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1、1,Drilling Engineering,Contents OverviewRig componentsDrillstringDrillbitsFormation pressuresWell control,2,CasingCementDrilling fluidsHydraulicsDirectional drillingDirectional SurveyingMeasurement while drillingSubsea,3,Chap.1 Overview,IntroductionDrilling PersonnelRotary drilling equipmentThe dril
2、ling processOffshore drilling Drilling economics,4,Chap.1 Overview,1.1 Exploration and production licencesIn UK,the secretary of State for Energy is empowered(授权),on behalf of the Government,to invite companies to apply for exploration and production licences on the United Kingdom Continental Shelf.
3、Exploration licences may be awarded at any time.(mainly allow to acquire seismic data,not to drill any deeper than 350 meters.),1.Introduction,5,Production licences are awarded at specific discrete intervals known as licencing Rounds.1.2 Exploration,Development and AbandonmentBefore drilling an expl
4、oration well,company have to obtain a production licence.The licence allow the company to drill exploration wells in the area of interest.,Chap.1 Overview,6,The objectives of exploration well,To determine the presence of hydrocarbonsTo provide geological data(core,logs)for evaluation.To flow test th
5、e well to determine its production potential,and obtain fluid sample.,Chap.1 Overview,7,The phases in the life of oil field,Exploration AppraisalDevelopmentMaintenanceAbandonment,Chap.1 Overview,Role of Drilling,Chap.1 Overview,9,2.Drilling personnel,Drilling a well requires many different skills an
6、d involves many companies.Operator：The oil company who manages the drilling and/or production operations.In joint ventures one company acts as operator on behalf of the other partners.The oil company will employ a drilling contractor to drill the well.,Chap.1 Overview,10,Contracting strategies,Day-r
7、ate contract(日费制)The most common type of drilling contract is a day-rate contract.The operator prepares a detailed well design and program of work for the drilling operationDrilling contractor simply provides the drilling rig and personnel to drill the well.The contractor is paid a fixed sum of mone
8、y for every day that he spends drilling the well.All consumable items(e.g.drilling bits,cement),transport and support services are provided by the operator.,Chap.1 Overview,11,Turnkey contract(大包)The drilling contractor designs the well,contracts the transport and support services and purchases all
9、of the consumables,and charges the oil company a fixed sum of money for whole operation.The role of operator is to specify the drilling targets,the evaluation procedures and to establish the quality controls on the final well.,Chap.1 Overview,12,The operator will generally have a representative on t
10、he rig(sometimes called the“company man”)to ensure drilling operations go ahead as planned,make decisions affecting progress of the well,and organise supplies of equipment.He will be in daily contact with his drilling superintendent（主管）who will be based in the head office of the operator.There may a
11、lso be an oil company drilling engineer and/or a geologist on the rig.,Chap.1 Overview,13,The drilling contractor will employ a tool-pusher（钻井主管 also called superintendent）to be in overall charge of the rig.He is responsible for all rig floor activities and liaises（保持联系）with the company man to ensur
12、e progress is satisfactory.The manual activities associated with drilling the well are conducted by the drilling crew.Since drilling continues 24 hours a day,there are usually 2 drilling crews.Each crew works under the direction of the driller(司钻).,Drilling activity,Chap.1 Overview,14,The crew will
13、generally consist of a derrickman(井架工 who also tends the pumps while drilling),3 roughnecks(钻台工 working on rig floor),plus a mechanic（机修工）,an electrician（电工）,a crane operator and roustabouts(杂工 general labourers)Service company personnel are transported to the rig and when required.Sometimes they ar
14、e on the rig for the entire well(e.g.mud engineer)or only for a few days during particular operations(e.g.directional drilling engineer).,Chap.1 Overview,15,Personnel in Drilling a Well,16,3.Drilling proposal and drilling program,The proposal for drilling the well is prepared by the geologists and r
15、eservoir engineers in the operating company and provides the information upon which the well will be designed and the drilling program will be prepared.Drilling proposal:Objective of the well Depth(m/ft,subsea),and location(longitude and Latitude)of target Geological cross section Pore pressure prof
16、ile prediction,17,Drilling rig to be used for the wellProposed location for the drilling rigHoles sizes and depthsCasing sizes and depthsDrilling fluid specificationDirectional drilling informationWell control equipment and proceduresBits and hydraulics program,Drilling program:,18,4.Rotary Drilling
17、Equipment,19,5.Drilling Process,Fig.4 Typical well in North Sea,20,Installing the 30 in ConductorThe first stage is to drive a large diameter pipe to a depth of approximately 100 ft below ground level using a truck mounted pile-driver.This pipe,usually called casing/conductor,is installed to prevent
