U.S. patent application number 13/621815 was filed with the patent office on 2013-03-28 for method and system for providing temporary formation sealant.
This patent application is currently assigned to AltaRock Energy, Inc.. The applicant listed for this patent is AltaRock Energy, Inc.. Invention is credited to Daniel Bour, Susan Petty.
Application Number | 20130075089 13/621815 |
Document ID | / |
Family ID | 47883832 |
Filed Date | 2013-03-28 |
United States Patent
Application |
20130075089 |
Kind Code |
A1 |
Bour; Daniel ; et
al. |
March 28, 2013 |
METHOD AND SYSTEM FOR PROVIDING TEMPORARY FORMATION SEALANT
Abstract
A method and system for providing a temporary sealant within a
wellbore of a subterranean formation is disclosed. According to one
embodiment, the temporary sealant comprises a particulate material
and a liquid. The particulate material and the liquid are mixed to
a predetermined dilution ratio. The temporary sealant is pumped
into fractures via an open hole of the wellbore. The particulate
material accumulates and is left within the fractures to set. Over
a predetermined period of time, the particulate material degrades,
disintegrates, or dissolves within the fractures.
Inventors: |
Bour; Daniel; (Granite
Falls, WA) ; Petty; Susan; (Shoreline, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AltaRock Energy, Inc.; |
Seattle |
WA |
US |
|
|
Assignee: |
AltaRock Energy, Inc.
Seattle
WA
|
Family ID: |
47883832 |
Appl. No.: |
13/621815 |
Filed: |
September 17, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61535820 |
Sep 16, 2011 |
|
|
|
Current U.S.
Class: |
166/250.01 ;
166/281; 166/285 |
Current CPC
Class: |
E21B 43/261 20130101;
C09K 8/516 20130101; E21B 33/138 20130101 |
Class at
Publication: |
166/250.01 ;
166/285; 166/281 |
International
Class: |
E21B 33/138 20060101
E21B033/138; E21B 43/26 20060101 E21B043/26 |
Claims
1. A method comprising: preparing a temporary sealant comprising a
particulate material and a liquid according, the particulate
material and the liquid being mixed to a predetermined dilution
ratio; pumping the temporary sealant into fractures via an open
hole of a wellbore in a subterranean formation; allowing the
particulate material to accumulate and set within the fractures;
and allowing the temporary sealant to degrade, disintegrate, or
dissolve within the fractures over a predetermined period of
time.
2. The method of claim 1 further comprising drilling the open hole
after the particulate material is set within the fractures.
3. The method of claim 2, wherein the open hole is drilled to a
total depth (TD).
4. The method of claim 2, wherein the predetermined dilution, ratio
is determined according to a drilling schedule.
5. The method of claim 1, the predetermined dilution ratio is
determined according to a pumping capacity of a pump used to pump
the temporary sealant.
6. The method of claim 1, the predetermined dilution ratio is
determined according to a size, a number, a volume, and/or porosity
of the fractures.
7. The method of claim 1 further comprising circulating the liquid
of the temporary sealant out of the wellbore.
8. The method of claim 1, wherein the period is affected by a
temperature, a pressure, and/or a chemical condition of the
fractures.
9. The method of claim 1, wherein the temporary sealant is used for
oil and gas well (O&G) hydraulic fracturing.
10. The method of claim 1, wherein the temporary sealant is used
for hychoshearing stimulation in an enhanced geothermal system
(EGS).
11. The method of claim 10, wherein the temporary sealant is pumped
at a pump pressure under a shear failure pressure.
12. The method of claim 11, wherein the pump pressure is controlled
to prevent a tensile failure of the fractures.
13. The method of claim 1 further comprising allowing formation
rock faces of the subterranean formation to slip with respect to
each other.
14. The method of claim 1, wherein the particulate material is
Boehmite or Twaron.
15. The method of claim 1 further comprising measuring a flow
impedance pressure while pumping the temporary sealant, and
determining to stop pumping when the flow impedance pressure
reaches to a threshold pressure.
Description
[0001] The present application claims the benefit of and priority
to U.S. Provisional Patent Application Ser. No. 61/535,820,408
filed on Sep. 16, 2011, which is hereby incorporated by
reference.
