BRIEF INTRODUCTION TO UPSTREAM INDUSTRIES AND PRESENT INDIAN SCENARIO
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EXPLORATION CYCLE• The following methods are sequentially used in the exploration for crude oil and
gas
Introducton to Petroleum Exporation2
Gravity / Magnetic Surveys
Geological Field Mapping/ Remote Sensing
Seismic Data API (2D/3D)
Prospect Identification
Drilling
Reservoir Studies
Production
Well Logs & VSP
BHS &
Simulation
GEOLOGY
Even where the organic matter can become mature, not all of it becomes petroleum.
In a typical case a normal marine shale with only 1% original organic matter will
have less than a third of it converted to the hydrocarbon molecules that make up oil
and natural gas (Waples, 1981).
The rest remains behind as an insoluble organic residue
GEOLOGY
• However, the least efficient step is yet to come.
• Of all the petroleum generated, only a small part, usually less than 1%
(Hunt, 1977), is able to undergo migration out of the source bed to
accumulate within a porous and permeable reservoir.
• The majority of petroleum, or even in some cases all of it, will be
dispersed for lack of a good arrangement of strata to trap it, or will leak
out to the surface, for lack of a good impermeable seal or caprock.
GEOLOGY
• If any one of these factors is missing or inadequate, the prospect
will be dry and the exploration effort will be unrewarded.
• Not surprisingly then, less than half of the world's explored
sedimentary basins have proved productive (Huff, 1980) and
typically only a fraction of 1% of the petroleum basin's area, and at
most 5% to 10%, is actually prospective (Weeks, 1975).
GEOLOGY
• A trap is a geometric configuration of structures &/or strata, in which permeable rock types (the reservoir) are surrounded & confined by impermeable rock types (the seal).
• Most traps fall into one of three categories: structural traps, stratigraphic traps, or combination traps
STRUCTURAL TRAP
STRATIGRAPHIC TRAP
Geological inputs
• Remote Sensing
• Geological map
• Cross section
• Sediment thickness
• Type of fill
• Subsidence history
GEOPHYSICAL DATA ACQUISITION
Data Acquisition
Data Interpretation
&
Data Processing
Reservoir Estimation
GEOPHYSICAL DATA ACQUISITION
Layering of sediments above
the earth’s surface can be
seen from Geological outcrops
But how do we “see” the
picture that is hidden below?
ANTICLINE
Anticline Outcrop (Cross Section View)
GEOPHYSICAL DATA ACQUISITION
• Seismic surveys allow geophysicists to see beneath the surface and map areas that are not visible.
On land Seismic Data Acquisition
Offshore Seismic Data Acquisition
Pre-drilling Inputs
Prospecting
Geological
Geophysical
Geochemical
Geological mapping &
traversing
Gravity, Magnetic &
Seismic
Geobotanical Microbial survey
geophysical prospecting
Gravity prospecting includes measuring a field of forcein the earth that is not generated by the observer. TheField instruments are designed to measure differencesin gravity. The Variation in gravity depend on lateralchanges in the density of earths materials. Mostsedimentary rocks have densities lower than basementrocks, make possible to map boundaries and determineapproximate depth distribution of sedimentary basins.
Magentic prospecting gives information to determinethe depth to basement rocks to locate and defineextent of sedimentary basins. The Sedimentary rocksexert small magnetic effects compared to igneousrocks. All variations in magnetic intensity measurableat surface result from topographic or lithologic changesassociated with basement or igneous intrusives
geophysical prospecting
• The seismic methods for exploration utilizes the fact that the reflecting surfaces between two rock beds have different lithology and density. The main purpose is to know depth of subsurface sedimentary beds and their alignment and structure like horizontal beds, inclined beds, folds faulted beds etc. Sound energy is either generated through a dynamite blast within a shot hole or a vibrater or a airgun (in case of marine surveys). The elastic waves (P-waves or primary waves) while propagating through sedimentary beds, part of energy will bounce back whenever they strike boundaries of rock beds having different densities of hardness. These reflections are received by geophones which in turn recorded along with time of their arrival which is called seismogram.
Geochemical Modelling
Surface & subsurface seeps
Organic richness of sediments
Thermal history
Identification of maturation window
Requirements for exploring a Basin
• Geological map
• Cross section
• Sediment thickness
• Type of fill
• Sequence
stratigraphic model
• Subsidence history
Surface & subsurface
seeps
Organic richness of
sediments
Thermal history
Identification of
maturation window
Identification of reservoir facies
Seal integrity
Possible traps
Migration paths
It is the science / art of making hole or bore in anobject.
Since we are concerned withpetroleum, so we can define drilling as a science ofmaking a hole in earth’s crust (called as an oil / gaswell) down to a desired depth in search ofpetroleum (oil or gas).
DRILLING
DRILLING
To study the science of drilling we have to divideit into two categories:
Drilling Engineering.
Drilling Technology
PRODUCTION, PROCESSING & TRANSPORTATION
Well FluidProcessing
Tankage
Value Addition
Well Completion.
Well Testing.
Well Stimulation.
Artificial Lift Systems.
Workover Operations.
Oil/Gas processing.
Pressure maintenance.
Production Activities
Operation & Maintenance of
Production facilities & pipelines.
Production of Value Added
Products.
Transportation of Oil/Gas.
Design/Construction of
Onshore/Offshore Production
Facilities.
Production Activities
Effective Gas utilisation.
Short/Long term production
plans and implementation.
Implementation of EOR
schemes.
Safety in Production
Operations.
Production Activities
ARTIFICAL LIFT
ENHANCED OIL RECOVERY
ENHANCED OIL RECOVERY
SEDIMENTARY BASIN
• “An unit of lithosphere which subsided as a function of time and received sedimentary succession unique to it.”
More than 600 basins- identified globally.
Active hydrocarbon exploration - in about 400 basinsworld wide.
About 180 basins- under commercial production.
The ultimate H/C resources of the world - about 620billion tonnes.
85% of reserves - confined to only in 30 basins.
INDIA
• India is having vast
land area covered
with sedimentary
rocks.
• Geologically they
are subdivided into
26 sedimentary
basins covering
about 3.14 million
sq. km.
Indian Sedimentary Basins
1958: Cambay Basin
1967: Rajasthan Basin
1889: Assam Shelf
1974: Mumbai Offshore
1980: KG Basin
1973: A&AA FB
1985: Cauvery Basin
Out of 26 Basins 7 are petroliferous