in the way. The

drill bits heat up tremendously from the friction of grinding through

the rock (think about what would happen if you rubbed a piece of metal

against a rock really quickly). To cool the bits down, the drilling crew

pours a mixture of chemicals called “mud” down the drillstring. In

addition to cooling the bit, the mud also sweeps away the bits of rock

and debris that can clog the drill. The design of a drilling rig will also

differ depending on whether it will be used on land (onshore) or in a

body of water (offshore).

Since drill bits have to work even harder in unconventional reservoirs,

and they cost oil companies time and money when they break, special

designs have been created to make them even stronger. Saudi Aramco

has worked with outside companies to test many different designs to

find just the right materials to cut through the varied layers of the earth

surrounding petroleum reservoirs. Many recent drill bit designs feature

small chunks of synthetic diamond covering the head of the bit. Since

diamond is one of the hardest substances in the world, it makes an

excellent cutting edge.

Broken DrillstringsThe depth of the wells in Saudi Arabia creates its own set of problems.

In Chapter 3, you learned that the oil reservoirs in Saudi Arabia are

primarily found in a layer of the earth known as the Arab Zone. The

deeper the hole, the greater the stress on the drillstring, which, over

greater lengths has a tendency to flex or bend. If it bends too much,

it will break, which is not only costly due to the fact that drill bits are

expensive to replace, but also creates other problems.

When a drillstring breaks, drilling on the well must stop while the broken

string is retrieved. This is done by a process called a “fishing operation,”

and the men who perform the fishing operation are called “fishermen.”

The fishing operation varies depending upon where, exactly, the

above: As tough as they are, drill bits do get dull and must be replaced periodically. Unfortunately, one bit will not make the entire journey from the surface to the petroleum. Because the size and shape of the holes being drilled are not always the same, drill bits are also made in a variety of patterns.

Intheearlydaysofoilproduction,actualmudwasusedasthecoolantthatwaspoureddownthedrillstring.

measure density of the rock layers, electromagnetic resistance and more)

are mounted on the drill bits and drillstrings. They can transmit detailed

information to drilling crews on the surface, helping the crews detect and

resolve problems before they become critical. Combined with improved

drill bit design, these advances have greatly reduced the likelihood of

broken bits and drillstrings.

Pressure ControlThe challenges don’t stop once a well has been drilled. Getting the

petroleum out of the reservoir is also complicated. Remember, the

pressure within the earth is high—higher than it is on the surface—and

this pressure typically pushes the petroleum upward. If petroleum filling

the pore spaces within rocks is like water filling a sponge, reservoir

pressure is like squeezing that sponge into a small bottle, and then filling

the bottle with liquid. When the bottle is opened, the liquid will take the

easiest path out—up the neck of the bottle.

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drillstring breaks. Another important factor is whether or not there is

toxic material surrounding the drillstring. Once these questions are

answered, the fishermen use special tools that can either cut into the

broken piece or attract it (like a magnet) and pull it out.

The drilling of horizontal wells is an innovative solution to the problem

of retrieving oil from hard-to-reach places. However, horizontal wells are

much longer than vertical wells (since they have to go down to the right

level and then run horizontally for a considerable distance) and therefore,

they actually cause more stress to the drillstring.

These days, fiber optic cameras and many kinds of sensors (which

above: If a drillstring (like the one seen here) breaks, “fishermen” are called in to perform a fishing operation. First they have to figure out where the string is stuck. In an open hole? Inside the casing? below: Horizontal wells include a section (or multiple sections) that runs horizontally through the reservoir. You’ll learn about horizontal drilling in Chapter 8.

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above: A well shaft is like the neck of a soda bottle. When the drill bit pierces through the cap rock (the dam) covering the reservoir, it’s like taking the top off the bottle. What would happen if that bottle was shaken up first? The pressure inside the bottle would make the soda blow out the top. The same thing can happen when drilling for oil or gas. This is called a blowout. right: Drilling crews cap wells with heavy-duty valves called blowout preventers, seen here, to help prevent blowouts, but an accurate understanding of the reservoir is also critical to predicting overpressure.

above: These tiny microchips can be attached to drill bits and drillstrings to help collect and transmit information from the well to the crew on the surface.

offshore drilling

Oilseepshavebeendiscoveredinoceansaroundtheworldformanyyears,andjustliketheseepsonland,theyaretakenascluesthatpetroleumreservoirsmaybeburieddeepbeneaththeseafloor.Undersea,oroffshore,wellsweredrilledinshallowcoastalareasasearlyasthebeginningofthe20thcentury,butextractingpetroleumfromtheocean’sdepthswasnotafocusuntildemandgreatlyincreasedafterWorldWarII.

