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1、1,Drilling Engineering,Contents Overview Rig components Drillstring Drillbits Formation pressures Well control,2,Casing Cement Drilling fluids Hydraulics Directional drilling Directional Surveying Measurement while drilling Subsea,3,Chap.1 Overview,Introduction Drilling Personnel Rotary drilling equ
2、ipment The drilling process Offshore drilling Drilling economics,4,Chap.1 Overview,1.1 Exploration and production licences In 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 Kingdo
3、m Continental Shelf. 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 Abandonme
4、nt Before drilling an exploration 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 hydrocarbons To provide geological data(core, logs)
5、 for evaluation. To flow test the well to determine its production potential, and obtain fluid sample.,Chap.1 Overview,7,The phases in the life of oil field,Exploration Appraisal Development Maintenance Abandonment,Chap.1 Overview,Role of Drilling,Chap.1 Overview,9,2. Drilling personnel,Drilling a w
6、ell requires many different skills and 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.
7、1 Overview,10,Contracting strategies,Day-rate 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 operation Drilling contractor simply provides the drilling rig and personnel to drill the we
8、ll. The contractor is paid a fixed sum of money 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 t
9、he transport and support services and purchases all 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
10、,The operator will generally have a representative on the 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） w
11、ho will be based in the head office of the operator. There may also 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 r
12、ig floor activities and liaises（保持联系） with the company man to ensure 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
13、of the driller(司钻).,Drilling activity,Chap.1 Overview,14,The crew will 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 c
14、ompany personnel are transported to the rig and when required. Sometimes they are 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 d
15、rilling program,The proposal for drilling the well is prepared by the geologists and reservoir 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)
16、 , and location (longitude and Latitude) of target Geological cross section Pore pressure profile prediction,17,Drilling rig to be used for the well Proposed location for the drilling rig Holes sizes and depths Casing sizes and depths Drilling fluid specification Directional drilling information Wel
17、l control equipment and procedures Bits and hydraulics program,Drilling program:,18,4. Rotary Drilling Equipment,19,5. Drilling Process,Fig. 4 Typical well in North Sea,20,Installing the 30 in Conductor The first stage is to drive a large diameter pipe to a depth of approximately 100 ft below ground
18、 level using a truck mounted pile-driver. This pipe, usually called casing/conductor, is installed to prevent 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 pr
19、eparations are made for the next stage of the operation.,Overview of the process of drilling,21,Drilling and casing the 26 hole A 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 h
20、ole, drilling fluid is circulated down the drllpipe, across the face of the drillbit, and up the annulus between the drillpipe 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 th
21、e drillbit reaches approximately 2000 the drillstring is pulled out of the hole and another string of pipe (surface casing) is 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
22、bottom of the hole. Cement slurry is then pumped into the annular space between the casing and the borehole.,23,Drilling and Casing the 17 ” Hole Once 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 sup
23、port the weight of subsequent casing strings and the blowout prevention stack. BOP generally fitted to the wellhead before the 17 ” hole section 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 troubleso
24、me 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 wellhead spool is mounted on top of the wellhead housing.,25,Drilling and Casing 12 ” Hole When the BOP has been re-installed and pressure tested,
25、 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 by 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 detecto
26、rs placed above the mud flowline connected to top of the BOP stack.,26,Petrophysical logs The drill string is pulled out and a logging tools is pulled in to measure formation characteristics. the electrical resistance;the bulk density;the natural radioactive emissions from the rock. These tools are
27、run on conductive cable called electric wireline, so that the measurements can be transmitted and plotted almost immediately at surface. these plots are called petrophysical logs and the tools are therefore call wireline logging tools.,27,Coring In some cases, it may be desireable to retrieve a larg
28、e 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. This coring assembly allows the core to be cut from the rock and retrieved.,28,Completion the well to run and cement production casin
29、g 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 device 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 wel
30、lhead.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 down the tubing on wireline and positioned adjacent to the pay zone. Hole are then shot through the casing and cement into th
31、e 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 fields. 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
32、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 ft water depth. A semi-submersible rig (半潜式钻井船)is not bottom supported but is designed to float. Semi-submersibl
33、es 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 relative to the seabed special equipment must be used to connect the rig to the seabed and to allow drillin
34、g 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 drilled the rig still has a lot of work to do. Some wells may require maintenance (workovers) or sidetracks
35、 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 factors, e.g. specially designed rigs, subsea equipment, loss of time due to bad weather, expensive transp
36、ort 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 DRILLING ECONOMICS,7.1 Drilling cost in field development It is quite common for drilling cost
37、to make up 25-35% of the total development costs for an offshore oilfield. 7.2 Drilling cost estimates Before a drilling program ia approved it must contain an estimate of the overall costs involved. When drilling in an completely new area with no previous drilling data available the well cost can o
38、nly 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, accommodation Depth related cost: casing, cement Fixed cost: wellhead More sophisticated methods of esti
39、mating 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 Distribution,Rank the major cost elements in the development of the Brae Field given i
40、n 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,Platform equipment, development drilling, platform structure, pipeline, pl
41、atform 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 aspects of the drilling operation and how you would drill the w
42、ell: 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 causes of instability -potential consequences of instabilit
43、y -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 evaluating the potential oil and gas production of
44、the formations e) The surface equipment requirement,47,48,Chap.2 Rig Components,Introduction Power system Hoisting system Circulating system Rotary system Well control system Well monitoring system,49,1. Introduction,Six sub-systems: the power system; the hoisting system; the circulating system; the
45、 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 then supplied to electric moto
46、rs 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: Drawworks: drum, drillin
47、g line. Crown block: Travelling block: Hook: Elevator: Deadline, fastline Deadline anchor,55,Static: Ff=Fd=W/N N is the number of lines, W is the hook load. Dynamic: Ff=W/EN; Fd=W/N E is the efficiency of the system. Output power of drawworks (load on fast line times velocity of fast line): HPd=FfVf
48、/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 is FD=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
49、crown 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 circulate 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