STATE OF ALASKA
OIL AND GAS CONSERVATION COMMISSION
3001 Porcupine Drive
Anchorage, Alaska 99501-3192
IT APPEARING THAT:
|Re: The APPLICATION OF
("GRI") for approval to pump formation)
waters derived from coal seams into a)
deeper sandstone interval
||Disposal Injection Order
Houston Gas Field
Houston Gas Well No. 3
||June 30, 1998
By correspondence dated May 15, 1998, GRI requested authorization from
the Alaska Oil and Gas Conservation Commission to pump formation waters
produced from the dewatering of coal seams into a deeper sandstone interval
with higher salinity formation water without first producing the water
to the surface. The production perforations and underlying receiving zone
perforations are within the same well.
GRI filed the application on an area basis for the Houston Gas Field; however,
information supplied within the application is specific only to the Houston
No. 3 well.
The Commission requested additional information June 11, 1998. GRI provided
the requested information on June 12 and 19, 1998.
The Commission published notice of opportunity for public hearing in the
Anchorage Daily News on May 27, 1998 and in the Frontiersman on May 27,
The Commission did not receive any protest or request for a public hearing.
GRI is the operator of the Houston Gas Field. There are no other operators
within a one-quarter mile radius of the Houston No. 3 well.
Surface owners within a one-quarter mile radius of Houston No. 3 have been
duly notified of the proposed operation.
The Rosetta No. 3 well is within one-quarter mile of Houston No. 3. Rosetta
No. 3 has been plugged and abandoned in accordance with 20 AAC 25.105.
Logs from Houston No. 3 may be used to define the disposal and confining
zones proposed for subsurface disposal of fluids in the Houston Gas Field.
The proposed disposal zone is an unnamed sand in the basal portion of the
Tyonek Fm. between the measured depths of 1886 feet and 2030 feet in the
Houston No. 3. The lithology consists of fine- to coarse-grained arkosic
sandstone grading toward the base to lithic quartz-pebble conglomerate.
The production interval is between the measured depths of 1338 feet and
1856 feet in the Houston No. 3.
The proposed confining zone consists of Tyonek Fm. claystones between the
measured depths of 1856 feet and 1867 feet in Houston No. 3.
Industry standard interpretation of cement bond logs obtained by GRI indicates
Houston No. 3 is adequately cemented to provide isolation between the intended
disposal zone and the base of freshwater aquifers in the area.
Houston No. 3 surface casing consists of 505 feet of 7 inch, 23 lb. per
foot casing cemented in place. The production casing consists of 2030 feet
of 4.5 inch, 10.75 lb. per foot casing cemented to surface. The well is
not equipped with tubing.
GRI collected water samples during the drilling of the Houston 1, 2 and
3 wells. These water samples and samples taken from adjacent oil and gas
wells and coal exploration holes indicate the base of freshwater with salinity
greater than 10,000 parts per million is about 800 feet below ground level
in this vicinity.
The formation water salinity gradient in the Houston Gas Field increases
Water derived from coalbed methane gas production will be gravity separated
in the well and the water will be pumped into the basal receiving zone
using a subsurface pump.
The subsurface pump will be positioned in a packer that will confine injection
pressure to the proposed receiving interval.
Total water volume to be pumped is estimated at 200,000 barrels. The rate
of water production from the coal seams is expected to decline with time.
The average rate of the subsurface pump will be about 1130 barrels of water
per day and maximum anticipated is 1400 barrels per day. Average bottom
hole pressure is expected to be 1250 psi; maximum pump pressure will be
Accepted fracture theory for sandstone buried at shallow depth, similar
depth to the interval for disposal operations in Houston No. 3, require
pump rates significantly higher than those anticipated with the intended
pumping equipment to propagate fractures in the receiving zone. Shallow
depth fracture orientation is normally horizontal.
Integrity of the system will be monitored based on production rates of
gas and water, wellhead pressure and pump operation parameters. Operating
wellhead pressure is not expected to exceed 100 psi and shut-in pressure
due to a gas column may be as high as 800 psi.
NOW, THEREFORE, IT IS ORDERED THAT:
There are freshwater aquifers to a depth of 800 feet underlying the Houston
Fluids authorized for disposal under this order in the Houston Gas Field
will consist of coal seam formation waters generated from coalbed methane
Permeable strata that reasonably can be expected to contain the total volume
of disposal fluids anticipated for this project are present in a basal
sandstone of the Tyonek Formation in the Houston Gas Field.
Disposal pressure and fluids will be isolated within the wellbore to the
interval below the pump packer.
Confining lithology, cement isolation of the wellbore and operating conditions,
will confine movement of disposal fluids within appropriate receiving intervals.
Pumping operations are not expected to induce fractures in the receiving
formation at the low rate and rated pump pressure.
Mechanical system integrity and surveillance data will be monitored continually
using gas rate performance, indications of water production at surface
with the gas, wellhead pressure and pump performance.
Disposal operations will not inject fluids into, through or above a freshwater
The underground disposal of produced water, without first producing the
water to the surface, is an environmentally preferred alternative that
reduces the risk of movement of fluids into sources of freshwater.
Waiver of the tubing and pressure test requirements of 20 AAC 25.412 will
not result in an increased risk of movement of fluids into a freshwater
The proposed operation conforms to all other regulatory requirements for
subsurface disposal of produced formation waters.
The proposed disposal injection operations in the Houston Gas Field will
not cause waste, jeopardize correlative rights, impair ultimate recovery,
or affect overlying freshwater aquifers.
Rule 1 Authorized Injection Strata for Disposal.
Waters derived as a by product of coalbed methane production in the
Houston No. 3 well may be injected without first being brought to the surface,
in conformance with this order, into a basal Tyonek Formation sandstone
unit which occurs between the measured depths of 1886 and 2030 feet in
Houston No. 3. This project may be further conditioned by administrative
action after review of injection performance.
Rule 2 Demonstration of System Integrity
System integrity will be demonstrated by continual monitoring of gas
rate and water rate at surface, wellhead pressure and pump performance
Rule 3 Well Integrity Failure
Whenever water rates produced at surface, operating pressure observations
or pump operations indicate pressure communication or leakage of any casing
or packer, the operator must immediately cease injection and notify the
Commission no later than the first working day following the observation,
obtain Commission approval of a plan for corrective action and obtain Commission
approval to continue disposal.
Rule 4 Surveillance
Surveillance will consist of gas rate observations, water rate or volume
produced at surface, wellhead pressure observation and pump performance
Rule 5 Administrative Action
Upon request, the Commission may administratively revise and reissue
this order upon proper showing that any changes are based on sound engineering
practices and will not allow waste fluids to escape from the disposal zone.
DONE at Anchorage, Alaska and dated June 30, 1998
David W. Johnston, Chairman
Robert N. Christenson, P.E. Commissioner
Camillé Oechsli, Commissioner
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