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TitleGeology Geophysics in Oil Exploration[1]
TagsFault (Geology) Sedimentary Rock Clastic Rock Sandstone River Delta
File Size11.1 MB
Total Pages70
Document Text Contents
Page 1

2010 

Mahmoud Sroor 

 
 

Geology & Geophysics in Oil Exploration

Page 2

Geology & Geophysics in Oil Exploration 
 

2  Geology & Geophysics in Oil Exploration                                                                                                                                                      Mahmoud Sroor

 

 

Contents 

Introduction………………………………………………………..3

Chapter 1: Sedimentary Rocks …………………………………....4

Chapter 2: Depositional Environments ……………………………14

Chapter 3: Structural Geology …………………………………….18

Chapter 4: Petroleum Geology …………………………………....27

Chapter 5: Seismic Survey …………………………………….….32

Chapter 6: Seismic Data Processing ………………………………38

Chapter 7: Seismic Data Interpretation ……………………………45

Chapter 8: Well Logging & Mud Logging ………………………..53










By:

Geophysicist: Mahmoud Ahmed Sroor
Mob: 002-0129990480

E‐mail: [email protected] 

             [email protected]

Page 35

Geology & Geophysics in Oil Exploration 
 

35  Geology & Geophysics in Oil Exploration                                                                                                                                                      Mahmoud Sroor

 

Seismic equipments: 

1‐Determining location: 

Land: 

 Conventional survey instruments such as Thelodolite 

Electromagnetic distance devices (EDM) 

Global positioning system (GPS), which is commonly, used method. 

Marine: 

Radio positioning, Transit satellite positioning 

Streamer locations by using Tail Buoy 

Global positioning system 

2‐Seismic sources: 

Land Sources: 

A‐Impulsive  sources: which are divided  to Explosive sources such as Dynamite 
(common  in Petroleum exploration), and Non Explosive such as Weight drop & 
Hammers (common in shallow seismic investigation). 

B‐Non  impulsive  sources:  the main  common  is Vibroseis which  is  a  designed 
vehicle lift its weight on large plate in contact with ground surface in sweeps.  

Up Sweep: Frequency begins low & increase with time. 

Down Sweep: Frequency begins high & decrease with time. 

Marine sources: 

Air gun: the common in offshore survey (first produced in 1960). This gun 
releases highly compressed air into water. It uses a compressed air at 2000‐
5000PSI to produce an explosive blast of air. Several air guns with different sizes 
are fired to enhance their initial pulses & reduce their bubble effects.  

 

3‐Seismic detectors: 

Land detectors (Geophone): 

It is a device is used to detect the sound waves. It consists of coil of wire suspended from spring 
&  surrounded  by  (W)  shaped  magnet.  Upward  energy  from  seismic 
source is recorded as electrical current generated by movement of coil. 

Marine detectors (Hydrophone): 

It is a device used to detect the pressure waves. Upward energy is 
recorded as electrical current generated by piezoelectric device (which 
generates a voltage if acted with pressure). 

 

 

Weight drop 

Vibroseis 

Air gun 

Geophone 

Hydrophone cable

Page 36

Geology & Geophysics in Oil Exploration 
 

36  Geology & Geophysics in Oil Exploration                                                                                                                                                      Mahmoud Sroor

 

Seismic acquisition:  

It is the generation and recording of seismic data. Acquisition 
involves many different receiver configurations, including 
laying geophones or seismometers on the surface of the Earth 
or seafloor, towing hydrophones behind a marine seismic 
vessel to record the seismic signal. A source, such as a vibrator 
unit, dynamite shot, or an air gun, generates acoustic or 
elastic vibrations that travel into the Earth, pass through strata 
with different seismic responses and filtering effects, and 
return to the surface to be recorded as seismic data. 

Seismic Crew: 

A seismic crew is a team of people who conduct seismic tests to gather information about the geology of an area of 
interest. The biggest employer of seismic crews is the oil industry, which conducts extensive seismic research before 
drilling new wells for oil.  

Party Chief: is the manager of the crew 

Camp Boss: is responsible for camp services such as food & beverages. 

Company Representive: is a person from the owner company to follow the 
acquisition survey.  

Mine Clearance: responsible for clear the war explosives before survey. 

Recording: Geophysicist who is responsible for data recording. 

Quality Control: Geophysicist receives the data everyday to check the quality. 

Land Survey: 

Two‐dimensional survey (2‐D): 

Seismic data or a group of seismic lines acquired individually such that there typically 
are significant gaps (commonly 1 km or more) between adjacent lines. A 2D survey 
typically contains numerous lines acquired orthogonally to the strike of geological 
structures (such as faults and folds) with a minimum of lines acquired parallel to 
geological structures to allow line‐to‐line tying of the seismic data and interpretation 
and mapping of structures. 

The seismic data recorded by 2‐D survey is seismic line. 

Three‐dimensional survey (3‐D): 

The acquisition of seismic data as closely spaced receiver and shot lines such that 
there typically are no significant gaps in the subsurface coverage. 

The seismic data recorded by 3‐D survey is seismic cube. 

 

                                              

2‐D Survey

3‐D Survey

Seismic cube

Page 69

Geology & Geophysics in Oil Exploration 
 

69  Geology & Geophysics in Oil Exploration                                                                                                                                                      Mahmoud Sroor

 


Mud Logging & Testing:


Drilling Mud carries the cuttings to the surface.
It carries also traces about any Hydrocarbons & other substances
The cuttings give great information to geologists about what’s going on in the well.
Analyzing the drilling fluid is called Mud Logging.


Rig Monitors:

It shows:
• Rate of Penetration (ROP)
• Weight on Bit (WOB)
• Total Hook Load (the total force pulling down on the Hook)
• Rotary Speed or RPM
• Rotary Torque ( the twisting force on drill string)
• Pit Volume PVT (the level of Mud tank)
• Mud Weight ( in & out the hole)
• Mud temperature & Pump Strokes
• Casing & Stand Pipe Pressure

Mud logger can combine Rig information with other information from Drillers &
Wireline Operator


Chromatograph:

It displays the percentage of Hydrocarbon gases in Mud returns to the surface.
It consists of sensors integrated in Mud Return Line to detect gases.


Core Plugging Apparatus:

It is apparatus takes a small plug out from the Core Sample.
Mud logger can analyze the plug to give idea what a large Core Sample contains.


Fluoroscope:

It is a device contains Ultraviolet lamp.
When mud logger or geologist puts cuttings or Plug in the Fluoroscope, it will glow
or flours when contain hydrocarbons.


Microscope:

It helps the mud logger or geologists to identify formations, & know very small
characteristics & fossils also.


Vacuum Oven:

It is used to dry up formation samples

Analytical Balance:

It is a device used to calculate the rock density & porosity for a fixed weight.

Porosimeter:

It measures the porosity of the rock (more pore space is more space for oil).

Gas Analyzer:

It analyzes hydrocarbon gases in mud & detects Hydrogen Sulphide & Carbon
Dioxide (Non hydrocarbon Gases).
• Sour Gas: Gas that contains Hydrogen Sulphide
• Sweet Gas: Gas that contains little or no Hydrogen Sulphide



Chromatograph

Vacuum Oven

Porosimeter

Page 70

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