well production performance analysis for unconventional...

“WELL PRODUCTION PERFORMANCE

ANALYSIS FOR UNCONVENTIONAL SHALE

GAS RESERVOIRS; A CONVENTIONAL

APPROACH”

FLORIN HATEGAN

Devon Canada Corporation

BACKGROUND Shale Gas HZ Drilling, Multi-Stage Hydraulic Fracturing:

Today is the norm throughout the industry

Very High Drilling & Completion costs

Performance Evaluation “complex” and controversial

SUCCESS IS RESERVOIR SPECIFIC

FIELD ANALOGIES CAN BE DANGEREOUS

ABSTRACT CONCEPTS SUCH AS S.R.V., OR F.C.A. WRONGLY USED AS DEFINING PARAMETERS

IN-SITU RESERVOIR PARAMETERS SUCH AS PORE

PRESSURE AND PERMEABILITY ARE TO OFTEN

OVERLOOKED, OR IGNORED

PRESENTATION OVERVIEW

• Introduction

• Stimulated Reservoir Volume (SRV)

• Linear Flow Spreadsheets

• Analytical Model Construction Pseudo Steady State Equation Solution

Reservoir Pressure

Permeability or Flow Capacity

Completion Skin

Drainage Area and Shape

Field Case Examples

• NORMALIZED SHALE GAS PRODUCTION PLOT

• In-Situ Testing for D&C Optimization Field Case Example

• Conclusions

INTRODUCTION

• PERFORMANCE EVALUATION SHALE GAS PRODUCTION CAN NOT BE ANALYZED BY

CONVENTIONAL METHODS (e.g. DARCY LAW)

PRODUCTION PERFORMANCE IS MAINLY A FUNCTION OF STIMULATED RESERVOIR VOLUME (SRV)

USE OF “LINEAR FLOW” SPREADSHEETS

• CHALLENGE SHALE GAS PERFORMANCE CAN BE MODELLED ANALYTICALLY

USING PSEUDO STEADY-STATE SOLUTION

ONLY 4 (Four) KEY FORECST PARAMETERS:

Reservoir Pressure

Matrix Permeability (In-Situ)

Completion Skin

Drainage Area & Shape per Stage (correlated to Pi, k & s’)

ANALYTICAL MODEL = Superposition of Solutions for Pseudo Steady-State Equation Applied to Individual Frac Stages

Stimulated Reservoir Volume (SRV)

• The most talked about concept introduced after successful

HZ-MSF developments in the Barnett Shale and elsewhere

• Thousands of publications, articles and presentations on

this topic

• SRV may be over-rated or misunderstood

Stimulated Reservoir Volume (SRV) • Microseismic Mapping

Stimulated Reservoir Volume (SRV) • Integration of Microseismic into Reservoir Simulator


• Integration of Microseismic into Reservoir Simulator


• Integration of Microseismic into Reservoir Simulator

SRV gridding and Ksrv distribution

Stimulated Reservoir Volume (SRV) • IN-SITU SHALE GAS MATRIX CONFIGURATION:

THIN SECTION

MATRIX & NAT. FRACTURES


• IN-SITU SHALE GAS MATRIX CONFIGURATION:

THIN SECTION

MATRIX, NO NAT. FRACTURES


• MATRIX & NAT. FRACTURES • MATRIX, NO NAT. FRACTURES

Stimulated Reservoir Volume (SRV) • EVIDENCE OF SHALE MATRIX WITH NO IN-SITU NAT. FRACTURES:

Linear Flow Spreadsheets


WELL NAME HERE

0.0E+00

1.0E+06

2.0E+06

3.0E+06

4.0E+06

5.0E+06

6.0E+06

0 10 20 30 40 50

Sqrt t

dm

(p)/

q

0

100

200

300

400

500

600

700

800

900

1000

Pre

ssu

re

WELL NAME HERE

10

100

1000

10000

1 10 100 1,000 10,000

Time

Rate

Daily Production AOF EHS Test

WELL NAME HERE

10

100

1,000

10,000

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Cum (Bcf)

Rate

(M

cf/

D)

Actual Fitted tehs

WELL NAME HERE

0.0E+00

1.0E+06

2.0E+06

3.0E+06

4.0E+06

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Cum (Bcf)

dm

(p)/

q

Actual Fitted tehs

WELL NAME HERE

1.0E+04

1.0E+06

2.0E+06

3.0E+06

0 10 20 30 40 50 60

Sqrt t

dm

(p)/

q

WELL NAME HERE

1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Cum (Bcf)

q/d

m(p

)

