Surface Modeling Vs Downhole Modeling

Transcription

1 Gas Well Deliquification Workshop Sheraton Hotel, February 23-26, 2009 Surface Modeling Vs Downhole Modeling Jose M Macias, Technical Manager Gas Treatment, Champion Technologies

2 Overview Modeling in Prediction of Foam Assisted Lift Turner and Coleman Equation was based on surface data. Correlation between Well Simulation and Coleman Equation Field Application of Surface Data Down hole Modeling using ULL and Pipesim Correlations Field Application of Down hole Simulation 2

3 Coleman Simulation Well Simulator Coleman Equation used to predict critical rate. Correlation between Well Simulation and Coleman Equation Critical Rate Transition out of annular flow. Flow Maps in Simulators show that for all IDs tested the critical rate is transition to wavy annular 3

4 Coleman Simulation Transition based on Gas velocity but can be affected by liquid velocity Liquid velocity dependent on mass flow. 4

5 Coleman Simulation Critical Lift Concentration Concentration required to have a net positive movement of all fluids introduced into a well bore. Drastically dependent on gas flow in relation to liquid flow. 5

6 Surface Modeling Monitoring of well performanc e over time. Allows for decision about critical lift concentrati on based on well simulation. 6

7 Surface Modeling Case History 40 Wells at various stages of loading were modeled over a month period. Based on well simulation critical lift concentration was determined and surfactant dosage and application type was determined. After initial application based on surface modeling, wells were reviewed based on production graphs. 80% of wells initial treatment and dosage was determined to be successful. 7

8 Success Criteria Success dependent on production graphs. Stabilization on production. Increased production. Overtime (before and after treatment) 8

9 Surface Modeling Case History Application Type and dosage determined by surface data. Application Type Application Rate % Below Critical Average (% Condensate) Review Daily Cycle Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Continuous Semi-Batch and Continuous Continuous Semi-Batch and Continuous Semi Batch Semi-Batch and Continuous Continuous Semi-Batch and Continuous Semi Batch Semi-Batch and Continuous Continuous Semi-Batch and Continuous Semi Batch Semi-Batch and Continuous Continuous Semi-Batch and Continuous Semi Batch Semi-Batch and Continuous Continuous Semi-Batch and Continuous Semi Batch Semi-Batch and Continuous Continuous Semi-Batch and Continuous Semi Batch Semi-Batch and Continuous Continuous Semi-Batch and Continuous Semi Batch Batch and Continous Continuous Batch and Continous Batch Batch and Continous Continuous Batch and Continous Batch Batch Shut In and Continuous Continuous Batch Shut In and Continuous Batch Batch Shut In and Continuous Continuous Batch Shut In and Continuous Batch Batch Shut In Review Batch Batch Shut In Review Batch Batch Shut In Review Batch Batch Shut In Review Batch Batch Shut In Review Batch Batch Shut In Review Batch Batch Shut In Review Batch Batch Shut In Review Batch Batch Shut In Review Batch Batch Shut In Review Batch Batch Shut In Review Batch Batch Shut In Review Batch

10 Downhole Modeling Downhole Modeling Required for Cases when surface modeling cannot predict loading. Downhole modeling allows for prediction of transition out of annular flow in the tubing. Transition out of annular flow is indication of liquid loading. 10

11 Downhole Modeling Various models and correlations available for down hole modeling. ULL Gas Well and Pipesim used for prediction of down hole transition as well as fluid location. Down hole modeling allows for application determination. 11

12 Down hole Modeling Case History From the 8 wells that did not respond to surface model predictions and application, 5 fell into severely loaded category and 3 fell into loaded down hole category. The 5 that were severely loaded responded to a larger batch application. 3 Wells that were predicted to be close to critical production showed loading in the tubing by down hole modeling. 12

13 ULL Flow Regime Profile 13

14 ULL Output 14

15 Models and Preference Pipesim Model is most robust but data not always available. ULL Dependent on Water Analysis and Gas Analysis Bottomhole Pressure Is Most Critical and can cause differences in correlations. 15

16 Down hole Modeling Case History Dosage rate was adjusted based on the down hole predictions and wells responded. Well simulation and surface modeling did not correlate and provide good treatment recommendation. 16

17 Surface vs Downhole modeling Surface modeling allows for analysis of a dynamic range of data. Can be used in conjunction with critical lift concentration curves to determine the dosage rate and application technique. If Coleman or Turner correlations did not encompass the type of down hole loading that is occurring in a well then predictions will be erroneous. 17

18 Surface vs Down hole Modeling Down hole modeling allows for accurate prediction of liquid loading and estimates location of loading. Down hole modeling can be done only in a snap shot approach. Application of surface modeling for initial assessment of well loading followed by more detailed down hole modeling proved a good technique for case study. 18

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