injection well field optimization using analytical … methods › ms. sheila duchek, m.sc., p.geo....

›Injection Well Field Optimization Using Analytical Methods

›Ms. Sheila Duchek, M.Sc., P.Geo. April 5, 2018 for

EnviroTech 2018

A world leader

Founded in 1911, SNC-Lavalin is one of the leading engineering and construction

groups in the world and a major player in the ownership of infrastructure. From

offices in over 50 countries, SNC-Lavalin's employees are proud to build what

matters. Our teams provide EPC and EPCM services to clients in a variety of industry

sectors, including oil and gas, mining and metallurgy, infrastructure and power.

SNC-Lavalin can also combine these services with its financing and operations

and maintenance capabilities to provide complete end-to-end project solutions.

2

Presentation Outline

3

› Disposal Wells – What are they? What do they look like and what are they

used for?

› Why would the public be concerned about these wells?

› Regulatory Environment

› An approach to planning and designing disposal wells for industry:

› Regional Assessments, Permitting and Regulations,

Fluid Compatibility Assessments

› Testing Requirements and Interpretation

› Cumulative Effects Assessment

› Why spend resources on assessment work for disposal wells?

What is an injection well vs disposal well?

4

›According to the U.S. Environmental Protection Agency. 2015. General Information about Injection Wells. Washington, DCthe definition of an injection well is:

›A device that places fluid deep underground into porous rock formations, such as sandstone or limestone, or into or below the shallow soil layer. The fluid may be water, wastewater, brine (salt water), or water mixed with chemicals.

›A disposal well refers to the deep well injection of waste fluids into an appropriate geologic formation that will safely contain and isolate the waste fluids.

Injection Wells: A Variety of Uses

5

›Injection wells have many uses, including disposal and / or storage of fluids and to manage pressures within targeted formations.

Specific applications include:› Oil and gas production, including waterflood & SAGD operations› Wastewater, process water disposal for industrial operations› Aquifer recharge for drought management › Geothermal energy cycling › Saltwater intrusion prevention› CO2 storage› Mining support

Disposal Wells: What are they?

6

Disposal Wells: What are they?

7

Source: J. Veil Source: J. Doubek

Applicable Regulations

8

AER Directive 051: Injection and Disposal Well Classifications, Completions, Logging, and Testing Requirements

AER Directive 058: Oilfield Waste Management Requirements for the Upstream Petroleum Industry

›Province of Alberta:

›Oil and Gas Conservation Act, Rules and Regulations

Deepwell Disposal Philosophy (AER Directive 51)

9

Disposal of oilfield and industrial waste waters in Alberta is a safe and viable disposal option where wells are properly constructed,

operated, and monitored.

› Waste minimization should be prioritized

› Resource conservation should be pursued whenever possible

› Disposal wells should be managed and monitored, based on fluids

› Wastes will not be diluted to avoid waste fluid classification

› Operators will design and operate facilities using sound practices

Deepwell Disposal in Alberta: Prohibited List

10

›The following are prohibited from disposal by subsurface injection, except under exceptional circumstances:

› Municipal or industrial sewage

› Surface run-off water that meets surface discharge criteria,

or can meet surface discharge criteria without

cost-prohibitive treatment

› Lube oils and spent solvents

› Diesel invert drilling fluids

› Wastes where appropriate treatment technology exists

(economically and technically)

Why do Disposal Wells cause Public Concern?

11

In the news, disposed fluids can been deemed potentially harmful wastes with high salts, chemicals, heavy metals, or radioactive material.

Well construction depends on the fluid injected and the depth of the injection zone.

›It is common to use repurposed wells.

›Well efficiency can be a huge challenge in repurposed wells.

An Approach to Planning for Disposal Wells

12

›Repurposed wells may be a cost-effective option, because of reusing an existing cased hole but... retro-fitting can be expensive.

›Reactive management can be expensive.

›It can be a big issue to operations if a disposal well malfunctions.

›“Forewarned, forearmed; to be prepared is half the victory” (Miguel de Cervantes)

›A hydrogeological assessment can quantify uncertainty.

Hydrogeologists, Petroleum & Geological Engineers

13

All these specialists also have or should have the same or similar tool kit:

The approach to planning and designing disposal wells

should include:

› Regional Assessments

› Permitting and Regulations Approvals

› Fluid Compatibility Assessments

› Testing Requirements and Interpretation

› Cumulative Effects Assessment

Hydrogeologists can assess for issues with near surface groundwater and surface water resources.

Understanding the Regional Geology

14

We are first and foremost: Geologists

Start with regional geology assessments

Our assessment ensures we understand:

› Physical parameters of candidate aquifers

› Properties and characteristics of aquitards

› Chemical parameters of formation fluids

The biggest uncertainty is hydraulic

conductivity.

Water levels (pressures) are required data.

Understanding Disposal Needs

15

As part of planning, information regarding the nature of the waste fluid is compiled:

› What is the chemistry?

› How much waste fluid will be generated?

› What are the waste fluid generation rates?

› When? Will there be peak disposal times?

› Where is the fluid coming from?

› How will it be transported?

› Will there be filtration needs?

Using Models

16

›We organize our data into models.

›Our site-scale models can be built using a combination of analytical and semi-analytical techniques.

›Our model frameworks are selected in consideration of:

› Accuracy

› Flexibility

›This allows well field layout options to be assessed and altered relatively quickly.

›

Using Models

17

Allowing assessment of different parameters to determine sensitivity and identify uncertainty to guide planning, such as:

› Injection rates

› Sequencing

› Well spacing

› Number of wells

From this, we can determine data gaps we need to address with field data.

Fluid Compatibility Testing

18

›An assessment conducted on waste fluids to ensure injected fluids do not have any undesirable reactions within the disposal well,

associated equipment or within the disposal reservoir.

Certain fluids may cause significant and potentially damaging reactions. Damage occurring from fluid incompatibility may include:

› Fines migration › Clay swelling › Scale formation › Organic deposition › Mixed organic and inorganic deposition


19

›Fines Migration:

Particles


20

›Fines Migration:


21

›Fines Migration:


22

›Fines Migration:


23

›Fines Migration:

›Clay Swelling:

Clay particles


24

›Fines Migration:

›Clay Swelling:


25

›Fines Migration:

›Clay Swelling:


26

›Fines Migration:

›Clay Swelling:


27

›Scale Formation:

Particles


28

›Scale Formation:


29

›Scale Formation:

›Organic Deposition:


30

›Scale Formation:



31

›Scale Formation:



32

›Scale Formation:


Injection Well Classifications and Requirements During Drilling and Completion

33

›Classifications According to Directive 51

•Oilfield / Industrial Wastes Class 1a

•Produced Water / Specified Wastes Class 1b

•Produced Water / Brine Equivalent Class II

•Hydrocarbon / Inert / Sour Gases Class III

•Steam / Potable Water Class IV

All classes have cementing and casing requirements, including:

hydraulic isolation of host zone and cement across useable groundwater.

All classes have initial logging requirements, including cement top

locator; hydraulic isolation and casing inspections.

Injection Well Testing Requirements

34

Formation Fracture Pressure

(Pressure above which injection of fluids will cause fracturing).

VS

Maximum Wellhead Injection Pressure (MWHIP).

(Pressure observed during the test performed in advance of submitting the application for regulatory approval).

The Formation Fracture Pressure is determined by a step-rate injectivity test, an in-situ stress test or mini frac.

The Injection Step Test: Changes in Pressure over Time with Increasing Injection Rates

35Time

Pre

ssure

Scenario 1: Improvement over time?

36Time

Pre

ssure

Injection Well

Seems to be

Accepting

More

Increasing

Injection

Rates with

Time

37

Well A Well B

DISPOSAL FORMATION

INITIAL DISPOSAL FORMATION PRESSURE

Cumulative Effects

38

Well A Well B

DISPOSAL FORMATIONINJECTED

FLUIDS


Cumulative Effects

39

Well A Well B

DISPOSAL FORMATIONINJECTED

FLUIDSINJECTED

FLUIDS


COMPOSITE DISPOSAL

PRESSURE INCREASE

DUE TO INJECTION AT

WELLS A & B

40

Cumulative Effects Assessment

Why Spend Resources on Injection Wells?

41

›Why spend to have a fit-for-purpose disposal well vs repurposed?

›Cost savings in operational costs because:

› The well operates with more reliability

› The well requires less maintenance

› The well requires less power to operate

›These improvements are all due to better well efficiency.

›Reduced liability for energy producers

› The well design ensures fluid moves through screens not elsewhere

› Inefficiency causes stress on well materials which can lead to failure

Summary

42

›Disposal wells are an essential part of operations for the energy-production industry.

›Often, disposal wells are retro-fitted existing cased holes. Planning is based on anecdotal data from surrounding disposal wells.

›A failure or malfunction in a disposal well can be extremely costly.

›A hydrogeologist can assess the target aquifers, well construction well performance and quantify uncertainty.

›Hydrogeologists also add value in terms of the assessment and planning around near surface groundwater and surface water resources.

Our values keep us anchored and on track. They speak to how we run our business, how we express

ourselves as a group, and how we engage with our stakeholders and inspire their trust.

Values that guide us

Teamwork & excellenceWe’re innovative, collaborative, competent

and visionary.

Customer focusOur business exists to serve and add long-term

value to our customers’ organizations.

Strong investor returnWe seek to reward our investors’ trust

by delivering competitive returns.

Health & safety, security and environmentWe have a responsibility to protect everyone who

comes into contact with our organization.

Ethics & complianceWe’re committed to making ethical decisions.

RespectWe consistently demonstrate respect for all

our stakeholders.

43

injection well field optimization using analytical … methods › ms. sheila duchek, m.sc., p.geo....

Documents