Understanding the Basics of Gas Exploration and Production

Understanding the Basics of Gas Exploration and ProductionEric K. Albert, PhDAnd some of the career opportunities created by the industry

Our economy runs on energy!In 2009:Energy Information Administration

Natural GasA non-renewable energy resourceUsed in a variety of ways:

Energy Information Administration, 2005

As an energy source:Natural gas burns more cleanly than other fossil fuels

BUT

Still results in CO2 emissions!And unburned natural gas (methane) is considered a greenhouse gas2008 US Natural GasTotal Production21,200 Billion Cubic Feet (BCF)Consumption23,200 BCFImports3,984 BCFExports1,006 BCFWellhead price$7.96 / thousand cubic feetAvg. City Gate price$9.18 / thousand cubic feetTop US Gas Producing State7,760 BCF: TexasEnergy Information AdministrationHow much energy?A BTU is the heat required to raise the temperature of one pound of water 1 degree FahrenheitOne cubic foot of natural gas (volume) contains about 1031 BTUOne candy bar has about 1000 BTU!One cubic foot of gasoline contains about 961,000 BTU! [about 7.6 gallons]Equivalent Energy CostJanuary 2011* Natural Gas price is $4.48 / Million BTU (MMBTU)compared to todays price of $3.19/gallon of gasolinethe equivalent energy price of 1 gallon of gasoline is$25.23 MMBTUPut another way, at current prices, the same energy from Natural Gas is about 1/6 the cost!*NYMEXHow is Natural Gas formed?Trapped organic matter decomposing under pressure and heatIn time, depending on conditions, we get:Coal bedsOil fieldsNatural gasThink: even landfills are recovering methane from decomposing trash

How is it found?Geologists use a variety of means to locate possible sourcesKnowing where it has been found alreadyHistorical geological settingSpecific site location typically uses Seismic methods

Historical Oil and Gas Production

USGSOil: greenGas: redOil & Gas: yellow

Main Phases of Gas DevelopmentExplorationLand identification for sitesLocation of depositsEnvironmental concernsProving potential reservesDrillingLand leasing, right of waysPermitsPad developmentRoads and water infrastructureProductionPipeline constructionMonitoring and compliancePumping and storageWell maintenancePost-productionCapping / sealing wellsWater quality monitoringOther compliance issuesSite reclamationEXPLORATIONSeismic SurveyAn array of geophonesData collection equipmentA noise source Vibrating trucksExplosivesThe reflected sound waves are collected and analyzed with computers to form structural imagesSeismic Surveys

Resolution ResourcesMarcellus ShaleGas deposit known since the 1930sTechnology for recovery not availablePrice of gas too low for cost of drilling6,000 -7,000 underground, maybe morePA gas wells: 35,000+ already in placeEstimates 4,000 per year may be added

Traps

Both of these types of rocks are impermeable, meaning that they do not allow liquids or gassesto move through them!Pore spaces filledPore spaces dont communicate

Geology.comDrilling

DTE EnergyHorizontal drilling is employed to connect to the largest reservoir spaceThe drill string does not turnbut is steered to a horizontal lineThis is accomplished through a steerable drill (Mud Motor)

and a follow-behind probe (Measure While Drilling)

What does a borehole look like?

Top ViewSide ViewNote: the casing system seals off higher elevations of rocks in the well so that only the production area is eventually connected.Well LoggingAfter the well is drilled, a log is madeGamma ray = natural radiation in the rocksNeutron = higher reading means more hydrogen*This along with other data collected in the log helps to indentify if this will be a productive hole

Gamma Ray Neutron*Natural gas is a hydrocarbon!Final StepsAfter the production area is reached:The casing is sealed to this areaThe production area casing is perforated by blastingThe rocks surrounding the production area are fractured (hydraulic fracturing)

PRODUCTIONDeal or No Deal?Even so, after all this, the well might not be productive!Non-productive wells are plugged with cement and operations cease.Hydraulic Fracturing might be repeated in one well several times to attempt to increase pressure and recoveryHigher pressure = higher flow rate = more valuable wellTransportA producing well is then connected to a pipeline for transportAlso, to buffer the effects of seasonal demand, underground gas storage reservoirs are used.In PA there are at least 88 active reservoirs

Well MaintenanceWell production is monitored both remotely and by on-site inspectionsRoutine maintenance of the site is necessary to confirm safety and integrity of the wellWater quality monitoring of nearby drinking water sources, as well as natural sites may be needed (looking for leakage of gas into sources)POSTPRODUCTIONWell LifeA well might produce for 5, 10, even 20 yearsProduction rates decline with timeEventually the rate may be deemed too low to be useful, or non-economicWells are disconnected, sealed (capped) with cement, and a surface vent pipe is installed.Where are the jobs?ExplorationLand identification for sitesSurveyors, Civil engineers, etc.Location of depositsGeologistsEnvironmental concernsEnvironmental techs, biologists, forest technology, chemistsProving potential reservesGeologists, Petroleum & NG EngineersDrillingLand leasing, right of waysPermitsPad developmentRoads and water infrastructureDrillingLand leasing, right of waysParalegals, title search, lawyers, land agentsPermitsHydrologists, civil engineers, land plannersPad developmentCommercial drivers, riggers, drill operators, diesel power generation, construction, welding, electrical, heavy equipmentRoads and water infrastructureSimilar to Pad development

ProductionPipeline constructionHeavy equipment operators, diesel techs, welders, riggers, surveyorsMonitoring and complianceElectronics, computer networking, communications / satellite techs, biologists, hydrologists, chemistsPumping and storageWell maintenance

Post-productionCapping / sealing wellsConstruction, welders, general maintenanceWater quality monitoringOther compliance issuesSite reclamationHeavy equipment operators, forest / reclamation technology

Sam Kier, 1840s

Drake Well Museum How it all got startedQuestions?