AramcogeologistssuspectedthatlargepetroleumreservoirsexistedintheseabedunderneaththeArabianGulf,particularlyinanareacalledSafaniya.Thecompanybegansearchingforthosereservoirsin1949,andbuiltitsfirstoffshoredrillingrigin1950.In1951,itdiscoveredtheSafaniyafield.

Themanylayersandobstructionsundergroundmeandrillershavetoapproacheachreservoirfrommultipledirections(advancementsinhorizontaldrillinghelpwiththistoday).Becauseeachoffshoreoilrighadtobeattachedtotheseabedtokeepfromfloatingaway,AramcosoonrealizeditwouldtakemultipleyearsanddrillingrigstoreachalltheoilinSafaniya.So,theycameupwithasolution:amoveabledrillingplatform!

Afterseveralyearsofresearchanddevelopment,Aramcolauncheditsfirstmobiledrillingplatformin1958.ItwasnamedAramcoMobileDrillingPlatform1,orAMDP-1.Thatbasicmodelisstillinusetoday.

background: Safaniyaistheworld’slargestoffshoreoilfield.Tofindit,Aramcobuiltitsfirstoffshorerig.Tokeeptherigfromfloatingaway,Aramcobuiltaplatformtoholdtherigandworkers,andthenanchoredthatplatformtotheseabed.

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As the oil and gas are removed, the pressure in the reservoir begins to go

down. At some point, it will dip low enough that the oil will stop flowing

up the well shaft. In some cases, oil companies reinject natural gas into

the reservoirs to keep the pressure up. In other cases, the pressure is

supplied by water (most commonly seawater), which is pumped into

special “injection wells” at the outer edges of the reservoir.

Some petroleum reservoirs, however, are actually under too much

pressure—a condition known as overpressure. Overpressure is caused

by the fact that the deeper underground the reservoir is, the higher the

pressure in it will be. Non associated natural gas reservoirs, for example,

tend to be much deeper than oil reservoirs, so overpressure is always a

concern when drilling into them. In an overpressured reservoir, when the

drill bit pierces the cap rock, the high-pressure in the reservoir can force

oil or gas to rush up the well shaft to the surface, like soda exploding out

of a bottle that has been shaken up. This is known as a blowout.

Formation DamageYou read earlier about drilling mud, the stuff that is poured down the

drillstring to cool and lubricate the drill bit and flush out the pieces of

rock. Over time, drilling mud has come to have a lot of other ingredients

in it. It can also be either water- or oil-based, depending on the needs of

a particular well.

One issue with the chemicals in drilling mud, however, is they can invade

the reservoir rock and damage it—a problem known as “formation

damage.” Xanthan and similar chemicals, known as polymers, are used

to form plugs that prevent the chemicals in drilling mud from invading

the reservoir. Polymers also lubricate the drill bit, making it less likely

to snap from the friction of drilling through hard rock. However, the

polymers themselves can create problems for drilling because they can

build up in the well shaft and in the drillstring (imagine wads of chewing

gum building up on the underside of your school chair), creating a “filter

cake” that can cause the drill bit or drillstring to get stuck or snap. The

polymer residue must be removed, but care must be taken because the

strong acids commonly used to dissolve the polymers can also destroy

the drilling equipment, create formation damage in the well shaft and

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Drillingmudisfullofchemicalswithnamessuchasxanthan.Ifthewordxanthansoundsfamiliartoyou,itisbecausexanthanisalsofoundinchewinggum!

above: An explosion of soda is easy to clean up, but gas and oil are not soda. They are very flammable, and when they explode out, catastrophic fires can occur.

