MICROBIAL ENHANCED OIL RECOVERY

MICROBIAL ENHANCED OIL RECOVERYPrepared byAhmed Mohamed Hussien Aly.Yahia Ali Shawky.AgendaIntroductionInjection MethodsMEOR Metabolites and MechanismsScreening CriteriaEconomicsLimitationsCase StudyConclusion

IntroductionDefinition

Microbial enhanced oil recovery (MEOR) represents the use of microorganisms to extract the remaining oil from reservoirs. Sources

Indigenous Less cost + Difficulty to achieve required actionsExogenous More cost + Produce required metabolites

IntroductionType

AerobicAnaerobicFacultative

Nutrients

Nitrogen source NitratesSugar source MolassesProtein source PhosphatesCarbon source Crude OilInjection MethodsThree general strategies exist for the implementation of MEOR

Injection of nutrients to stimulate indigenous microorganisms Injection of exogenous microorganisms(s) and nutrientsInjection of ex situ produced productsInjection MethodsInjection is done by two ways

Huff & PuffMicrobial FloodingInjection MethodsHuff & Puff method

InjectionInjection MethodsHuff & Puff method

Shut-InInjection MethodsHuff & Puff method

Production from theSame wellInjection Methods Microbial Flooding

MEOR Metabolites and Mechanisms

Gases (H2, N2, CH4, CO2)

Reduce oil viscosity and improve flow characteristics Displace immobile Sweep oil in placeMEOR Metabolites and Mechanisms

Acids (low molecular weight acids, primarily low molecular weightfatty acids)

Improve effective permeability by dissolving carbonate precipitates from pores throat. Significant improvement of permeability and porosity CO2 produced from chemical reactions between acids and carbonate reduce oil viscosity and causes oil droplet to sweelMEOR Metabolites and Mechanisms

Solvents (alcohols and ketones that are typical cosurfactants)

Dissolve in oil reduce viscosity Dissolve and remove heavy, long chain hydrocarbons from pore throat(increase effective permeability) Involved in stabilizing and lowering interf. tension that promotesemulsification Reduce interfacial tensionMEOR Metabolites and Mechanisms

Biosurfactants

Reduce interfacial tension between oil and rock/water surface whichcauses emulsification; improving pore scale displacement Alter wettabilityMEOR Metabolites and Mechanisms

Biopolymers

Improve the viscosity of water in waterflooding and direct reservoir fluidsto previously unswept areas of the reservoir Improve the sweep efficiency of waterflood by plugging highpermeability zones or water-invaded zones Control of water mobilityMEOR Metabolites and Mechanisms

Biomass

Physically displace oil by growing between oil and rock/water surface Reversing wettability by microbial growth Can plug high permeability zones Selective partial degradation of whole crude oil Act as selective and nonselective plugging agentsScreening Criteria

EconomicsMicrobes and nutrients are relatively cheap materials.Cost is independent on oil prices.Implementation needs minor modifications to field facilities.Economically attractive for marginal producing wells.The total cost of incremental oil production from MEOR is only 2 3 $/bbl.

SurfactantCO2 InjectionThermalPolymerWaterfloodingMEORTotal recovery, % OOIPIncremental oil cost, $/bblLimitationsMineral content :Increasing salinity absorbs water from the microbe and negatively affects its growth.Reservoir parameters :Permeability, temperature, pressure, salinity, pH, etc affects selection of our types and our growth.Lack of experience :Study of bacteria metabolism, and relation to subsurface environment, need great effort.Sulfate-reducing bacteria :Produce H2S and SO2 Causing bio-corrosion of the equipment, and contamination of ground water.Case studyCase 1 :-Well stimulation, USA, Johnson, 1979Well: Low productionOil production: 20 bbl/dayObjective: Well clean-outBacteria:-* Bacillus* Clostridium* Up to 105 to 106 cells/ml Nutrients:-* Molasses (4 %)* (NH4)3PO4 (0.02 %)Process: Huff and Puff , Shut-in for 4 weeks, Increase production 350 %

Case studyCase 2:-Microbialflooding, USA, Davidson et al, 1988Problem: * High oil viscosity (21 API)* Unfavorable mobility ratio* Inefficient water-floodingBacteria:-* Clostridium* High producer of CO2 and alcohols Nutrients:-* Water 10,000bbl* Free corn syrup 200,000lb* mineral saltsProcess: Injection, Shut-in for 7 days, Viscosity reduction and Mobility Improvment

ConclusionEOR Methods are specific for specific reservoirs.

Usage of microbes is to produce Bio-chemicals.

Effect of reservoir conditions.

MEOR is economical method.

Questions ?