FIELD
[0002] The present application relates to an enhanced geothermal
system (EGS) and to certain situations obtained in oil and gas
fields. More particularly, the present invention is a system and
method for providing temporary formation sealant,
BACKGROUND
[0003] In drilling wells for geothermal, oil and gas, and other
energy applications, circumstances arise where drilling fluid
enters into a fracture or voids in a rock formation due to high
porosity and/or permeability. This can result in the unwanted loss
of drilling fluid, also referred to as lost circulation. Lost
circulation is the loss of drilling fluid into fractures and other
openings or voids in the rock formation. These lost, circulation
zones, whether induced or naturally occurring, can he potentially
productive, especially in geothermal wells. When flowing into a
fracture or a void space in a formation, drilling fluid carries
materials such as bentonite, drill solids, barite, lost circulation
material (LCM), etc. These materials are difficult or impossible to
remove completely after the well has been drilled and completed. In
addition, the materials that flow into lost circulation zones may
modify the properties of the zone that are important for
maintaining permeability. The materials remaining in the lost
circulation zones impede or modify production of geothermal fluids,
it and gas. This results in reduced productivity of the well and
the ultimate economic value of the asset
[0004] Use of conventional circulation materials in the drilling
fluid or materials that are used as a separate treatment to seal
off the fluid losses can result in permanent damage even if they
treat and seal off the losses.
SUMMARY
[0005] A method and system for providing a temporary sealant within
a wellbore of a subterranean formation is disclosed. According to
one embodiment, the temporary sealant comprises a particulate
material and a liquid. The particulate material and the liquid are
mixed to a predetermined dilution ratio. The temporary sealant is
pumped into fractures via an open hole of the wellbore. The
particulate material accumulates and is left within the fractures
to set. Over a predetermined period of time, the particulate
material degrades, disintegrates, or dissolves within the
fractures.
[0006] The above and other preferred features, including various
novel details of implementation and combination of elements, will
now be more particularly described with reference to the
accompanying drawings and pointed, out in the claims, it will be
understood that the particular methods and apparatuses are shown by
way of illustration only and not as limitations. As will be
understood by those skilled, in the art, the principles and
features explained herein may be employed in various and numerous
embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The accompanying drawings, which are included as part of the
present specification, illustrate the presently preferred
embodiment of the present invention and together with the general
description given above and the detailed description of the
preferred embodiment given below serve to explain and teach the
principles of the present invention.
[0008] FIG. 1 illustrate a schematic view of an open hole fracture
in a wellbore, according to one embodiment;
[0009] FIG. 2 illustrates a schematic view of an exemplary process
for pumping a temporary formation sealant into open hole fractures,
according to one embodiment;
[0010] FIG. 3 illustrates a schematic view of an exemplary process
for circulating a sealant material out of an open hole, according
to one embodiment; and
[0011] FIG. 4 illustrates an exemplary process for filling
fractures with a temporary sealant, according to one
embodiment.
[0012] It should be noted that the figures are not necessarily
drawn to scale and that elements of structures or functions are
generally represented by reference numerals for illustrative
purposes throughout the figures. It also should be noted that the
figures are only intended to facilitate the description of the
various embodiments described herein. The figures do not describe
every aspect of the teachings described herein and do not limit the
scope of the claims.
DETAILED DESCRIPTION
[0013] A method and system for providing a temporary sealant within
a wellbore of a subterranean formation is disclosed. According to
one embodiment, the temporary sealant comprises a particulate
material and a liquid. The particulate material and the liquid are
mixed to a predetermined dilution ratio. The temporary sealant is
pumped into fractures via an open hole of the wellbore. The
particulate material accumulates and is left within the fractures
to set. Over a predetermined period of time, the particulate
material degrades, disintegrates, or dissolves within the
fractures.
[0014] In the following description, for purposes of clarity and
conciseness of the description, not all of the numerous components
shown in the schematic are described. The numerous components are
shown in the drawings to provide a person of ordinary skill in the
art a thorough enabling disclosure of the present invention. The
operation of many of the components would be understood to one
skilled in the art.
[0015] Each of the additional features and teachings disclosed
herein can be utilized separately or in conjunction with other
features and teachings to provide temporary formation sealant.
Representative examples utilizing many of these additional features
and teachings, both separately and in combination, are described in
further detail with reference to the attached drawings. This
detailed description is merely intended to teach a person of skill
in the art further details for practicing preferred aspects of the
present teachings and is not intended to limit the scope of the
claims. Therefore, combinations of features disclosed in the
following detailed description may not be necessary to practice the
teachings in the broadest sense and are instead taught merely to
describe particularly representative examples of the present
teachings.
