油田开发ProTech1PP99

Course:- 28117Class:- 289033a HERIOT-WATT UNIVERSITYDEPARTMENT OF PETROLEUM ENGINEERINGExamination for the Degree ofMEng in Petroleum EngineeringProduction Technology 1aThursday 22nd April 199909.30 - 11.30NOTES FOR CANDIDATES1.This is a Closed Book Examination and candidates are allowed to utilise course notes forreference during the exam.2.15 minutes reading time is provided from 09.15 - 09.30.3.Examination Papers will be marked anonymously. See separate instructions for completion ofScript Book front covers and attachment of loose pages. Do not write your name on any loose pages which are submitted as part of your answer.4.Candidates should attempt ALL questions.5.The marks allocated to each question are shown in brackets after the question.6.State clearly any and all assumptions you make.The Alpha oil reservoir is a small offshore field which is currently being considered for development.It is likely that the field will require 3-5 production wells. Currently the use of a small fixed jacket is preferred with the possible use of a subsea template/completion if further delineation causes a significant downsizing in reserves.The general conditions for the field are shown in Table 1 with the fluid and reservoir characteristics shown in Table 2 and 3 respectively. A projected casing schedule is shown in Table 4. Table 5 outlines the probable trajectories.It is anticipated that the well deliverability will require the use of 41/2" OD tubing. However as the wells are anticipated to be under a depletion (solution gas in late life) drive, well deliverability will decline almost immediately.Table 1 - Field Location and General DataWater depth 180 ft Location 100 miles offshore NE Scotland Adjacent existing platform is 8 miles to the SW No. of wells projected 3-5Reserve estimate 47 x 106 STB No aquiferNo gas cap at initial reservoir pressureTable 2 - Reservoir Fluid Data API Gravity = 31 degreesOil viscosity at reservoir conditions = 7 cp GOR = 420 SCF/bblH2S concentration = 5ppm CO2 concentration = 8%Bubble point of crude oil = 1800 psiaTable 3 - Reservoir DataTop of oil column = 5900 ft TVDSS Thickness of reservoir sand = 140 ft Bottom hole temperature = 180°F Permeability = 80-270 mdAverage permeability = 170mdInitial reservoir pressure = 2900 psia at 5900ft KV/KH = 1.0 (approx)The reservoir consists of a consolidated to friable, heterogeneous, fine grained sandstone with limited clay content. It is slightly overpressured and overlain by a thin (150 ft) shale layer.Table 4 - Provisional Casing ScheduleHole Size Casing Size Setting Depth (TVDSS) ft in in From To 2620Surface100017 1/213 3/8Surface260012 1/49 5/8Surface47008 1/27420059506option 1. 4 1/255006150option 2. 4 premium screenoption 3.Open holeTable 5 - Projected Well TrajectoryAll wells will have the following outline trajectory Hole Size Hole angle from vertical in section in Top Bottom260º0º17 1/20º15-25º12 1/415-25º60-65º8 1/260-65º65-80º665-80º80-90ºUse short notes and sketches to answer the following questions.State all assumptions and give reasons where possible.1.For this particular development, discuss the options for the bottomhole completion technique,namely, perforated/cemented liner; premium screen or openhole. What would you recommend and why?[15]2.What would be your concerns about the selection of a drill-in fluid for the 6 inch hole and whatfluid and additives would you recommend?[10]3.Provide a sketch of a conceptual configuration for the completion of the oil producers. Specify:a)Key components and your reasons for their selectionb)Approximate setting depths[25]4.Assuming that the wells were drilled overbalanced how would you lower the bottomholepressure to initiate flow?[10]5.If it is necessary to pull the tubing, how would you secure the well, isolate flow and kill the well?[10]6.If the reserves are downgraded and a platform is uneconomic, how would you modify yourdesign if the field were developed by a maximum of 3 subsea satellite production wells?Provide a sketch.[15]7.Propose a contingency configuration for satellite water injector completions.[10]8.If the reservoir were put on water injection, how would this impact on your design for the oilproducers?[5] End of Paper。