Actual tehs


• Input Data

• Results

ANALYTICAL MODEL

CONSTRUCTION • Pseudo Steady-State Equation

General

Using Gas Pseudo-Pressure

ANALYTICAL MODEL

CONSTRUCTION

• Reservoir Pressure

Initial Reservoir Pressure (Pi) Pre-Frac Tests

Conventional FBU Tests As soon as possible after completion

Watch balance of flow time and buildup time

Requires long shut-ins (1 month +)

ANALYTICAL MODEL

CONSTRUCTION • Reservoir Pressure: 200 h Flow & 1 Mo BU

p* = 31330 kPaa

ANALYTICAL MODEL

CONSTRUCTION • In-Situ Matrix Permeability & Total Completion Skin

Most difficult to obtain

Require recalibration with early time production data

First step: km from initial FBU:

Field example: SHALE 1 HZ-MSF 9 Stages

Initial FBU Analysis: (kh)t = 1.9 mDm, s’ = - 4.41

Divide (kh)t by net pay and nr. of frac stages: km = 0.0031 mD

ANALYTICAL MODEL

CONSTRUCTION • Drainage Area and Shape

Observed Strong Correlation between k and A

ANALYTICAL MODEL

CONSTRUCTION • Drainage Area and Shape (Per Frac Stage)

APPARENT EFFECTIVE DRAINAGE AREA

Extrapolate to cover shale gas permeability range

Drainage Shape: requires more work (L:W Ratio = 3:1)

ANALYTICAL MODEL

CONSTRUCTION • ANALYTICAL MODEL = Superposition of Solutions for Pseudo

Steady-State Equation Applied to Individual Frac Stages

ANALYTICAL MODEL

CONSTRUCTION • RECALIBRATE MATRIX PERM & SKIN

km = 0.0015 mD

s’ = - 5.2

Production History

20

40

60

80

100

120

140

160

Gas (

10

3m

3/d

)

0

4000

8000

12000

16000

20000

24000

28000

Pre

ssu

re (k

Pa)

0 10 20 30 40 50 60 70 80 90

Time, days

LegendTubing Pressure

Bottom Hole Pressure

Actual Gas Data

History Match

HZ-MSF Model

0

20

40

60

80

100

120

140

160

180R

ate

(10

3m

3/d

)

0

5000

10000

15000

20000

25000

30000

Pre

ssu

re (k

Pa)

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

Time (d)

LegendFlow Press

Gas Rate

Syn Res Press, P is calculated

Syn Flow Press

ANALYTICAL MODEL

CONSTRUCTION • ANALYTICAL MODEL (UPDATE):

ANALYTICAL MODEL

CONSTRUCTION • ANALYTICAL MODEL & PRODUCTION UPDATE

ANALYTICAL MODEL • ANALYTICAL MODELS & PRODUCTION UPDATES:

ANALYTICAL MODEL • BARNETT SHALE Example

SHALE GAS • SHALE GAS MODELS USING PSEUDO STEADY STATE SOLUTION

NORMALIZED SHALE GAS PRODUCTION

• SHALE GAS NORMALIZED PRODUCTION PLOT :

DIVIDE TOTAL WELL PRODUCTION RATE BY:

Nr. Frac Stages (n)

Initial Pressure (Pi)

Flow Capacity (kh)



Nr. Frac Stages (n), Initial Pressure (Pi) and Flow Capacity (kh)

NORMALIZED SHALE GAS PRODUCTION • SHALE GAS NORMALIZED PRODUCTION PLOT :


IN-SITU SHALE GAS TESTING

• Several Testing Techniques Are Used To Test

Shale Gas Formations Prior Completion:

Diagnostic Fracture Injection Test (DFIT)

Wireline Formation Tests (RFT, MDT, CHDT…)

Perforation Inflow Diagnostic (PID)

IN-SITU SHALE GAS TESTING • SHALE GAS PID TESTING:

FIELD EXAMPLE (SHALE 1 – Vertical Well)

IN-SITU SHALE GAS TESTING • SHALE GAS PID TESTING: D&C OPTIMIZATION

CONCLUSIONS 1. Shale gas HZ-MSF well performance can be derived

using simple, “conventional” analytical models.

2. In-situ shale gas reservoir properties (Pi & k) and

shale “fabric” (presence of natural fractures) will

control the production performance of HZ-MSF wells

3. Misinterpretations of SRV will account for significant

overestimations of long-term cumulative production

4. HZ-MSF has a cumulative effect on well production by

adding in-situ FLOW CAPACITY and not by

“CREATING” better reservoir on a large areal extent

5. NORMALIZED PRODUCTION PER FRAC STAGE IS

ONE OF THE BEST TOOLS FOR D&C OPTIMIZATION

6. Pi & k for shale gas can be obtained using PID testing.

THANK YOU!

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