18、 the unconsalidated surface formations from collapsing whist drilling deeper.Once this conductor is in place the full sized rig is brought onto the site and set up over the conductor,and preparations are made for the next stage of the operation.,Overview of the process of drilling,21,Drilling and ca
19、sing the 26 holeA 26”diameter bit is generally used for the first hole section(the I.D.of conductor is approximately 28”).This section may be approximately 2000.Whist drilling the 26 hole,drilling fluid is circulated down the drllpipe,across the face of the drillbit,and up the annulus between the dr
20、illpipe and the borehole,carrying the drilled cuttings from the face of the bit to surface.,22,At surface the cuttings are removed from the mud(to collect more cuttings).When the drillbit reaches approximately 2000 the drillstring is pulled out of the hole and another string of pipe(surface casing)i
21、s run into the hole.This casing,which generally 20”O.D.,is delivered to the rig in 40ft lengths.The casing is lowered into the hole,joint by joint,until it reaches the bottom of the hole.Cement slurry is then pumped into the annular space between the casing and the borehole.,23,Drilling and Casing t
22、he 17”HoleOnce the cement has set hard,a large spool called a wellhead hausing(套管头)is attached to the top of the 20”casing.This wellhead housing is used to support the weight of subsequent casing strings and the blowout prevention stack.BOP generally fitted to the wellhead before the 17”hole section
23、 is started.,24,When the BOPs have been installed and pressure tested,a 17”hole is drilled down to 6000ft.Once this depth has been reached the troublesome formations in the 17”hole section,a casing string is used to isolate these formations.When the cement has set hard,the BOP stack is removed and a
24、 wellhead spool is mounted on top of the wellhead housing.,25,Drilling and Casing 12”HoleWhen the BOP has been re-installed and pressure tested,a 12”hole is drilled through the oil bearing reservoir.Whilst drilling through this formation oil will be visible on the cuttings being brought to surface b
25、y the drilling fluid.If gas is present in the formation it will also be brought to surface by the drilling fluid and deteced by gas detectors placed above the mud flowline connected to top of the BOP stack.,26,Petrophysical logsThe drill string is pulled out and a logging tools is pulled in to measu
26、re formation characteristics.the electrical resistance;the bulk density;the natural radioactive emissions from the rock.These tools are run on conductive cable called electric wireline,so that the measurements can be transmitted and plotted almost immediately at surface.these plots are called petrop
27、hysical logs and the tools are therefore call wireline logging tools.,27,CoringIn some cases,it may be desireable to retrieve a large cylindrical sample of the rock known as a core.A donut shaped bit is attached a special large diameter pipe known as a core barrel is run in hole on the drillpipe.Thi
28、s coring assembly allows the core to be cut from the rock and retrieved.,28,Completion the wellto run and cement production casing across the oil producing zone.then to run the tubing inside this casing string.The annulus between the production casing and the production tubing is sealed off by a dev
29、ice known as packer(on the bottom of the tubing).The BOPs are then removed and a set of valves is installed on top of the wellhead.The Xmas tress is used to control the flow of oil once it reaches the surface.,29,To initiate production,the production casing is“perforated”by explosive charges run dow
30、n the tubing on wireline and positioned adjacent to the pay zone.Hole are then shot through the casing and cement into the formation.The hydrocarbons flow into the wellbore and up the tubing to the surface.,31,6 OFFSHORE DRILLING,About 25%of the worlds oil and gas is being produced from offshore fie
31、lds.In the north Sea,exploration wells are drilled from a jack-up or a semi-submersible drilling rig.A jack-up(自升式钻井船)has retractable legs which can be lowered down to the seabed.The legs support the drilling rig and keep the rig in position.Such rigs are generally designed for water depth up to 350
32、 ft water depth.A semi-submersible rig(半潜式钻井船)is not bottom supported but is designed to float.Semi-submersibles can operate in water depths of up to 3500ft.,32,In very deep waters(up to 7500 ft),drillships are used to drill a well.Since the position of floating drilling rigs is constantly changing
33、relative to the seabed special equipment must be used to connect the rig to the seabed and to allow drilling to proceed.If the exploration wells are successful the field may be developed by installing large fixed platforms from which deviated wells are drilled.Once the development wells have been dr
