- •Physical foundations of oil fields development and enhanced oil recovery methods
- •Introduction
- •1.2 Pool-reservoir properties.
- •1.3. Heterogeneity and anisotropy of reservoirs
- •2.1. Rock pressure and effective pressure.
- •2.2. Reservoir energy types.
- •2.3. The main sources of reservoir energy.
- •2.4. Operation modes of oil deposits.
- •2.5. Elastic-water drive
- •2.6. Dissolved gas drive
- •2.7. Gas cap drive.
- •2.8. Gravity drive
- •3.1. Productive formation.
- •3.2. The reservoir recovery and oil recovery factor (orf).
- •3.3. The well patterns - development systems of production facilities on natural recovery modes.
- •3.4. Enhanced recovery systems
- •3.5. Field development systems
- •3.5.1. Simultaneous production facilities development
- •3.5.2. Successive development systems.
- •3.6. Oil fields development parameters
- •3.6.1. Technological development parameters
- •3.6.2. Borehole grid. Wells’ density.
- •3.6.3. Krylov’s parameters. Compensation factor. Water cut factor.
- •3.6.4. Oil fields development rates.
- •3.6.5. Development stages of the production facilities (oil fields)
- •3.7. Types of water flooding
- •3.7.1. Edge water flooding.
- •3.7.2. Boundary water flooding
- •3.8. Circle water flooding.
- •3.8.1. Direct line drive systems. Their varieties – block systems.
- •3.8.2. Grid water flooding systems.
- •3.8.3. Selective and Spot water flooding.
- •3.8.4. Barrier water flooding system.
- •4.1. Porous formation models.
- •4.1.1. Deterministic model
- •4.1.2. Stochastic-statistical model.
- •4.2.4. Pollard model.
- •4.2.5. Models use peculiarities of the reservoirs of complex structure.
- •4.3. Water saturation and watering.
- •4.4. Reciprocating and non-reciprocating oil displacement.
- •4.4.1. Reciprocating displacement.
- •4.5. Displacement characteristics.
- •5.2. Project documentation.
- •5.3. Field-geologic characteristic of the deposit.
- •5.4. Rational development system.
- •6.1. Geological peculiarities reservoir structure with high-viscosity oil.
- •6.2. The deposit Russkoye
- •6.3. Katangli deposit.
- •6.4. Canada high-viscosity oil deposits.
- •6.5. The main peculiarities of high-viscosity oil deposits development.
- •7.1. Enhanced oil recovery methods classification.
- •7.2. Production stimulation methods (psm)
- •7.3. Enhanced oil recovery methods (eorm)
- •7.4. The forms of residual oil condition.
- •7.5 The reasons of residual oil condition.
- •7.6. The conditions of effective enhanced oil recovery methods use.
- •7.7. Oil deposits management and enhanced oil recovery methods.
- •8.1. Oil displacement by water solutions of surface-active reagents (sar)
- •8.2. Sar adsorption
- •8.3. Sar (surface-active reagent) composition.
- •8.4. Polymer oil displacement.
- •8.5. Micellar-polymer flooding method.
- •8.6. Conformance change or control (straightening the injectivity profile) (cc)
- •8.7. The choice of the areas and wells for injectability profile enhancement technologies implementation.
- •9.1. Filtration flows’ direction changing.
- •9.2. Forced fluid withdrawal (ffw)
- •9.3. Cyclic water flooding.
- •9.4. Combined non-stationary water flooding.
- •10.1. Oil displacement by carbon dioxide (co2).
- •10.2. Oil displacement by hydrocarbon gas
- •10.3. Water-alternated-gas cyclic injection.
- •11.1. Physical processes, happening during oil displacement by heat-transfer agents.
- •11.2. Oil displacement by hot water and steam.
- •11.3. The method of heat margins.
- •11.4. Combined technologies of enhanced oil recovery of high-viscosity oil deposits.
- •11.5. Thermal-polymer reservoir treatment (tpt)
- •11.6. Cyclic steam treatment of producing wells
- •Disp-lace-ment front
- •Ther-mal front
- •Combustion front
- •Disp-lace-ment front
- •Ther-mal front
- •Injection temperature
- •11.8. Thermal-gas method of treatment.
- •12.1. Formation hydraulic fracturing (fhf)
- •12.2. Well operation with horizontal end.
- •12.3. Acoustic methods.
- •Conclusion.
- •The list of symbols and abbreviations.
- •Content
- •Introduction 3
- •4.1. Porous formation models………………………………………………..38
- •4.1.1. Deterministic model……………………………………………………38
10.2. Oil displacement by hydrocarbon gas
At present great attention is paid to the associated petroleum gas utilization. One of the methods of the associated gas use is its implementation as a reagent injected into the injection wells with the purpose of increasing of oil displacement efficiency.
For enhanced oil recovery there are used: dry hydrocarbon gas, high pressure gas, enriched gas and gas-water (water-gas) mixture. When the liquefied petroleum gases and other liquid hydrocarbon solvents are used as the displacing agent, there is another problem of the remaining solvent extraction from the reservoir; the price of the solvent may considerably exceed the cost of oil.
Oil displacement by reagent may be non-miscible or miscible (without the existence of phase boundary). Miscibility of gas with oil in situ is achieved only in the case of light oils (density degassed oil is less than 800kg/m3). The injection pressure of dry hydrocarbon gas is 25 MPa and more, the pressure of the enriched gas is 15-20 MPa.
When mixing (dissolution) gas and oil, the oil viscosity is reduced, the mobility of oil and production rates are increased (see Appendix 1, the Dupuy formula), and ultimately, oil recovery.
The main criteria of the efficiency of the injection process of hydrocarbon gas are the following [3]:
1) The formations’ angles: at the dip angles of more than 150 there is pumped gas in the upper boundary of the reservoir; at smaller angles there is realized dispersed gas injection (in gently sloping structures the gravitational separation of gas and oil is complicated).
2) The depth of the formation: at small depths and high injection pressures the gas breakthrough is possible in the overlying layers; at big formation depth it is required high injection pressure, which is not always technically feasible and economically profitable;
3) The homogeneity of the reservoir by permeability and low-viscosity of oil, at different interlayers’ permeabilities of interlayers can provoke gas breakthrough to the producing wells;
4) Hydrodynamic isolation of the deposits, which prevents leakage of the injected gas.
The well intake capacity is set by experimental way or by the formula of the gas well production rate, multiplying the calculated value on the experimental coefficient. To maintain the pressure on the existing level the total consumption of the injected gas must be equal to the sum of the oil, gas and water production rates reduced to the reservoir conditions. Bottom-hole pressure is calculated with account of the pressure loss on friction and pressure of the gas column. Usually the injection pressure is 15-20% higher than the formation pressure.
For stratified reservoir consisting of the layers of different permeability there is possible premature gas breakthroughs through high-permeability interlayers, which sharply reduces the effectiveness of displacement. Gas breakthroughs are determined by gas factor control and changes in the chemical composition of the gas. To prevent gas breakthrough it is necessary to reduce fluid withdrawal from the wells up to their termination, reduce the volume of the injected gas, inject gas together with liquid.