Stimulation - New Mexico Institute of Mining and Technologyinfohost.nmt.edu/~petro/faculty/Engler571/Stimulation-1.pdf · Stimulation Design ©Copyright Thomas W. Engler, Ph.D, P.E.

Stimulation Design

©Copyright

Thomas W. Engler, Ph.D, P.E.

Stimulation Introduction

• A restriction to flow occurs around the wellbore or in the reservoir

• Stimulation is a means to improve productivity by reducing/eliminating this restriction.

First step: identify restriction, e.g. perfs, reservoir, gravel pack…, fines, clays, paraffins

Second step: select and design appropriate treatment to improve productivity.

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Why Stimulation?

Stimulation Introduction

• Flow equation:

• Of primary importance:

increase permeability and/or reduce skin

• Skin is multicomponent!

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How to improve production?

Swr

eroBo

wfprpkhoq

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)(

Stimulation Introduction

• Perforating – increase area open to flow through the completion

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Methods to consider:

(Golan and Whitson, 1991)

Stimulation Introduction

• Matrix acidizing – reduce large skin resulting from near-wellbore permeability damage due to completion/drilling operations.

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Methods to consider:

Stimulation Introduction

• Hydraulic fracturing – increase the effective wellbore radius by creating an increase in contact area between well and reservoir.

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Methods to consider:

Simplified diagram of equipment for hydraulic fracturing (Veatch, Jr., 1983)

Stimulation Introduction

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0 50 100 150 2000

500

1000

1500

2000

2500

Liquid Rate, Bbl/D

Pre

ss

ure

, p

sig

Inflow @ Sandface (1) Not Used

Inflow (1) Outflow (A)

Case 2 (2) Case 2 (B)

Case 3 (3) Case 3 (C)

Not Used Not Used

Not Used Not Used

Not Used Not Used

Not Used

1A

1 2 3

Inflow

Inflow

Perforation Shot Density, SPF

(1) 2.0

(2) 4.0

(3) 8.0

Effect of Perforation Density on Well Performance

How to improve production?

Stimulation Introduction

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0 100 200 300 4000

500

1000

1500

2000

2500

Liquid Rate, Bbl/D

Pre

ss

ure

, p

sig

Inflow @ Sandface (1) Not Used

Inflow (1) Outflow (A)

Case 2 (2) Case 2 (B)

Case 3 (3) Case 3 (C)

Not Used Not Used

Not Used Not Used

Not Used Not Used

Not Used

1

A

1 2 3

Inflow

Inflow

Reservoir Skin

(1) 3.000

(2) 0.000

(3) -3.000

Effect of Damage and Stimulation on Well Performance

How to improve production?

Stimulation Introduction

(1890) to (1950) – openhole completions, typical stimulation was liquid or solid nitroglycerin. Hazardous, but successful. ZEro hour Bombing CO.

(1895) – first acid treatment, 65 bbls of HCl pumped in Ohio Oil Company’s Crosley

Farm lease in Lima, Ohio. Oil increase 300%. (1932) – 500 gal of HCl w/arsenic inhibitor in a wooden tank(3’ dia x 12’ long) on a

wagon. Transferred to well by siphoning through a garden hose. Displaced with oil. Dead to 16 bopd. Pure Oil Co. (Amoco), Fox No. 6 in Michigan by Dow Chemical Co. Aka Dowell

(1935) – Halliburton Oilwell Cementing Co. expanded into stimulation. (1947) – first hydraulic fracture treatment. Western Kansas in Hugoton Basin, Klepper

No. 1. Four gas productive limestone pays (3-perf zones,1-OH). 1000 gals of Gasoline-based, napalm-gelled fracturing fluid followed by 2000 gals of gasoline + breaker per zone. Through tubing with cup-type straddle packers. Due to fire hazard all units were 150 ft. apart. Deliverability unchanged!

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History

Stimulation Introduction

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History

Stimulation Introduction

(1945) to (1963) – development of acid-fracturing techniques

(Early 1970s) – introduction of foamed frac treatments.

(1990s) – fracturing of horizontal wells, coiled tubing acidizing

(2000s) – microseismogram monitoring

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History

More complex

configuration?

Courtesy of Devon

-3000

-2500

-2000

-1500

-1000

-500

0

500

1000

1500

-1000 -500 0 500 1000 1500 2000 2500 3000

West-East (ft)

So

uth

-No

rth

(ft

)

Well A

Well B

Well C

Well D

Well E

Monitor

Well

Frac

Well

FRACTURE DIAGNOSTICS -

MICROSEISMIC

Stimulation Introduction

.…today

Stimulation Introduction

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.…today

Picture courtesy of Halliburton

Stimulation Introduction

© Copyright, 2011

.…today

Stimulation Introduction

© Copyright, 2011

.…today

Picture courtesy of Halliburton

Stimulation Introduction

• fracturing has made a significant contribution in enhancing production rates and reserves.

• 35 to 40% of all currently drilled wells are fractured

• accounting for 25 to 30% of U.S. reserves (8 billion bbls).

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Success

0%

10%

20%

30%

40%

Perc

en

t o

f

Resp

on

ses

< 25% 25-50% 50-75% > 75%

Frequency

sandstone

66%

carbonate

26%

coal

5%

other

3%

Percent of wells hydraulically fractured Fracture treatment zone lithology

Source: GRI, 1992