TheplatformofAramco’sAMDP-1wasshapedlikeanisoscelestriangle,withtwosidesmeasuringroughly29meters(94feet)andonesidemeasuringroughly32meters(104feet).Theplatformwasabout3.5meters(10feet)thickandenclosedwithsteelsides.Whenmovingthroughthewater,itactedlikeaship’shullandfloated.

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Thelegsonanoffshoreoilrigareequippedwithgearsthatallowthemtomoveup,whentherigisbeingmovedintoposition,anddown,whentherigisreadytobeplantedontheseafloor.ThelegsofAramco’sAMDP-1wereeachabout38meters(125feet)long.

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Becauseoffshoreoilrigsareoftenbuiltinthemiddleoftheocean,helicoptersareusedtotransportworkerstoandfromtherig.

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loay mashabi, petroleum engineer

After visiting the Saudi Aramco Exhibit in Dhahran as a schoolboy, Loay Mashabi’s dream was to work for the company. Raised in Jiddah, he knew little about Saudi Aramco before the trip to Dhahran. The experience, however, left him knowing exactly what career he wanted to pursue.

After going on to complete the College Preparatory Program (CPP) run by Saudi Aramco, Mashabi entered King Fahd University of Petroleum and Minerals (KFUPM), where he completed a degree program in petroleum engineering.

Mashabi then fulfilled his boyhood dream by beginning work as a Saudi Aramco production engineer. Despite being just 26 years old and only having been in his position for three-and-a-half years, he now has responsibility for 120 wells in the Ghawar field. His job is to ensure the wells are free of problems, known as “well integrity,” by conducting numerous tests and surveys, as well as analyzing data provided by other departments. On average, he spends five to 10 days a month away from home, mostly to supervise work being carried out on the wells.

Mashabi is an active member of the renowned Society of Petroleum Engineers (SPE). He continues to advance his learning by taking advantage of the many training courses offered by the company.

In addition to his responsibilities, Mashabi still finds time to scuba dive and play water polo in his free time. In fact, he is training to become a scuba diving instructor. Mashabi believes that with determination, others too can fulfill their dreams, “With a positive attitude you will learn a lot,” he said. “Communication skills are important because 90 percent of what I do is reliant on other people. If you have an open mind and are able to work with people from various backgrounds, you can fulfill your dreams.”

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damage the surrounding environment. Saudi Aramco chemists have

developed a treatment for filter cake using enzymes specifically targeted

at dissolving the polymers, followed by a treatment with diluted acid to

finish the process.

Reservoir ManagementSaudi Aramco has a team dedicated to dealing with all the complexities

that go hand in hand with drilling wells and retrieving the petroleum

from them—the Reservoir Management Department. Reservoir

Management studies and makes computer models of the reservoirs

to determine their exact makeup; chooses the best sites for drilling;

and predicts, prevents or fixes problems such as formation damage,

collapsing well holes, blowouts and more. The task is huge, and

Reservoir Management must work with many people throughout the

company, from geologists to computer systems technicians.

above: Enzymes are a type of protein that helps start or speed up chemical reactions, such as this one. Saudi Aramco’s enzyme technique has been quite effective at removing polymer buildup without causing formation damage in the well shaft. left: Making and studying 3D models of Saudi Aramco’s petroleum reservoirs is not just the responsibility of the Reservoir Management Department.

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Polymerstakedifferentformsasaresultofthemoleculesthatmakethemup.Moleculesaremadefromatoms.Thepropertiesofmoleculesdifferdependinguponwhichatomstheyaremadefromandhowthoseatomsbondtogether.

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above:“Myjobcanbeverydemandingbutisalsoveryfulfilling.Itgivesyouastrongsenseofresponsibilityandownership.”

AproductionengineerisusuallyassignedtheresponsibilityofoneormoreGasOilSeparationPlants(GOSPs)orWaterInjectionPlants(WIPs)oragroupofoil,waterorgaswells.

Inmanycases,thisresponsibilityissharedwithanotherengineer.Productionengineersmonitorwellboreintegrity,ensurethewellisperformingefficientlyandgatherdatatoenableproperreservoirmanagement.Thisisdonebydesigning,planningandwitnessingwelltestingandsurveillanceofoil,waterandgasinthedesignatedarea.