foam injection via capillary string in vicksburg dry …...gas well deliquification workshop...

Gas Well Deliquification Workshop

Sheraton Hotel, Denver, Colorado

February 17 – 20, 2013

Foam Injection Via Capillary String in Vicksburg Dry Gas Wells in South Texas

Adam Pittman, Brent Jackson, Andrea Jimenez,

Dave Senneway

Shell South Texas Production Operations

Outline

• Background

• South Texas History

• South Texas Foam Capillary String Process

• Example Wells

• Key Learnings and Conclusions

2013 Gas Well Deliquification Workshop

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Feb. 17 – 20, 2013 2

Feb. 17 – 20, 2013


Denver, Colorado

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Foamer Background

What Does

Foam Do For

Us?

• Decrease

Surface

Tension

• Lowers Fluid

Density

• Lowers

critical gas

flow rate - lift

liquids at

lower flow

rate

Time

Prod

uctio

n

Intermittent production

Onset of liquid loading

South Texas Vicksburg Background

SOUTH TEXAS Gulf

of Mexico

Houston

Corpus Christi

Houston

Corpus Christi

Vicksburg Frio

South Texas Asset

• First wells drilled

in 1950’s

• Asset divested in

2011

• 550 Producing

wells

• 150 with Foam

Injection


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Subsurface Background

• Vicksburg and Frio were primary reservoirs

– Tight sandstones (0.1-50 mD perm)

– Dry – Wet gas (0-30 bbl/mmcf condensate)

• Reservoirs also contained water (up to 250

bbl/mmcf depending on the well)

– Typically 30-50 bbl/mmcf

– Salinity ranged from 8000 ppm chlorides to 90,000 ppm

or greater

• Very little H2S or CO2

• No requirement for SCSSV’s


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Feb. 17 – 20, 2013 5

Typical Tubingless Well Design – With Capillary String Installed

• 2-7/8” or 3-

1/2” casing

with no tubing

• Stacked pay

w/ multiple

fractured

sands

• Capstrings

installed mid-

perf after well

began to

liquid load.

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Capillary String Selection Process

CANDIDATE Condensate

<5 bbl/mmcf

WLR > 0.4 ?

Critical Rate

Check

N

Batch treat well

-Compare to SI of similar length at most 6mo

earlier, if none available then SI well without

batching (same SI time) for comparison

No cap string.

AFE/PM

Capillary

String

Batch Treat

Response


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Feb. 17 – 20, 2013 7

-Examine WB issues

(fill / fish / damage)

N

Poor

Y Y

Y

P

F

N

Production with Foam Injection

• Foam injection could be widely deployed in

different flow conditions and different points in

well life.

– Delaying move into compression

– Regain production after falling off trend

– Return slugging wells to constant flow

– Eliminate intermittent cycles

– Restore liquid loaded wells


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Feb. 17 – 20, 2013 8

Foam Example #1

Fell Off Production Trend

• Down to 200 mcfd prior to Foam

• Over 1000 mcfd w/ Foam


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Foam Example #2


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Intermittent

• 665 mcfd, 3 bcpd

• Increased to 1012 mcfd, 12 bcpd

Foam Example #3

Liquid Loaded

• 150 mcfd, 1

bcpd, 0 bwpd

average

• Increased to 350

mcfd, 10 bcpd,

10 bwpd

average after CS

installation


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Liquid Loaded

• 125 mcfd, 1

bcpd

• Increased to 350

mcfd, 10 bcpd

Cap String Success Through Time

2007-2010 Program

• 2007 – New

selection process

introduced

• 2008 – AFE process

streamlined

• 2010 – Candidate list

exhausted


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Feb. 17 – 20, 2013 12

South Texas Vicksburg Foam Injection Learnings

• Analytical Tools and Trials combined for best prediction of

success

– Turner/Coleman Critical Rate used as a key indicator

– Batch Treatments also used a key indicator

• Foam injection via capstring widely deployed

– Success with Water to Gas ratio as high as 350 bbl/mm

– Wells with Water to Condensate ratio as low as 50% can still

be successfully foamed.

• Mid Perf placement of capstring better than above top perf

placement

– Depends on fluid level in well

– Well integrity / casing collapse could prevent optimal

capstring placement


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Feb. 17 – 20, 2013 13

Analysis – Critical Rate

14

Turner – Critical

Rate equation

with adjustment

multiplier (red

line)

• Applied

additional

correction

factor to predict

psuedo critical

rate with foam

(blue line)


Denver, Colorado

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Analysis – Critical Rate

15

Critical Rate is the Best Indicator for Success


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Batch Treatment Screening

Uniform Process

• Compare batch treatment

with production following

a similar shut-in time.

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Batch Treatments in 2009 and Capstring Success

Batch Treatments good indicator for success but even a well

with a poor response can respond to continuous foam 2013 Gas Well Deliquification Workshop

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Response

> 100 mcfd Response

~ 50- 100 mcfd

Response

< 50 mcfd

Analysis – Capstring More Effective Mid-Perforation

2008-09 Experiment

• Mid perf placement shows better

response than other placements


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Feb. 17 – 20, 2013 18

Conclusions

• Well design and environment allowed for continuous

foam injection via capstrings at low upfront cost.

