# Decline Curve Analysis Using Type Curves —

## Presentation on theme: "Decline Curve Analysis Using Type Curves —"— Presentation transcript:

Decline Curve Analysis Using Type Curves —
SPE 71517 Decline Curve Analysis Using Type Curves — Evaluation of Well Performance Behavior in a Multiwell Reservoir System T. Marhaendrajana, Schlumberger T.A. Blasingame, Texas A&M U. SPE Well Performance Behavior in a Multiwell Reservoir System

 Validation using a numerical simulator
Outline  Motivation  Objectives  Multiwell model  Model assumptions  Validation using a numerical simulator  Decline type curve analysis  Methodology  Validation using a numerical simulator  Field application (Arun Field, Indonesia)  Conclusions SPE Well Performance Behavior in a Multiwell Reservoir System

A Typical p/z Plot in Arun Field (Well A-015)
Note that the well interference causes the data to deviate from the "p/z" straight line. SPE Well Performance Behavior in a Multiwell Reservoir System

Decline Type Curve Analysis (Well A-015)
Note that the late time data show well interference effects. SPE Well Performance Behavior in a Multiwell Reservoir System

p/z Plot for Arun Field (Total Field Performance)
SPE Well Performance Behavior in a Multiwell Reservoir System

 To develop an analytical solution for a multiwell system
Objectives  To develop an analytical solution for a multiwell system  Correctly models all flow regimes  Completely general formulation (constant rate, constant pressure, variable rate/pressure)  To develop a method for the analysis of production data from a multiwell system  Estimate the original oil/gas-in-place  Estimate the local flow capacity (permeability- thickness product) SPE Well Performance Behavior in a Multiwell Reservoir System

Multiwell Model — Model Assumptions
 A bounded rectangular reservoir  Homogeneous  Isotropic  Uniform thickness  Multiple vertical wells produce at arbitrary prescribed pressures (or rates) which are functions of time SPE Well Performance Behavior in a Multiwell Reservoir System

Multiwell Model — Data Used for Validation
 Homogeneous bounded square reservoir with nine producing wells.  Bottomhole flowing pressure is arbitrary for each well and is function of time. SPE Well Performance Behavior in a Multiwell Reservoir System

Multiwell Model — Validation
SPE Well Performance Behavior in a Multiwell Reservoir System

Analytical Solution Matches Numerical Solution
Initial pwf Variable pwf Final pwf Oil Rate, STB/D Well [1,2] Time, Days SPE Well Performance Behavior in a Multiwell Reservoir System

c(t) becomes constant at long times
Decline Type Curve Analysis — Methodology Production Data (Pressure & Rate) c(t) becomes constant at long times Total Material Balance Time  Results from this work:  A general formulation of the "Arp's Exponential Decline."  A single well decline type curve can be used to analyze a well performance in a multiwell system. SPE Well Performance Behavior in a Multiwell Reservoir System

Decline Type Curve Analysis — Methodology
SPE Well Performance Behavior in a Multiwell Reservoir System

Homogeneous Reservoir Example (Oil Case)
 Homogeneous bounded square reservoir with nine producing wells.  Bottomhole flowing pressure is arbitrary for each well and is function of time. SPE Well Performance Behavior in a Multiwell Reservoir System

Homogeneous Reservoir Example (Oil Case)
The performance data for all 9 wells are shown on this plot. SPE Well Performance Behavior in a Multiwell Reservoir System

Homogeneous Reservoir Example (Oil Case)
Comparison of single and multiwell analysis. SPE Well Performance Behavior in a Multiwell Reservoir System

Homogeneous Reservoir Example (Gas Case)
SPE Well Performance Behavior in a Multiwell Reservoir System

Regionally Heterogeneous Reservoir Example
 Can we analyze multiwell performance?  Accuracy of results?  In-place volume  kh product  Uniqueness of the analysis? SPE Well Performance Behavior in a Multiwell Reservoir System

Regionally Heterogeneous Reservoir Example
Material Balance Trend Decreasing Permeability SPE Well Performance Behavior in a Multiwell Reservoir System

Regionally Heterogeneous Reservoir Example
Multiwell analysis for a regionally heterogeneous oil case — this example confirms the viability of the approach. SPE Well Performance Behavior in a Multiwell Reservoir System

