Overview
OG_OV1
Oil and Gas ReservoirsPorous rock (sedimentary)
Rocks mainly carbonate or sandstone
Unconventional gas (shale, coal bed, tight gas)
Trap is needed
A source of carbon (micro-organisms in seawater)
On- or Off-shore
Economics
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Off-Shore Rigs and Platforms
How to Produce HCs?
Drill a well (gas or liquid)
Pressure difference
Mining (oil sands)a
OG_OV4
a. Oil is extracted by heat and caustic, Canada
How to Maintain Pressure Difference?
Reservoir pressure
Gas injection
Water injection
Pumps (surface or submersible)
Gas lift
Minimize damage
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Oil Recovery ModesPrimary
Secondary
Tertiary Chemical
CO2
Steam
In-situ combustion
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Types of Injection Water
Seawater (SRB, SO4 scale)
Aquifer water (fines migration, SO4)
River water (fines migration, TSS)
Produced water (TSO, SRB, H2S)
Commingled water (scale formation)
OG_OV7
a. There are problems with all types of waters
Oil Processing Oil gas separation plant (GOSP)
Separate dissolved gases
Separate free and emulsified waters
Water contains salts (scale, corrosion)
Gases contain hydrogen sulfide
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Problems with Produced Waters
Loss of production Lifting, separation, disposal Scale CorrosionBacteriaEmulsionsSanding
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Chemicals NeededCorrosion inhibitors
Scale inhibitors
Demulsifiers
Biocides
Drag reducing agents
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Types of Wells - FunctionOil producerWater injectionWater disposalWater supplyGas producerGas injectionObservation (T, P, OWC, GOC, GWC)
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Types of Wells – Geometry VerticalHorizontalShort radiusExtended reachMulti-lateral
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Types of Wells – Completion
Open holePerforatedScreensGravel packedSmart completions
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LithologyCarbonates SandstonesMixedShales
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Carbonate ReservoirsCalcite (CaCO3)Dolomite CaMg((CO)3)2
Ankerite Ca(MgFe)((CO3)2)Small amounts of clays, pyrite Middle East, Brazil, USA, UK
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Carbonate Rocks (2)
Dissolve in HClDensity of Calcite = 2.7 g/cc Density of Dolomite = 2.85 g/ccNatural fracturesPositively chargedNever use HF, H2SO4, H3PO3
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Sandstone Rocks Quartz (sand)Feldspars and claysCarbonatesSulfatesIron oxides (hematite)Pyrite (iron sulfide)
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Sandstone Rocks (2) Density = 2.65 g/ccNegatively chargedCementing material Sand production Fines migration HF acid for silica/silicatesNever use HF alone
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Drilling Fluids (Mud)
Water-based All oil Oil-based
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Function Well controlCool-down the drilling bitCarry drilling cuttings Form filter cake Left drilling cuttingsSuspend solids if bit stops
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FormulationWater XC-polymer (xanthan gum)Starch, Poly-anionic celluloseWeighting material KClKOH, Ca(OH)2
Drag reducing agents
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Weighting Materials
Bentonitea
Barite, BaSO4a
Calcium carbonate, CaCO3
Hematite, Fe2O3
Manganese tetraoxide, Mn3O4
a. Insoluble in HCl acid
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Casing Mainly low-carbon steel Joints Examples: J-55 and C-95Letter stands for heat treatmentNumber is the minimum yield
strength of steel
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CementPlaced between rock and casing Zone isolation Water shut-off
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Formulation
Water Class G cementAdditivesLight weight cementFlexible cement
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Sand ProductionWeak rockHigh drawdownWater productionChemical treatments
OG_OV27Unconsolidated Sandstone
Rock Integrity
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ProblemsAccumulation in the well boreErosion to surface valvesErosion to pumpsAll kinds of problems