Lecture 1,2 Oil and gas wells and their functions in petroleum exploration and

exploration and production

drilled in China in 2000 B.C. with the help of

cable drilling for extraction of salt water.
In the USA the first oil well (depth 25 meters) was drilled in Pennsylvania by Edwin Drake with the use of power plant in 1859.
The birth of the Russian petroleum industry was in 1864, when A.N. Novosiltsev began to drill the first oil well (depth 55 meters) on Kuban, in the valley Kudako - river.

particles fragments of breaked rocks (cutting) with the help of

circulating stream of water in 1848 and used this method for the 1st time for drilling of artesian well in a Saint Dominica monastery.
In 1901 in the USA for the first time new way of drilling was used - rotational-rotary drilling with flushing-out of a well by a circulating stream of a liquid (mud).
In Russia the first well was drilled by the rotary drilling in 1902 (depth of 345 meters) in Groznensk area.
In 1906 Russian engineer A.A.Bogushevsky developed and patented a way of cementing casing string with the help of slurry’s replacement through a casing pipes and casing shoe into borehole annulus.

more than 10 million tons per year. It made up

about 50 % of the world oil production.
In 1923 the graduate of the Tomsk Technological Institute M.A.Kapeljushnikov together with S.M.Volohom and N.A.Korneyev have invented hydraulic downhole motor - the turbodrill.
In 1924 in Azerbaijan the first-ever hole was drilled with the help of the one-stage turbodrill which received the name of Kapelyushnikov turbodrill.
In 1937-1940 A.P.Ostrovsky, N.G.Grigoryan, N.V.Aleksandrov and others developed the new downhole motor - an electrodrill.

blowout in 1953 near village Berezovo in the north of

the Tyumen area.
The first oil exploration drill hole in the Western Siberia gushed on the Mulimlinskaia area in basin of the Konda river in 1960.
During the 30 years (1950-1980) domestic oil production increased more than in 16 times and produced more than 600 million tones.

the well (it begins at the surface)
Cased wellbore (cylindrical surface

of the well)
Non-cased wellbore
Well bottom (well floor)
Casing strings lowered into the well to strengthen its walls
Axis of the well

Well is a vertical or directional round in cross-section mine working with a diameter many times less than its length and which is constructed without any human access.

locations of casing strings, their diameters and total lengths to

be lowered (RIH), diameters of the bits used for each interval of drilling, and also by the location of cemented intervals.

of hole (lift, raise)
ROP - rate of penetration
WOB - weight

on the bit (load)
RPM - revolutions per minute

gas and water shows
Shale instability, hole sloughing
Sticking

avoid flushing the mouth of well by mud and to

provide the vertical direction of the well while drilling in the top part of geological cross-section. As a rule, protective casing is RIH to the depth of 3-10 meters. Sometimes in West Siberia, longer protective casings are used. Their length equals to approximately 30-80 meters.

caving;
to minimize lost circulation into shallow permeable zones;
to cover weak

zone where fracturing may occur;
to provide means for attaching the blowout preventers (BOP);
to support the weight of casing strings located below.

of various complications while drilling.
The number of these strings

depends on complexity of geological cross-section and hydro geological conditions.

the well. With the help of this string oil and

gas come to the surface of the earth from pay zone. Other purposes:
to isolate the producing zone from the other formations (to prevent cross-flow between layers)
to provide a work of the given diameter pump to extract oil from the pay zone;
to protect the production tubing equipment.

casing strings
L1, L2, L3 – depth of casing shoe
d1, d2,

d3 – diameters of the bits
H1, H2, H3 – coordinate of the top end of cement stone column of the casing strings

Well design drawing

cost of a well we often use special intermediate casing

called liner. This string does not reach the mouth of the well. It is hung up into preceding casing string with the help of special equipment. The interval of the well, where casing string is absent, is shown as dotted line.
Look at the following picture.

design of a well in such way that allows drilling

of the well to the project depth without any complications; the well must be reliable within all period of its operation.
Engineers consider planning of a well as a very important task.

be satisfied:

well safety
minimum cost of well construction
usable for particular conditions

Safety

should be the highest priority in well planning. Personal consideration of this item must be placed above all other aspects of the plan. The well plan must be designed to minimize the risk of blowout and other factors that could create problems.

Requirements of well planning

process is to minimize

the cost of the well. Usually costs can be reduced to a certain level as additional efforts are given to the planning.

Requirements of well planning

we use various characters.
By its wellpath we distinguish the following

wells:
straight holes
directional and horizontal wells

TVD – total vertical depth (H);
MD – measured depth (L).

Vertical interval;
Drift angle or buildup interval;
Directional interval.

of oil and gas wells – from several hundred to

several thousand meters.
In terms of the depth of well there are existing 4 types of the wells:
Short wells (up to 1500 m);
Wells of intermediate depth (up to 4500 m);
Deep wells (up to 6000 m);
Super deep wells (more then 6000 m).

on sea (offshore) by using special drilling rigs.
We often

drill not only oil and gas wells but special wells too. For example special wells are drilled in coal and ore industry. Very often the wells are drilled to get mineral water and water for drinking.

Chayvo by company Rosneft (in "Sakhalin -1" Project) with the

help of Fixed Offshore Platform "Orlan". Measured depth (MD) of this well reached 13 500 meters and horizontal displacement reached 12033 meters. Today it's the world record.

Maximum measured depth well

company, Rosneft and American oil and gas corporation ExxonMobil have

discovered oil during drilling on the Universitetskaya-1 well in the Kara Sea.
Drilling was carried out in record time - one and a half months.

Preliminary assessment of the resource base only for this first opening has trapped 338 million cubic meters of gas and 100 million tons of oil , and this is only one of the structures in this field.
The total expenses of this well construction is evaluated approximately 600 MUSD.
The water depth is 81 meters at this site, TVD of exploratory well is 2113 meters.

– wild cats)
Parameter well
Structure boreholes
Prospecting well
Exploratory wells
Production well (recovery well)
Special

wells

These wells are drilled on a significant distance one

from another to get general picture of geological structure of large regions where there are little geological information is available.

Parameter wells - They are intended for a more detailed study of geological cross-section, especially at great depth and for identification of the most promising areas of geological prospecting work.

Structure wells - They serve the purpose of investigating more properly the structures encountered in drilling by key and parameter boreholes and to make up a plan of exploratory-prospecting drilling into these structures.

Prospecting wells - Their general purpose is to discover new oil and gas deposits.

to delineate the pool and to collect the initial basic

data for planning its development.

Production wells - They are drilled into completely prospective oil and gas fields. The category of producing wells includes not only the wells through which oil and gas are recovered in a particular reservoir according to the plan.

formation pressure. For this aim water injection is made into

the formation through these wells. Injection can be made into an aquifer, in this case injection wells are located out of boundaries of particular oil field.
Observation wells. They are drilled to control formation pressure, the position of the water-oil, gas-water and gas-oil contacts during the reservoir development.

into unproductive absorbing layers,
for exploration and production of water,

geological structures preparation for underground gas storages and gas injection into them,
for elimination of oil and gas blowouts.

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