• Foam program in South Texas was very profitable but

increased chemical spending significantly as more wells

were lifted with foam.

• Foam injection via capstring could be deployed by “trial

and error” but some analysis and batch treatment tests

could be used to more accurately predict continuous

foam injection success.

• Some liquid loaded wells flowing at optimal production

rates and responding positively to a batch treatment

could still have poor production response to permanent

capillary string installation.


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• Reserves: Our use of the term “reserves” in this presentation means SEC proved oil and gas reserves.

• Resources: Our use of the term “resources” in this presentation includes quantities of oil and gas not yet classified as SEC proved oil and gas reserves. Resources

are consistent with the Society of Petroleum Engineers 2P and 2C definitions.

• Organic: Our use of the term Organic includes SEC proved oil and gas reserves excluding changes resulting from acquisitions, divestments and year-average pricing

impact.

•

• The companies in which Royal Dutch Shell plc directly and indirectly owns investments are separate entities. In this announcement "Shell", "Shell Group" and "Royal

Dutch Shell" are sometimes used for convenience where references are made to Royal Dutch Shell plc and its subsidiaries in general. Likewise, the words "we", "us"

and "our" are also used to refer to subsidiaries in general or to those who work for them. These expressions are also used where no useful purpose is served by

identifying the particular company or companies. "Subsidiaries", "Shell subsidiaries" and "Shell companies" as used in this announcement refer to companies in which

Shell either directly or indirectly has control, by having either a majority of the voting rights or the right to exercise a controlling influence. The companies in which Shell

has significant influence but not control are referred to as "associated companies" or "associates" and companies in which Shell has joint control are referred to as

"jointly controlled entities". In this announcement, associates and jointly controlled entities are also referred to as "equity-accounted investments". The term "Shell

interest" is used for convenience to indicate the direct and/or indirect (for example, through our 23 per cent shareholding in Woodside Petroleum Ltd.) ownership

interest held by Shell in a venture, partnership or company, after exclusion of all third-party interest.

• This announcement contains forward looking statements concerning the financial condition, results of operations and businesses of Shell and the Shell Group. All

statements other than statements of historical fact are, or may be deemed to be, forward-looking statements. Forward-looking statements are statements of future

expectations that are based on management's current expectations and assumptions and involve known and unknown risks and uncertainties that could cause actual

results, performance or events to differ materially from those expressed or implied in these statements. Forward-looking statements include, among other things,

statements concerning the potential exposure of Shell and the Shell Group to market risks and statements expressing management’s expectations, beliefs, estimates,

forecasts, projections and assumptions. These forward looking statements are identified by their use of terms and phrases such as "anticipate", "believe", "could",

"estimate", "expect", "goals", "intend", "may", "objectives", "outlook", "plan", "probably", "project", "risks", "seek", "should", "target", "will" and similar terms and phrases.

There are a number of factors that could affect the future operations of Shell and the Shell Group and could cause those results to differ materially from those

expressed in the forward looking statements included in this announcement, including (without limitation): (a) price fluctuations in crude oil and natural gas; (b) changes

in demand for Shell's products; (c) currency fluctuations; (d) drilling and production results; (e) reserves estimates; (f) loss of market share and industry competition; (g)

environmental and physical risks; (h) risks associated with the identification of suitable potential acquisition properties and targets, and successful negotiation and

completion of such transactions; (i) the risk of doing business in developing countries and countries subject to international sanctions; (j) legislative, fiscal and

regulatory developments including regulatory measures addressing climate change; (k) economic and financial market conditions in various countries and regions; (l)

political risks, including the risks of expropriation and renegotiation of the terms of contracts with governmental entities, delays or advancements in the approval of

projects and delays in the reimbursement for shared costs; and (m) changes in trading conditions. All forward looking statements contained in this announcement are

expressly qualified in their entirety by the cautionary statements contained or referred to in this section. Readers should not place undue reliance on forward looking

statements. Additional factors that may affect future results are contained in Shell's 20-F for the year ended 31 December 2011 (available at www.shell.com/investor

and www.sec.gov ). These factors also should be considered by the reader. Each forward looking statement speaks only as of the date of this announcement, 5

February 2013. Neither Shell nor any of its subsidiaries nor the Shell Group undertake any obligation to publicly update or revise any forward looking statement as a

result of new information, future events or other information. In light of these risks, results could differ materially from those stated, implied or inferred from the forward

looking statements contained in this announcement.

• Shell may have used certain terms, such as resources, in this announcement that the SEC strictly prohibits Shell from including in its filings with the SEC. U.S.

investors are urged to consider closely the disclosure in Shell's Form 20-F, File No 1-32575, available on the SEC website www.sec.gov. You can also obtain these

forms from the SEC by calling 1-800-SEC-0330.

DEFINITIONS AND CAUTIONARY NOTE

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Disclaimer

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foam injection via capillary string in vicksburg dry …...gas well deliquification workshop...

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