Regionally Heterogeneous Reservoir Example
Well k, calc. (md) k, input (md) [3,1] [3,2] [3,3] [ 20 mD ] [1,1] 22.7 22.7 25 [1,2] 5.1 5.0 [2,1] [2,2] [2,3] [1,3] 10.1 10 [ 15 mD ] [2,1] 5.1 5.0 [2,2] 9.8 10 [1,1] [1,2] [1,3] [2,3] 13.8 15 [3,1] 9.9 10 [ 25 mD ] [ 5 mD ] [ 10 mD ] [3,2] 14.2 15 [3,3] 18.9 20 OOIP (Input) 4,278 MMSTB OOIP (Calc.) 4,278 MMSTB SPE Well Performance Behavior in a Multiwell Reservoir System

Randomly Heterogeneous Reservoir Example
 Can we analyze multiwell performance?  Accuracy of results?  In-place volume  kh product  Uniqueness of the analysis? SPE Well Performance Behavior in a Multiwell Reservoir System

Randomly Heterogeneous Reservoir Example
Multiwell analysis for a randomly heterogeneous oil case — note that even this extreme case works very well. SPE Well Performance Behavior in a Multiwell Reservoir System

Regionally Heterogeneous Reservoir Example
Well k, calc. (md) k, input [1,1] [3,3] 4.04 3.64 4.10 3.73 OOIP (Input) 4,278 MMSTB OOIP (Calc.) 4,278 MMSTB Results: Observations:  Individual well performance appears to be "homogeneous"  Computed in-place volume is essentially exact  Computed permeability represents harmonic average in "well drainage area" SPE Well Performance Behavior in a Multiwell Reservoir System

N General Information — Arun Field (Indonesia) Arun Field
Located in Northern part of Sumatra, Indonesia Retrograde gas reservoir One of the largest gas fields in the world Arun Field has 111 wells: 79 producers 11 injectors 4 observation wells 17 wells have been abandoned Field Description Ø N SPE Well Performance Behavior in a Multiwell Reservoir System

Production Data Analysis: Arun Field
Selected wells for production data analysis: Well A-037  Well A-016 Well A-032  Well A-035 Well A-024  Well A-017 Well A-029  Well A-028 Well A-015  Well A-041 Well A-034 Expected results using multiwell analysis approach: Local kh product of the individual well Total field fluid-in-place SPE Well Performance Behavior in a Multiwell Reservoir System

Arun Well A-015 — Production History
Good rate and pressure history. SPE Well Performance Behavior in a Multiwell Reservoir System

Arun Well A-015 — Decline Type Curve Plot
Arun Well A-015 — very good agreement of data and model. SPE Well Performance Behavior in a Multiwell Reservoir System

All Selected Wells — Log-Log Plot
SPE Well Performance Behavior in a Multiwell Reservoir System

All Selected Wells — Decline Type Curve Plot
Good agreement of all data with single well model — validates concept. Note — data functions are not edited (raw data stream). SPE Well Performance Behavior in a Multiwell Reservoir System

Summary of Results Result from a numerical study ( JPT, June 1983), OGIP = 17.1 TCF Production History: (As of November 1998) Cumulative gas production (gross) = TCF Cumulative gas reinjected = 5.2 TCF Net cumulative gas production = = 16.1 TCF Monthly gas production (Nov. 1998) = 50 BCF (0.6 TCF/yr) SPE Well Performance Behavior in a Multiwell Reservoir System

Developed a general multiwell solution
Conclusions Developed a general multiwell solution Accurate Provide mechanism for the analysis of production data from a single well in a multiwell system Developed a methodology for the analysis of production data from an individual well in a multiwell system Can estimate original fluid-in-place (total system) and the regional permeability Can be applied for both oil and gas reservoirs SPE Well Performance Behavior in a Multiwell Reservoir System

Conclusions (Continued)
Developed a total material balance time Preserves the uniqueness of the reservoir volume Allows use of the single well decline type curve (i.e., the Fetkovich/McCray type curve) Successfully validated our work (both the analytical solution and the data analysis method) using numerical simulation Successfully demonstrated the application of our method for Arun Field (Indonesia) SPE Well Performance Behavior in a Multiwell Reservoir System

Decline Curve Analysis Using Type Curves —
SPE 71517 Decline Curve Analysis Using Type Curves — Evaluation of Well Performance Behavior in a Multiwell Reservoir System T. Marhaendrajana, Schlumberger T.A. Blasingame, Texas A&M U. SPE Well Performance Behavior in a Multiwell Reservoir System