Geophysics
Department of Petroleum
University of Thi Qar/ College of Engineering
Ahmed Jalal Fakher Al- Bahar
2021-2022
Book 1 Book 2
Geology & Geophysics
Geology: it is an observational science. It involves the
study of the earth by direct measurements of rock
properties, either from surface exposures (outcrops) or
from boreholes, tunnels, and mines.
Geophysics: applies the principles of physics to the study
of the earth, for deducing physical features of the earth’ s
surface and its internal structure. Geophysics involves the
study of those parts of the earth hidden from direct view,
by measuring their physical properties, with appropriate
instruments on or above the surface of the earth, remotely
from the measurement targets.
Methods Physical property Suitable for
Geological structure, spatial variation in
Gravitational attraction,
Gravity Density contrast
rock types: for example, salt domes,
shale diapers, reefs and cavities
Magnetic ores, Geometry of basement
Magnetic field variation, below the sediments, sedimentary cover
Magnetic & Electromagnetic Magnetic susceptibility thickness,
contrast geological structures and
archeological studies
Changes in electric
Shallow near- surface lithology changes,
Electric & Electromagnetic conductivity and or Ground water, cavities
permittivity
Refraction (Shallow) Travel time to acoustic Engineering problems
boundaries, amplitude
Seismic (elastic moduli and Geological structure, depositional
density contrast), history, faults, rock layers, reservoir size,
Reflection (Deep)
absorption, velocity shape porosity, pressure, saturation
distribution
Radiometric Radiation intensity Radioactive ores
Geological structures, Shallow salt
Geothermal Temperature domes, Anticlines and Fissures
Ground Penetration Electromagnetic waves Channels, Cables, Caves, Pipes,
Radar - GPR intensity River floor
Date from geophysical tools provide coverage with a spatially
continuous high sampling density of 10-25 m and a vertical
resolution of the order of 10-20 m. well data such as cores and
well logs provide a vertically high resolution of the order of
0.5 m or better at the well location; however, the distribution
of wells is sparse and discontinuous. The detailed spatial
coverage from geophysical data is calibrated with analysis of
well logs, pressure tests, cores, geologic depositional
knowledge, and other information from appraisal wells.
Core
R-521 R-549 R-519 R-508
Vsh EEI30 EEI40 EEI50 Vsh EEI30 EEI40 EEI50 Vsh EEI30 EEI40 EEI50 Vsh EEI30 EEI40 EEI50
South Rumaila Rock Property Wells
Package 1
Top AB – Base F
Package 2
Top L2 – Base N
Package 3
MSM10
Well logging
Seismic reflection & well log
Lithology Volume: inline 1703 through Ru-404 well location
AB - F
LMN
MSM10
Geophysical tools and techniques
Geophysical methods use high-precision sensors (e.g., geophone, hydrophone,
magnetometer, gravity-meter) that measure the physical properties onshore and
offshore, in wells and from air. Rather than the overall magnitudes of these properties,
the small differences in physical properties that exist among various rock bodies are
what we need for interpretation. These differences in physical properties must be
measured accurately. Accuracy of measurements and their analysis rely heavily on the
technological development.
Geophysical tools are deployed from ground surface, at sea, in boreholes, and in
air. There are also measurements from satellites:
Surface: seismic reflection 2D, 3D, 4D magnetics, gravity, electromagnetics.
Borehole: vertical seismic profiling (VSP), cross well seismic, cross well
electromagnetics, microseismic, borehole gravimeter (BHGM), nuclear
Geophysics in drilling
The process of drilling an oil or gas well
requires knowledge of all geologic Static model
features expected to be encountered along
the way- from the surface of the ground to Seismic & model
structures don’t
the target reservoir. Thus, in addition to match
steering the well so as to intersect
hydrocarbon- bearing reservoirs, the
reservoir engineer must ensure that the Mishrif seismic surface
well drills successfully and safely to the
target formations. Update static model with structure interpreted
on 3D seismic
By providing a picture of the subsurface from the surface to the target, geophysical
measurements help ensure a successful drilling program. This geophysical picture helps to:
1. Identify drilling hazards that may lead to an uncontrollable well;
2. Describe construction hazards; predict what lies ahead of and around the drill bit; and
3. Illuminate what exists above and below the well bore in a horizontal or highly
deviated well.