[0016] Moreover, the various features of the representative
examples and the dependent claims may be combined in ways that are
not specifically and explicitly enumerated in order to provide
additional useful embodiments of the present teachings. In
addition, it is expressly noted that all features disclosed in the
description and/or the claims are intended to be disclosed
separately and independently from each other for the purpose of
original disclosure, as well as for the purpose of restricting the
claimed subject matter independent of the compositions of the
features in the embodiments and/or the claims. It is also expressly
noted that all value ranges or indications of groups of entities
disclose every possible intermediate value or intermediate entity
for the purpose of original disclosure, as well as for the purpose
of restricting the claimed subject matter. It is also expressly
noted that the dimensions and the shapes of the components shown in
the figures are designed to help understand how the present
teachings are practiced but are not intended, to limit the
dimensions and the shapes shown in the examples.
[0017] To overcome the problems associated with a lost circulation
zone, a temporary formation sealant system (TFSS) is provided. The
TFSS treats the lost circulation zone to become productive again
after the well has been drilled and completed. The TFSS seals off
the lost circulation zone in the open hole section of a well. Once
sealed, the hole is drilled to a target depth (TD) after the well
is completed. The temporary formation sealant degrades,
disintegrates, and/or dissolves over time. As the sealant
dissolves, the lost circulation zones regain original permeability
and flow capability. The lost circulation zone can he used for
production or stimulation of the well. The sealant flows from a
treated lost circulation zone, therefore the zone is essentially
undamaged from the treatment. Compared to an untreated well, the
well treated with TFSS remains productive and provides a viable
economic asset. If lost circulation zones were not properly sealed,
the value of the well could be greatly reduced and/or become
totally unproductive.
[0018] FIG. 1 illustrate a schematic view of an open hole fracture
110 in a wellbore, according to one embodiment. Wellbore 100 is
formed by drilling a hole into a subterranean formation. A metal
pipe (casing) 102 is suspended in the open hole 101 of wellbore 100
and secured by a cement section 105 between the casing 102 and the
open hole 101. A last casing shoe 103 is disposed at the bottom of
last casing 102. It is understood that open hole fracture 110 shown
in FIG. 1 represents any void space to be filled with a temporary
sealant, for example, multiple fractures or voids, or a porous or
permeable zone.
[0019] FIG. 2 illustrates a schematic view of an exemplary process
for pumping a temporary formation sealant into open hole fractures
110, according to one embodiment. Sealant material 120 is pumped
into open bole 101 to fill fractures or voids 110 within open hole
101. Open fractures or voids 110 are temporarily filled with
sealant material 120. Unlike conventional lost circulation
material, temporary sealant material 120 degrades, disintegrates,
and/or dissolves over time allowing the temporarily filled
fractures or voids 110 to reopen for production or injection.
Degraded, disintegrated, and/or dissolved sealant 120 enters the
drilling fluid or the natural subterranean pore fluid and exits the
formation via open hole 101 and/or fractures or voids 110, or
absorbed into the surrounding subterranean formulation.
[0020] FIG. 3 illustrates a schematic view of an exemplary process
for circulating a sealant material out of an open hole, according
to one embodiment. Sealant material 120 is pumped into fractures or
voids 101, accumulates in pore throats and fracture apertures, and
eventually prevents fluid movement. The residue of sealant material
120 and/or well fluid are circulated out of hole 101 during the
normal drilling or stimulation process. The circulation of the
residue of sealant material 120 does not require special treatment
or equipment.
[0021] Sealant material 120 remains in place as hole 101 is further
drilled to a total depth (ID) and/or completed. After a
predetermined period of time, sealant material 120 degrades,
disintegrates, and/or dissolves, leaving fractures or voids 110
reopen for production or injection as shown in FIG. 1. The
temporary sealant material slowly dearades in the fractures or
voids 110, eventually dissolving into the fluids in the rock or
diffusing into wellbore 100.
