Pratik Rao - Thesis Presentation FINAL

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<ul><li><p>eni Ss.p.aA. upstream &amp; technical services </p><p>2014-2015 Master in Petroleum Engineering and Operations </p><p>Well Testing for Reservoir Management: A Case Study </p><p>Author: Pratik Nityanand Rao </p><p> San Donato Milanese 15 October 2015 </p></li><li><p>2 </p><p> Well Testing for Reservoir Management: </p><p>A Case Study </p><p>San Donato Milanese 15 October 2015 </p><p>Author </p><p>Pratik Nityanand Rao </p><p>Division eni S.p.A. </p><p> Upstream &amp; Technical Services </p><p>Dept. RESM </p><p>Company Tutors </p><p>Enzo Beretta </p><p>Giuseppe Tripaldi </p><p>University Tutor </p><p>Prof. Francesca Verga </p><p>Master in Petroleum Engineering &amp; Operations 2014-2015 </p></li><li><p>3 </p><p> Project Background </p><p> Discussion of the Case Study </p><p> Conclusions </p><p>List of Contents </p><p> Well Testing for Reservoir Management: </p><p>A Case Study </p></li><li><p>4 </p><p>Project Scope </p><p> To verify when the well testing interpretation of permanent </p><p>gauges is feasible and helpful for reservoir monitoring. </p><p> To provide a preliminary field characterisation for the case study. </p></li><li><p>Considered Points </p><p>5 </p><p> Interference from nearby wells </p><p> Inadequate build-up and drawdown durations </p><p> Complex model </p></li><li><p>Interference from Nearby Wells </p><p>6 </p><p>Drawdown Build-Up </p><p> Drawdown interpretation is usually </p><p>more reliable because each well </p><p>defends its drainage area </p><p> Build-up late time models are </p><p>usually disturbed by interference </p><p>from nearby wells </p><p>Shut-in well </p><p>Open well </p><p>Drainage area defended </p><p>Drainage area encroached </p></li><li><p>Build-Up and Drawdown Durations: Standard Approach </p><p>7 </p><p>IARF (before reaching </p><p>boundaries) </p><p>Drawdown </p><p>(slope = 1) </p><p>Build-up </p><p>(reservoir </p><p>pressure </p><p>stabilises) </p><p>Sealing Barrier </p><p>Duration of radial flow is a function </p><p>of well location inside the reservoir </p></li><li><p>Build-Up and Drawdown Durations: Alternative Approach </p><p>8 </p><p>IARF (before reaching </p><p>boundaries) </p><p>Sealing Barrier </p><p>Duration of radial flow is a function </p><p>of well location inside the reservoir </p></li><li><p>9 </p><p>Alternative Approach Workflow C</p><p>on</p><p>str</p><p>ain</p><p>t </p><p>Start! </p><p>Using log-log plot, match early and middle time models. </p><p>Set Initial Reservoir Pressure (from WFT/RFT). </p><p>STEP</p><p> 2 </p><p>Run sensitivities on boundary distances to match the pressure history. </p><p>STEP</p><p> 1 </p></li><li><p>10 </p><p>Complex Model </p><p>Analytical models are inadequate for matching in a single step </p><p>Step 1: Early + Middle time for estimation of wellbore and bulk reservoir properties. </p><p>Step 2: Middle + Late time for estimation of boundary distances. </p><p>Note: The two sub-models have to be consistent with the reservoir outer permeability because it is present in the middle time model, which is used in both steps 1 and 2. </p><p>Late Middle Early </p></li><li><p>11 </p><p>List of Contents </p><p> Well Testing for Reservoir Management: </p><p>A Case Study </p><p> Project Background </p><p> Discussion of the Case Study </p><p> Conclusions </p></li><li><p>12 </p><p>Well A Data </p><p>Gauge depth 2752 m TVDSS </p><p>Well Type Horizontal </p><p>Horiz. Net Length 200 m </p><p>Completion 7 5 ; Gravel Pack </p><p>General Information of the Field </p><p>A </p><p>B </p><p>2.7 km </p><p>Well B Data </p><p>Gauge depth 2753 m TVDSS </p><p>Well Type Horizontal </p><p>Horiz. Net Length 130 m </p><p>Completion 7 5 ; Gravel Pack </p><p>Reservoir &amp; Fluid Data </p><p>Initial Reservoir </p><p>Pressure </p><p>372.9 bar </p><p>@ Gauge Depth </p><p>Lithotype Sandstone </p><p>Net pay 14 m </p><p>Porosity 23% </p><p>Fluid Type Wet Gas </p><p>CGR </p><p>15 bbl/MMscf </p><p>(0.000087) </p><p>STm3/Sm3 </p><p>Specific </p><p>Gas Gravity 0.69 </p><p>Gas FVF 0.0036 Rm3/m3 </p><p>Gas Viscosity 0.029 cP </p><p>Total </p><p>Compressibility 1E-4 bar-1 </p></li><li><p>Production History (1/2) </p><p>13 </p><p>Field Production for Well A Alternating Production </p><p>for Wells A &amp; B </p><p>Field </p><p>Rate </p><p>Well A BHP Well B BHP </p></li><li><p>Production History (2/2) </p><p>14 </p><p>Field </p><p>Rate </p><p>Well A BHP </p><p>Well B BHP </p></li><li><p>Build-Ups Comparison for Well A </p><p>15 </p><p>Build-up from 05/10/2012 (~103 days) Build-up from 19/01/2013 (~39 days) Build-up from 09/03/2013 (~220 days) </p></li><li><p>Horner Match </p><p>Log-Log Match </p><p>Pressure History Match </p><p>Interpretation Model </p><p>Step 1: Well A Radial Composite Match </p><p>16 </p><p> Early Time: Wellbore Storage &amp; Skin </p><p>Middle Time: Radial Composite </p><p> Late Time: Infinite Lateral Extent </p><p>Analysed </p><p>build-up </p><p>period </p></li><li><p>Well A Radial Composite Output </p><p>17 </p><p>Inner Flow Capacity 2750 mD.m </p><p>Inner Permeability 200 mD </p><p>Outer Flow Capacity 560 mD.m </p><p>Outer Permeability 40 mD </p><p>Well Skin* -3.60 </p><p>Total Skin -7.20 </p><p>Interface Radius 350 m </p><p>Storativity Ratio 1 </p><p>Mobility Ratio 5 </p><p>Investigation Radius 3260 m </p><p>(*) The skin cannot be sub-divided into its components </p><p>(mechanical, geometrical and turbulence) because at </p><p>the horizontal well, the early time cannot be recognised </p><p>on the derivative plot. </p></li><li><p>Horner Match </p><p>Log-Log Match </p><p>Pressure History Match </p><p>Interpretation Model </p><p>Step 2: Well A Closed System Match </p><p>18 </p><p> Early Time: Wellbore Storage &amp; Skin </p><p>Middle Time: Homogeneous (outer kh) </p><p> Late Time: Closed Rectangle </p><p>Analysed </p><p>build-up </p><p>period </p></li><li><p>Well A Closed System Output </p><p>19 </p><p>Gauge Depth 2752 m TVDSS </p><p>Initial Reservoir Pressure 372.9 bar </p><p>Initial Fluid Regime 1.36 bar/10m </p><p>Average Reservoir Pressure 348 bar </p><p>Average Fluid Regime 1.27 bar/10m </p><p>Depletion 25 bar </p><p>Distance (+x) 860 m </p><p>Distance (+y) 2300 m </p><p>Distance (-x) 1300 m </p><p>Distance (-y) 5750 m </p><p>Area 17.40 km2 </p></li><li><p>Well A Closed System Validation </p><p>20 </p><p>Reservoir Area = 17.40 km2 </p></li><li><p>Preliminary Estimate of the GOIP </p><p>21 </p><p>Gas Originally In Place (GOIP) = 14.40 GSm3 </p></li><li><p>GOIP from Geologists Method </p><p>22 </p><p> Area = 17.40 km2 = 17,400,000 m </p><p> Net Pay = 14 m (Net-to-gross ratio already factored in) </p><p> Porosity (f) = 0.23 </p><p> Irreducible Water Saturation (Swi) = 0.1 </p><p> Gas Formation Volume Factor (FVF) = 0.0036 Rm3 / m3 </p><p>Gas Originally In Place (GOIP) = 14.00 GSm3 </p><p> Area * Net Pay * f * (1- Swi) GOIP = ---------------------------------------------- FVF </p></li><li><p>23 </p><p>List of Contents </p><p> Well Testing for Reservoir Management: </p><p>A Case Study </p><p> Project Background </p><p> Discussion of the Case Study </p><p> Conclusions </p></li><li><p>24 </p><p>Conclusions (1/2) </p><p>CONSIDERED POINTS </p><p>SOLUTIONS APPLICATION ON THE CASE STUDY </p><p>Interference from nearby wells </p><p>To exploit long drawdown acquisition (at constant rate) </p><p>Well testing interpretation was performed on data that was unaffected by interference </p><p>Inadequate build-up and drawdown durations </p><p>Alternative workflow based on pressure matching needs: Reliable initial pressure from WFT/RFT At least one build-up acquisition </p><p>Applied </p><p>Complex model 1. Divide in sub-models 2. Numerical well </p><p>testing software Option 1 applied </p></li><li><p>Conclusions (2/2) </p><p>25 </p><p> The standard approach for build-up and drawdown interpretation </p><p>cannot be applied to this case study </p><p> The reservoir pressure at gauge depth (2752 m TVDss) after 0.6 </p><p>GSm3 of cumulative production resulted to be 348 bar, with a </p><p>corresponding depletion of about 25 bar </p><p> The average effective gas permeability for Well A was 40 mD </p><p> The skin was about -4, which indicates that the well is not damaged </p><p> The skin cannot be sub-divided into its components (mechanical, </p><p>geometric and turbulence) because at the horizontal well, early time </p><p>cannot be recognised on the derivative plot </p><p> The preliminary estimate of GOIP was 14.40 GSm3 (after cumulative </p><p>production of 0.6 GSm3) </p></li><li><p>26 </p><p>Acknowledgements </p><p>I would like to thank the Management of Eni </p><p>Upstream and Technical Services for permission to </p><p>present this work &amp; related results, and RESM </p><p>colleagues for the technical support &amp; needed </p><p>assistance. </p><p>San Donato Milanese 15 October 2015 </p></li></ul>