Play, Lead & Prospect Flashcards
What is the prospect?
A defining idea within the play. A more detailed, less abstract. This is a structure which has a fairly high chance hydrocarbons are there.
A mapped closure by depth conversion of seismic data defined at seals base with SOME UNCERTAINTY and a charged reservoir
What is petroleum?
Organic compound - molecules containing carbon
Hydrocarbon - an organic compound consisting of entirely hydrogen and carbon
Petroleum - naturally occurring, flammable, liquid found in rock formations (chemical energy from trapped solar energy)
What are the steps involved in the exploration-appraisal production process?
Frontier exploration - brand new sedimentary basin
Exploration and appraisal
Discovery and appraisal - discovering how much is present
Development and production - develop the asset
FROM PLAY TO PRODUCT - companies buy in at different stages
What is involved with seismic imaging and interpretation?
1) Seismic survey and data equisition
2) Data processing
3) Seismic interpretation - stratal pattern in seismic data
Velocity analysis - initial interpretation
INTERPRETATION on lines based on - lateral extent of reflection, nature of reflective terminations, seismic facies (the characteristic of the reflections), geometry of sets of reflectors
VARIATIONS in amplitude of seismic reflections contain important information on rock and fluvialproperties
DNIs - direct hydrogen indicators - FLAT SPOT
What is shot record?
The survey consists of; ship & and a towing source with a cable of receivers. Ray pathways along which seismic travel from source to reciever
Increasing reciever interval - decreases accuracy. However, more receivers greater cost
Each pixel on the seismic represents a shot point
The colours represent low and high pressure - the display shows a fluctuation of pressure as a component of time and distance from the show
What are the parameters controlling the results of the shot survey?
1) Water depth
2) Depth of the target
3) Velocities and densities of the water and subsurface
4) The distance of the receiver from the source
5) The depths below the sea surface at which the source are towed
How do we identify events on the shot survey?
CONTAMINATION - ghost, multiples and noise
NOISE - random background contamination which has the same value everywhere
GHOSTS - the consequence of reflection from the sea floor. Therefore each event is followed by another event with opposite polarity. Ghosts cancel the reflector at great distances
GAIN FACTOR - there to compensate for decreased event brightness when signal travels a long distance - 3 is designed to boost late signal by an amount. However, there is a balance as gain also boosts noise
CLIP - helps visual layers
DIRECT, SEAFLOOR, TAGET & CONTAMINATIONS
What are attenuations/extinctions?
The gradual lose of intensity of any kind of flux through a medium
OCCURS - spreading out and frictional lose of sound traces
Reflectors become broader at depth
What is a petroleum system?
Comprises a pod of mature source rock a source of migration paths, reservoir rock, cap rock and traps that can be charged by that source rock to produce oil and gas accumulates (Allen & Allen, 2005)
What is uncertainty and risk?
UNCERTAINTY - with limited knowledge it is impossible to exactly describe the existing stage, the future of the outcome - knowledge = describe the outcome
MEASURE UNCERTAINTY - a set of possible states or outcomes where probabilities are to each outcome
RISK - a state of uncertainty where the outcome has an undesired effect
MEASUREMENT OF RISK - possibility and magnitude of the loss
What is the lead stage?
Potential traps that may contain hydrocarbons therefore still has uncertainty and risk.
Leads require de-risking e.g. additional seismic data and depth conversion to better determine the closure of the trap, allow accurate volumetric calculations and begin to map the reservoir distribution
Describe the stages in the exploration funnel?
1) DATA ACQUISITION - planning (ARCGis) - outcrop, gravity, outcrop & subsurface - 20-30 seismic
1) ACREAGE SUBDIVISION - managing subdivision of territories - BID PLOTS - determined by government and defined by ARC
1) REGIONAL GEOLOGY - integration of data sets
1) PLAY MAPPING - play fairways (hydrocarbon plays) e.g. reservoir processes, top seals. Mapped layers can be merged giving a Commons Risk Segment Map (CRS)
2) MAPPING LEADS - mapping trap structures in plays = leads. Therefore, the area now can be used to estimate volume of hydrocarbons. LEADS - PROSPECTS = decrease uncertainty and risk
3) PROSPECT DEFINITION - a prospect is a lead that has been fully evaluated and is considered for worthwhile drilling. Relies highly on seismic information (understanding fluid and structure of rock)
4 & 5) DISCOVERED HYDROCARBONS - becomes a field. ArcGIS to monitor drilled and undrilled prospect
How does ARCGIS come into play regarding play, lead and prospect of a petroleum system?
To contain oil and gas portfolios from both lead to prospects - data should be kept up to date, a consistent evaluation with a clear trial period, available for ongoing evaluation
PRODUCTION - overlay analysis - geographic features, infrastructure etc.
MANAGING FACILITIES - keeping track of everything at all times from pipeline networks to refineries
PIPELINE MANAGEMENT - monitoring the condition and flow to determine localities - understanding the balance of QUANTITY AND QUALITY
Example and description of a petroleum system?
Santos Basin, Brazil
What is the play?
An idea (defining area). It is an idea on how a petroleum system might work. They are mapped by the spatial distribution A play initially defined as a perception of a model in the mind of the geologist of how a number of geological features might combine to produce petroleum accumulates at a specific stratigraphic level in the basin. With further investigation the play play will be redefined to a trap (petroleum system)