[0022] According to one embodiment, sealant material 120 is a fine
particulate material, small enough to flow into fractures or voids
110. A variety of materials may be used as sealant material 120
whether alone or in combination. For example, boehmite,
polypropylene carbonate, nolybisphenyl carbonate, poly lactic acid,
polyethylene terephthalate, and various para-aramids including but
not limited to Twaron.RTM. and Kevlar.RTM. may used for sealant
material 120. The particulate material is mixed with liquid (e.g.,
water) or dissolved into a solvent according to a predetermined
dilution ratio. The dilution ratio may be determined by operational
and/or well conditions, for example, the pumping capacity and/or
robustness of the pump used to pump the particulate mixture, size
and number, volume, and/or porosity of fractures or voids 110. For
example, the particulate material is diluted with a ratio of 3 to 1
or 4 to 1 (fluid to particulate material),
[0023] As sealant material 120 is pumped further into fracture or
voids 110, sealant material 120 reduces the permeability to the
point where the flow into the fractures or voids 110 is
significantly impeded. Impedance is measured by the well head and
pumping pressures. When the pumping pressure increases to a
threshold pressure that depends upon the particulars of the well
such as size and number, and/or volume of fractures or voids 110,
it is determined that the sealing has been accomplished. The liquid
is squeezed out of the particle pack as pressure continues to
apply. As a result, particulate sealant material 120 is left packed
off in the fractures or voids 120. The particle pack is able to
withstand a differential pressure from both within the fracture or
voids 110 and wellbore 100. Sealant material 120 remains intact
until it degrades, disintegrates, and/or dissolves over time. The
period of time for degradation, disintegration and/or dissolution
may be affected by temperature, pressure, and/or chemical
conditions as well as the material property of sealant material
120.
[0024] It is noted that oil and gas well (O&G) hydraulic
fracturing is significantly different from EGS hydroshearing
stimulation. The first major difference is that O&G hydraulic
fracturing typically involves applying enough pressure and stress
on the formation rock to cause tensile failure and create new
fractures. In EGS hydroshearing stimulation, however, pump pressure
is maintained at a shear failure pressure and is carefully
controlled and limited to prevent tensile failure. EGS
hydroshearing stimulation opens existing fractures and prevents the
creation of new fractures. Once the fracture is opened, the
formation rock faces can slip with respect to each other. When the
fractures close slightly after stimulation pressure is relieved,
the irregularities and disparities between the shifted formation
rock faces prevents the fractures from complete closure, leaving a
path for water flow with increased permeability.
[0025] The second major difference between O&G hydraulic
fracturing and EGS hydroshearirm stimulation is that sand and
chemicals are purposefully pumped into the open fractures in
O&G hydraulic fracturing to hold the fractures open and to aid
in the stimulation treatment. On the other hand, EGS stimulation
does not inject sand or other proppams into the formation nor are
chemicals typically added to the fracturing fluid to stimulate the
formations.
[0026] According to one embodiment, the present temporary formation
sealant system (TFSS) provides a number of unique and advantages.
Potentially productive formations within a well are temporarily
sealed to allow for production after the well has been drilled or
completed. Therefore, TFSS makes wells more productive and
increases final economic value of wells. TFSS can be used in oil,
gas, and geothermal wells without causing permanent damage to the
natural structure of the rock formation. Sealant materials used in
TFSS do not require special environment/I permitting, monitoring or
disposal nor drilling techniques or equipment other than that used
in conventional well drilling and mud-mixing. The sealant materials
may be designed to persist for a specified period of time allowing
more control over the drilling schedule.
[0027] The particulate sealant material is used in combination with
water or other solvent to seal off of the fracture and/or voids.
According, to one embodiment, the particulate sealant material is a
combination of organic compounds, inorganic compounds, natural or
synthetic minerals, or other materials. The material properties of
such combination result in controlled degradation, disintegration
or dissolution. By their nature and design, the particulate sealant
material used in TSFF leaves behind minimal residue and prevents
damage to the fractures or voids that would reduce permeability.
The particulate sealant material may be designed and mixed with
water or solvent at a concentration such that no products causing
health concerns are produced.
[0028] FIG. 4 illustrates an exemplary process for filling
fractures with a temporary sealant, according to one embodiment. A
temporary sealant is pumped into fractures or voids in a wellbore
(401). The temporary sealant is allowed to set within the fractures
or voids (402). The formulation is stimulated when applicable
before the temporary sealant degrades (403), and the open hole is
drilled or completed (404). The temporary sealant degrades,
disintegrates, or dissolves within the fractures or voids over a
time period (405). Once the temporary sealant degrades,
disintegrates, or dissolves, the wellbore is further treated for
production or stimulation (406).
[0029] Embodiments as described herein have significant advantages
over previously developed implementations. As will be apparent to
one of ordinary skill in the art, other similar apparatus
arrangements are possible within the general scope. The embodiments
described above are intended to be exemplary rather than limiting,
and the bounds should be determined from the claims.
* * * * *