Joint Industry Project on Deliquification

Transcription

1 on Deliquification Predicting the gains for European wells Jordy de Boer Erik Nennie

2 2 Project structure and goals Overall goal: Transfer US knowledge on deliquification to Europe Three phases: 1. Literature search What techniques are applied, and how widely Many common techniques in the US are not applied in Europe 2. Engineering guidelines to predict most suitable technology Implemented as Excel-based tool 3. Quantitative tool Calculate benefits of various technologies Can serve as input to economic screening process

3 3 Need for quantitative analysis Selection methodology yields candidate technologies Based on well depth, deviation, LGR, etc Actual deployment decision is a balance between: Production and UR gain over time CAPEX/OPEX TNO s expertise lies in modelling Models were implement for a range of techniques Implemented in a GUI for quick screening Calculates modified production profile after implementing each technology CAPEX/OPEX analysis left to operator

4 4 Technologies included in the tool Allow the operator to evaluate the benefit of using Velocity string ESP Foam Plunger Wellhead compression Gas lift Eductor Performance measured by Ultimate recovery / abandonment pressure Production profile and required power over time

5 5 Methodology Basic wellbore and reservoir model required Wellbore model calculates BHP Reservoir model Simulates depletion Includes reservoir pressure drop Semi-steady state models describing each technique Goal: translate technique to modified well lift performance Reservoir model is not modified

6 6 Wellbore modelling Correlation required to calculate wellbore dp Deviated wells Variable diameter Many correlations are proprietary, choice was limited Gray standard Gray does not handle deviated wells Beggs and Brill universal OLGA ss proprietary Beggs and Brill was chosen Good match with OLGA Inclinations from horizontal to vertical

7 7 Reservoir modelling Tank (material balance model): With re reservoir drainage radius, and ϕ porosity Pressure drop is modelled using A and F factors: A, F can be calculated from reservoir parameters Ideally should be known from well tests

8 BHP 8 Base modelling method Line P Choke assumed open Beggs and Brill: tubing TPC at constant WHP Reservoir IPR calculated, including depletion Operation point continuously calculated Loading occurs at TPC minimum End of production Yields abandonment pressure WHP Depletion Tubing TPC Loading Gas flow

9 BHP 9 Modelling mitigation measures Mitigations modelled in different ways Completion (diameter) change: Velocity string Tailpipe Change in boundary condition: Eductor: performance diagrams Wellhead compression: simplified analytical model Other models: V string loading Gas lift BHP is minimized, staying within available power Tubing loading Gas prod ESP liquids are produced by pump through separate string V string TPC Tubing TPC

10 10 Modelling: foamer Line P Assumed to be added continuously Start-up not taken into account Cap-string type of application Foaming mechanism is complex Reduction in surface tension Reduces critical rate to 75% of original rate Foam formation Increases gas-liquid surface area Reduced density, improved liquid transport Further reduction in critical rate to 50% or less Full modelling not feasible Reduction in critical rate is input to the tool WHP Choke assumed open

11 BHP 11 Modelling: plunger lift Line P Choke assumed open Most effective in smaller tubing (up to 3.5 ) Usually requires installation of new tubing Most effective when annulus pressure buildup possible Low-set downhole packer is unfavourable Production is first assumed to occur through small string When close to loading, plunger installed (see below) WHP Smaller string TPC Plunger TPC Tubing TPC Tubing loading Gas prod

12 P [bar] 12 Lea plunger lift model (1999) Method developed to compare plunger to velocity strings Calculates a TPC for the plunger lift system Assumptions: Gas influx constant throughout cycle Plunger rise velocity 5 m/s No slip past plunger Example cycle: Slug size 0.05 P c,max Casing top Casing bottom Avg BHP - dyn Based on modified Foss-Gaul guidelines 10 8 Buildup P c,min Rise Blow down Final flow t [s]

13 Cumulative gas production [10 6 Nm 3 ] Cumulative gas production Tool output for 4.5 deviated well No mitigation Velocity string WHC Foam Eductor ESP Gaslift Time [yr]

14 14 Conclusions Tool was developed to predict performance of mitigation measures Based on (semi) steady state models Beggs & Brill pressure drop correlation Reservoir depletion and pressure drop Compressor, pump and eductor models Simplified plunger and foam modelling Performance was considered realistic for most wells Beggs & Brill seems less suitable for specific cases LGR >> 100 Larger diameter wells (>4 ) May be solved by implementing different correlations

15 15 Outlook for a follow-up programme Better match in cases where current models are unreliable Further validation against field trials Integrating other common pressure drop correlations Adding additional functionality Improved pseudo-pressure reservoir model Better modelling of first phase of production (e.g. by including a choke model) Intermittent production requires more advanced modelling Coupled dynamic well and reservoir model Models available, but not readily integrated in fast tool We are looking for participants to a second phase of this JIP Conditions will be discussed with current participants

16 16 Flow Assurance Course for Flowlines and Wells Date: April 14 17, 2013 Location: TNO, Delft Fundamentals of multiphase flow in flowlines and wellbores Practical Flow Assurance Multiphase dynamics: liquid loading, slug flow Solid deposition, integrity, heavy oil Well control, reservoir inflow Exercises Liquid hold-up in pipelines, severe slugging, slug catcher sizing, etc. Presenters: Prof. René Oliemans (Emeritus, TU Delft) Prof. Ruud Henkes (TU Delft / Shell Global Solutions) TNO Fluid Dynamics To keep updated, contact presenter More details and registration at

17 17 Presenter details TNO Fluid Dynamics Department, Delft, NL T: E: