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OIL INDIA LIMITED Well abandonment policy

INTRODUCTION

Hydrocarbon exploration activities started in Upper Assam Basin way back in 1880.

Since then more than 2500 wells of varying depths were drilled by erstwhile AOC

and its progeny Oil India Limited, for primary purpose of hydrocarbon exploitation.

Many of these wells have become unproductive due to many a reasons or kept

closed for extraction of possible hydrocarbon, predominantly gas, on a later date,

subsequent to drainage of economically viable liquid hydrocarbon.

Though a few of such shut in wells can be recompleted for production of gas, oil or

as water injector or as a water disposal well, the same shall remain as an unused

inventory in company’s records. Moreover, due to miscreant activities such as

tampering and pilferage of these well, the situations sometime may lead to

uncontrollable release of oil and gas to atmosphere and subsequent fire incidents.

Therefore, certain laid down policy guide lines are required to shut the unproductive

wells.

Moreover, Proper well abandonment shall also prevent pressure build up or cross

flow in the well and its surroundings by isolating all permeable hydrocarbon zones

and water zones of different pressure regimes from each other .

In view of the above, it has become more of an urgent necessity to frame up a policy

/ guideline to be followed across our company for well abandonment jobs in onshore

E&P activities.

1.0 EXISTING PRACTICES FOLLOWED BY OIL

Presently five different nomenclatures are in vogue in the company to describe the

status of a well. They are

a) Producing well: These are the wells producing Oil / Natural gas.

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b) Shut in well: Well not on production and kept shut in for want of flow lines or

damaged well head by miscreants or other integrity issues. Also, wells with no

production and with no further prospects awaiting abandonment.

c) Temporarily abandoned well: The well has been abandoned temporarily.

However there is possibility of converting the well to other utility wells.

d) Permanently abandoned well: The wells with no further prospects and have been

identified for permanent abandonment.

e) Sick Wells: The wells which are not able to sustain self flow and require workover

for completion with artificial lift.

1.1 The decision for keeping a well shut or temporarily abandon is taken in Field

Head Quarter (FHQ) level, while approval for permanent abandonment is granted by

corporate office.

1.2 Permanent well abandonment is carried out by placing plugs mainly cement,

with mud plugs in between. The practice concurs to the OMR specifications of well

abandonment vide section 59 (a) to (e). Temporary abandonment is done by placing

cement plugs at the bottom or by placing bridge plug or both. However, the well head

is susceptible to pilferage and snubbing in of foreign materials in the tubing making

future intervention jobs difficult.

1.3 Considerations for framing up of policy.

a. For ease of understanding and clarity, it is suggested that the wells should be

classified mainly in to three categories only. They are producing well, shut in well

and abandoned well. The essential factor in consideration to determine or

differentiate between shut in well or abandoned well is time and potential of the well.

b. Wells are Abandoned (permanently) immediately after drilling due to either

poor hydrocarbon prospects or operational problems (Downhole). Producing wells

are to be abandoned at the end of useful economic life. Wells with further remaining

prospects are generally not abandoned.

c. While framing the policy it is very much essential to use experience, expertise

and judgement including the fulfilment of various clauses of OISD-STD-175 & also

OMR 1984 / other guidelines.

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2.0 OBJECTIVE :

Total number of wells drilled by the company in Assam & AP upto October ,2015 is

1465 excluding Digboi field Break-up of the status of these wells is as under

Oil Producing : 308

Gas Producing : 85

Water Injection : 44

Water Disposal : 187

Under Testing : 56

Awaiting Testing : 56

Under Work over : 16

Sick : 387

Shut in : 29

Temporarily abandoned : 174

Abandoned : 99

2.1 As shown above a large number of wells are inactive due to various reasons

and some of which are idle for a long period of time. Such wells which don’t have

any economic useful life any more are yet to be abandoned. On the other hand,

some of the wells though declared abandoned but do not conform to the

abandonment criteria mentioned in the statutory Regulations, OISD guidelines and

international best practices etc. Such wells, if not abandoned properly may lead to

various safety and environmental issues. Hence, the need of the hour is to have a

well defined effective and practical well abandonment policy in place, which will be

uniformly followed across our company. Resident Chief Executive vide his letter no

RCE:23-09 dated January 19,2016 formed a committee comprising the following

members to frame a Well Abandonment Policy for the Company.

a. Shri A.K.Acharya GM ( HSE) - Chairman

b. Shri A.M.Mamen GMP( Optimization)- Team Leader

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c. Shri Neelimoy Barua Head ( G&R) - Member

d. Dr B.N.Sahoo CE ( S&E) - Member

e. Shri A.Biswas CE ( Drilling) - Member

f. Sanjay Verma CEP (Oil) - Member

g. D.K.Bordoloi CE ( Civil) - Member

The Term Of Reference (TOR) of the committee are as follows.

Criteria for selection of wells for abandonment

Procedure for abandonment of wells considering present practice and

statutory requirements

Site Restoration / Reclamation.

3.0 CRITERIA FOR SELECTION OF WELLS ABANDONMENT :

Criteria for selection of wells for abandonment can be put under two

Categories

3.1 Criteria for abandoning drilling wells

a) When the well is found to be without any indication of presence of

hydrocarbon.

b) When indication of hydrocarbon was found but subsequent production testing

results failed to establish presence of hydrocarbon / commercial hydrocarbon

and no other utility of the well viz. conversion to water injector/disposal or any

such purpose, could be envisaged/operationally feasible.

3.2 Criteria for selection of old / completed wells (in Producing, Shut-in or

Temporarily abandoned category ) for abandonment:

a) When all hydrocarbon prospects encountered in the well has been deemed to

have been exploited and no other utility of the well viz. conversion to water

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injector/disposal or any such purpose, could be envisaged/operationally

feasible.

b) Uncontrolled / controllable flow of oil and gas leading to well integrity failure /

environmental hazards.

c) Indications of impending / irreparable well integrity failure, due to which

production and/or any other operation cannot be continued on environmental /

safety considerations.

d) When production and/or any other operation cannot be continued due to

environmental reasons / natural calamities viz. river erosion, sinking of well

head / cellar areas etc.

In addition to the above, a well may require to be closed for a prolonged period due

to various reservoir / operation related reasons. In such a case, the well has to be

temporarily abandoned following laid down OMR / OISD guidelines. The criteria for

temporary abandonment may be due to any but not exhaustive of the following

reasons:

3.3 Criteria for selection of wells for Temporary Abandonment

3.3.1 Wells where workover operation is not possible due to complicated nature of

down-hole operations, for which required technology is not currently available

with OIL, but has been planned to be inducted in future, once sufficient

number of similar wells are in the inventory to make the investment

economically attractive.

3.3.2 Wells having multiple hydrocarbon bearing zones, where all oil bearing zones

have been exploited and remaining zones are having only gas cap of

reservoirs from which oil is being drained by other wells.

3.3.3 Wells in far-flung areas where hydrocarbon has been discovered but

evacuation facility is envisaged to take prolonged time. (viz. Well Rangmala-1)

3.3.4 a. Wells where all prospects have been exploited, but envisaged to

be having future purposes viz. water injection / disposal etc.

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b. When indication of hydrocarbon was found but subsequent

production testing results failed to establish regular production of

hydrocarbon, but it was envisaged to use the well for other purposes

viz. window-cutting/side-tracking to drill a different hole, water injection

/ disposal etc. in the future.

4.0 WELL ABANDONMENT

4.1 CLOSURE OF PRODUCING WELLS

4.1.1 When it is intended to temporarily close any producing well for a period

exceeding 30 days, it shall be filled with mud or water or oil so that the hydrostatic

pressure of the fluid column over-balances the formation pressure to prevent

leakage of hydrocarbon from the wellhead unless it is required for operational

purposes (e.g. pressure monitoring, etc.).

4.1.2 The control valves of the Christmas tree shall be completely closed and

control wheels shall be removed.

4.1.3 The Christmas tree shall be physically examined for any other abnormality or

leakage once in 30 days by a competent person authorized for the purpose. In case

any leakage is detected during such examination the competent person shall take

immediate steps to stop it.

4.1.4 A report of every such examination shall be recorded in a bound paged book

kept for the purpose and shall be signed and dated by person making the

examination.

4.2 PERMANENT ABANDONMENT

4.2.1 Open Hole Abandonment

4.2.1.1 In uncased portion of well, cement plug shall be set to extend from a

minimum of 30 m below the bottom to 30 m above the top of any oil, gas,

or reservoir zones.

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4.2.1.2 The plug in the open hole shall be tagged after Wait on Cement (WOC) by

applying weight of at least 8 MT on the plug and pressure tested at 1,000

psi or up to Leak Off Test (LOT) value at shoe whichever is less.

4.2.1.3 In case there is no oil, gas, or reservoir zone, the open hole shall be

isolated by placing cement plug of minimum 30 m below and 30 m inside

deepest casing shoe.

4.2.1.4 For expected or known lost circulation conditions, a mechanical barrier

device like bridge plug/retainer should be set at least 15 m above the

casing shoe with minimum of 15 m of cement on top of the device.

Alternatively lightweight slurry designed for adequate compressive

strength may be used.

4.2.2 Cased Hole Abandonment

4.2.2.1 Cement plug shall be set at least 30 m above to 30 m below the perforated

interval, or down to a casing plug, whichever is less. When abandoning

multiple permeable zones, due consideration shall be given to the number

of permeable zones and whether isolation of all the zones is required or

not. If multiple zones are not required to be isolated from one another,

isolation of all zones from the rest of the well can be achieved by

squeezing & plugging the shallowest zone.

4.2.2.2 When there is completion packer(s) in the hole and we are not able to

retrieve it, the perforated intervals below the packers should be isolated by

squeezing cement through the packer or spotting cement across the

perforations. Cement should then be spotted above the packer.

4.2.2.3 The liner laps, if any, shall be isolated by setting a cement plug/ bridge

plug across the top of the liner, which shall extend at least 30m into the

liner. This can be omitted for the liner lap only if the liner lap was

confirmed to have good cement by CBL/CET/USIT and has been

successfully pressure/inflow tested earlier.

4.2.2.4 If casing(s) are cut and retrieved thereby leaving a stub inside the next

larger string, abandonment cement plug(s) shall be set so as to extend a

minimum of 30 m inside deepest stub and 30 m above largest stub

covering all the annuli.

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4.2.2.5 While placing abandon plug in open hole or cased hole stated above it

shall be ensured that the wellbore including the space between the cement

plugs is filled with drilling fluid of sufficient specific gravity and other

properties so as to enable it to withstand any subsequent pressure which

may develop in the wellbore.

4.2.3 Surface Abandonment Plug

4.2.3.1 Before placing surface plug, all annuli shall be checked for any activity by

opening wellhead valve.

4.2.3.2 Surface cement plug of at least 60 m length shall be placed in such a

manner that the top of the plug is within 60 m below the mean ground level

in the smallest string of casing.

4.2.3.3 Capping and marking of the abandoned well shall be done to the

satisfaction of local regulatory bodies.

4.3 TEMPORARY ABANDONMENT

4.3.1 A bridge plug or a cement plug of at least 60 m in length shall be set at the

base of the deepest casing string, unless the casing has been cemented and has not

been drilled out. If a cement plug is set, it is not necessary for the cement plug to

extend below the casing shoe into open hole and

One of the following types of plugs shall be set in the casing with the top of the plug

no more than 300 m below the mud line:

a) Retrievable bridge plug / packer

b) Permanent type bridge plug

c) Cement plug at least 60 m in length

4.4 The procedure for plug cementation & verification should be as follows:

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4.4.1 PLUG CEMENTATION

4.4.1.1 A cementing plan shall be issued for each cement plug job.

4.4.1.2 The properties of the set cement plug shall be capable to provide lasting

zonal isolation.

4.4.1.3 Cement slurries used in plugs to isolate permeable and abnormally

pressured hydrocarbon bearing zones shall be designed to prevent gas

migration.

4.4.1.4 Permanent cement plugs shall be designed to provide a lasting seal with

the expected static and dynamic conditions and loads downhole.

4.4.1.5 The cement plug shall be designed for the highest differential pressure

and highest downhole temperature expected, inclusive of installation and

test loads.

4.4.1.6 Minimum batch volume of cement shall be defined for the plug to ensure

that that homogenous slurry can be made, taking into account the

contamination on surface and downhole.

4.4.1.7 The firm plug length shall be minimum 60 m. If a plug is set inside casing

and with a mechanical plug as a foundation, the minimum length shall be

15 m.

4.4.1.8 The plug shall extend minimum 30 m (measured depth) above any source

of inflow/ leakage point. A plug in transition from open hole to casing

should extend at least 30 m (measured depth) below casing shoe.

4.4.2 PLUG VERIFICATION :

4.4.2.1 The strength development of the cement slurry shall be verified through

observation of representative surface samples from the mixing cured

under representative temperature and pressure conditions.

4.4.2.2 The plug installation shall be verified through documentation of job

performance; records from cement operation (volumes pumped, returns

obtained during cementing, etc.).

4.4.2.3 Position and strength of the plug shall be verified by:

Open hole: Tagging to confirm depth of firm plug.

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Cased hole: Tagging to confirm depth of firm plug and a pressure test, which

shall be 1000 psi above estimated formation strength at a point below casing/

potential leak path. For surface casing plugs, test pressure will be 500 psi.

However the test pressure shall not exceed casing test pressure, less

casing wear factor. Cased hole plugs should be tested either in the

direction of flow or from above.

4.4.2.4 If a mechanical plug is used as a foundation for the cement plug and is

tagged and pressure tested, the cement plug need not be verified.

4.4.2.5 For temporarily abandoned wells, the fluid level/ pressure above the

shallowest set plug shall be monitored regularly when access to the bore

exists.

4.4.2.6 For radioactive source material left in the well which could not be removed,

a cement plug of minimum length 50 m and at least specific gravity 2.35

shall be placed over the location where the source is stuck. Guidelines of

Atomic Energy Regulatory Board, Govt. of India shall be followed in this

regard.

5.0 SITE RESTORATION / RECLAMATION

5.1 Site Restoration: After comopletion of drilling activity & production testing,

if the well is on production, the well plinth needs to be restored as per

following procedure-

Dressing & levelling the well plinth.

Dump pit of adequate size to be made for proper dumping of all

garbage / debris generated at site.

Dumping all surface debris / wastes / jutes / rejected ropes etc., into

the dump pit and covering with earth.

Dismantling various cement concrete & brick masonry works of

temporary nature.

Drill cuttings/ Oil spill scrapings to be disposed in designated HDPE

lined pits, covered with HDPE sheet and filled up with top soil.

Necessary protection to ensure any form of leakage from toilets.

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Necessary repair/ strengthening of bundh of effluent pits to avoid

overflow of effluents. The effluent pits are to be completely filled up

with earth in case of the wells which are permanently abandoned.

Providing fencing around the well plinth.

Tree plantation in the periphery of the location.

Completion status of restoration is to be assessed & documented.

5.2 In case of abandonment of the well, the well plinth needs to be fully reclaimed

to its original position:

The cellar or pit around the well shall be filled up and the land shall be

restored to the original level by filling up the pits with top soil, dressing

and levelling ground and disposing off all the debris etc.

Every abandoned well shall be clearly identified at site and on the plan.

5.3 Regarding disposal or utilization following options may be adopted:

5.3.1 The land may be retained by OIL for future operational use. In such case,

necessary demarcation with permanent posts/ enclosure should be made to

secure the land and prevent it from encroachment.

5.3.2 If future use of the land is not envisaged, it is necessary to revert it to the pre

acquisition state. i.e tea garden land should be converted back to tea

plantation, agriculture land should be converted back to agriculture land etc.

Regarding the right to cultivation/plantation of this land attempt may be made

to allocate the land as per the law of the land. There are certain guidelines/

directives available in this regard. A separate committee may be constituted to

look into the subject.

5.3.3 Abandoned wells in Forest Area: After proper abandonment of the wells as

per OIL’s policy & guidelines, the same shall be handed over to forest

department of Government of Assam.

5.3.4 The details of the abandoned wells shall be prepared circulated to the

Installation Manager concerned with a copy to concerned departments as per

prescribed format/well tag in Annexure-1.