34、illed the rig still has a lot of work to do.Some wells may require maintenance(workovers)or sidetracks to intersect another part of the reservoir.,33,A well drilled from an offshore rig is much expensive than a land well drilled to the same depth.The increased cost can be attributed to several facto
35、rs,e.g.specially designed rigs,subsea equipment,loss of time due to bad weather,expensive transport costs(e.g.helicopters,supply boats).A typical North Sea well drilled from a fixed platform may be cost around$10 million.,34,Jack Up Rig,35,Semi-submersible Rig,36,Drillship,37,Fixed Platform,38,7 DRI
36、LLING ECONOMICS,7.1 Drilling cost in field developmentIt is quite common for drilling cost to make up 25-35%of the total development costs for an offshore oilfield.7.2 Drilling cost estimatesBefore a drilling program ia approved it must contain an estimate of the overall costs involved.When drilling
37、 in an completely new area with no previous drilling data available the well cost can only be a rough approximation.In most cases some previous well data is available and a reasonable approximation can be made.,39,Table 1,Table 2,40,Time related cost:drilling contract,transport,accommodationDepth re
38、lated cost:casing,cementFixed cost:wellheadMore sophisticated methods of estimating well cost are available through specially designed computer programmes.Whatever method is used to roduce the total cost some allowance must be made for unforeseen problems.,41,Table 3,42,Ex1.Cost and Time Distributio
39、n,Rank the major cost elements in the development of the Brae Field given in table 1 and consider the ways in which the costs distribution might change with a bigger and smaller field.Consider how the costs associated with a well(table 2)are related to the time distribution(table 3)for well.,43,Plat
40、form equipment,development drilling,platform structure,pipeline,platform installation,miscellaneous,onshore facilities.,44,45,Ex.2 The drilling process,You are required to drill a well into the Rotliegende sandstone shown on the attached geological cross section(Appendix 1).Consider the following as
41、pects of the drilling operation and how you would drill the well:The rock penetration process-the rock cutting mechanism/tool-the transmission of energy to the cutting tool-the removal of debris from the face of the cutting tool and the borehole.The stability/integrity of the borehole-potential caus
42、es of instability-potential consequences of instability-means of preventing/mitigating problems associated with instability,46,c)The safety of the operation-the greatest source of risk during the drilling operation d)Data and its acquisition-data relevant to the drilling process-data relevant to eva
43、luating the potential oil and gas production of the formationse)The surface equipment requirement,47,48,Chap.2 Rig Components,IntroductionPower systemHoisting systemCirculating systemRotary systemWell control systemWell monitoring system,49,1.Introduction,Six sub-systems:the power system;the hoistin
44、g system;the circulating system;the rotary system;the well control system;the well monitoring system.,51,Most drilling rigs are required to have a method to generate electrical power.The electrical power generators are driven by diesel powered internal combustion engines(prime movers).Electricity is
45、 then supplied to electric motors connected to the drawworks(绞车),rotary table(转盘)and mud pumps(泥浆泵).-电驱动钻机,2.Power system,53,3 Hoisting system(提升系统),The hoisting system is a large pulley(滑轮)system which is used to lower and raise equipment(drill string/casing)into and out of the well.The components:
46、Drawworks:drum,drilling line.Crown block:Travelling block:Hook:Elevator:Deadline,fastlineDeadline anchor,55,Static:Ff=Fd=W/NN is the number of lines,W is the hook load.Dynamic:Ff=W/EN;Fd=W/NE is the efficiency of the system.Output power of drawworks(load on fast line times velocity of fast line):HPd
47、=FfVf/33,000,56,Round trip operations(起下钻):Drilling Ahead（钻进）Running Casing（下套管）Short Trips（短起下钻）,57,The total load of the derrick isFD=W+Ff+Fd,58,Ex.1 The hoisting system,A drilling string with a buoyant weight of 200,000 lbs must be pulled from the well.A total of 8 lines are strung between the cr
48、own block and the travelling block.Assuming that a four sheave,roller bearing system is being used.Compute the tension in the fast line.Compute the tension in the deadline.Compute the vertical load on the rig when pulling the string.,59,4 Circulating system,The circulating system is used to circulat
49、e drilling fluid down through the drillstring and up the annulus,carrying the drilled cuttings from the face of the bit to surface.Drilling fluid(mud)is usually a mixture of water,clay,weighting material(Barite)and chemicals.Functions of mud:to clean the hole of cuttings made by the bitto exert a hy
50、drostatic pressure sufficient to prevent formation fluids entering the borehole.,60,The mud is pumped through the standpipe,kelly hose,swivel,kelly and down the drillstring.At the bottom of hole the mud passes through the bit and then up the annulus,carrying cuttings up to surface.On surface the mud