Seismic section with Interpreted Horizons
W E
Dammam
Top Rus
Top Tayarat
Sadi
Top Mish
Top Ahmadi
Top Uppershale
N
Top YRB
peak
trough
W E
S
Video
يتك و باطوواألرا من األوورا ملرئوويا التالووايا اتاااووياالتغووات الرووجا ات وول ا اغئا وويا وياسوول ا
اغ ووا ا ازازااوويا ضووعالوورا ادنسووا ا او ماغااتاوويا اتووياا ل وومالرووجا اغو تاا ووا ا ل هووااأل و ا
ابلك را.
.3ا ارباا)(Core .1ا اقشلةااا).2 (Crustا اوبيا )(Mantle
Continent Ocean
Crust Granitic layer
Sedimentary rocks
and sediments
)(SIAL
Mantle Volcanic rocks
Conrad discontinuity
Core Basaltic layer
)(SIMA
Moho discontinuity
Mantle
ألعوودساسوووغشا اقشووولةايتووول ا وو را()35-40اكووو ايا وووساكهوووحاسوووغاهااي ووما اوبووواسا ووويا اقوووان ا اوووج
()90اك ايا غاايبرغاسغاهااي ماقاعوابا اب وانا اغ اتوا ا و ايا()6اكو ا.ايكو با اقشولةا ويايغوا ا
أل االرجاستحا اوبيا ياأل تقيايدلجا تقت األ ه ا) (Moho discontinuityغاراالتبواناهو ا الوتحا
ا يايقت األ ه اياطغع جاآ ولامرغوا انيئو ا أللآةاارت ب للفاياي ايااباانيئا استحا من اكقا رهاانخئا
ايقتو أل هو ا سووتحا من ادتاسووغشا اقشوولةا من ووايا.ااذبا و با اقشوولةايغلووحاذاووشا اوووز ا او ياكقو ا و
اوووو ياكئهووووحا اقشوووولةالوووورا اوبوووويا قوووو اهوووو ا اتقتوووو الرووووجالغوووو ا()33اكوووو اي ووووما اقشوووولةا اقان وووويا
ا()10اك اي ما اقشلةا اغ اتايا.ايتك با اقشلةاألراألبقت رانتال ت راهغاا:
• SIAL Granitic )Acidic (on the top
• SIMA Basaltic )basic (on the bottom
ئهحاهاي را اتبقت رايقت امو نلتا) (Conrad discontinuityطلوببا ات ولا اغئوا يا وياألا نوا ا
ود اتبقوويا اغعوواتبااكووعا اتبقت و رايا يخترووااألباعوويا اقشوولةا وويا اقووان ال هوواا وويا اغ اتووا ايااذايت
اباداتايا) (SIMAطه نةالاألوياي وما اقوان ا اغ اتوا ا غوااكقتهولا و تا اتبقويا اكلنايتاويا)(SIAL
ي ما اقان ا قطا.
كئهحايقت األ ه ا اقشلةا ا لاألتوانليا) (Heterogeneous crustلرا اوبيا مكلللود ا
ووو ر يوووان،ايا اعووواا ا ) (Birchالتبووولااباه ووواةاأل تقووياانتقاااووويا ووغرا اوبووويايتوول الغقهوووااألوووا
()300-900اك ايا ساي داه اةاي لايدن وياطااتلم با اكاغااتيا اتو نا( الواتحايا ا واد يا اهورب)
ز اتاوويا او ماغااتاووياألوورا اطووهاألوورا اغشوواكحا او ا امر هغوواا.اه و اا اغ تقوويايعووداألئتووا ااعوودتاناط و
ووغ هاا اهووز ا من وواياذ ا ابووقنا اعغاقوويا اتوويايق و ا ووغراه و اا اغ تقوويا ضووعالوور التبانهووا ألهوودنا
ارغاكغا.
يتك و با ارووباألوورا ووزت را ووان يا ت رووياي هوولبا هغووااأل تقووياانتقاااوويايايت و ااا اوووز ا
اخان ياألراأل تاساتريا غااكا با اوز ا اد رياصرباألقاااألرا ا ديدا ا ااحا.
