Inhibiting Bridging In Annular Packs Within A Well

Abstract

Methods for placing an annular pack in a well include treating of the gravel in the annular pack to inhibit bridging and the formation of voids in the annular pack. The gravel can be treated to form a coating that improves the lubricity of the gravel. The gravel also can be treated with a surface-active agent. The treatment of the gravel inhibits clumping of the gravel particles which forms bridges in the annular pack.

Description

TECHNICAL FIELD

Embodiments of the technology relate generally to treatment of gravel placed in an annular pack within a well to reduce bridging and the formation of voids within the annular pack.

BACKGROUND

Wells are drilled into land and subsea formations in order to produce resources such as water and hydrocarbons (e.g., petroleum and natural gas). Annular packs are often placed in a producing section of the well along the perimeter of the well to inhibit the flow of sand from the formation into the well and/or to stabilize the formation surrounding the well. The annular packs can comprise gravel, which can include sand particles, ceramic particles, proppant particles, or other similar particles. As the gravel is placed in the well to form the annular pack, the gravel particles can adhere to one another forming bridges in the annular space within the well. The bridges cause undesirable voids to form within the annular pack. Accordingly, techniques for inhibiting the formation of bridges in the annular packs would be beneficial.

SUMMARY

Generally, the techniques described herein can be applied to a variety of situations in which gravel is placed in an annular pack within a well.

In one example embodiment, a method of placing an annular pack in a well comprises: (i) applying a lubricity coating to gravel to produce coated gravel; (ii) incorporating the coated gravel into a carrier fluid at a surface of the well; (iii) injecting the carrier fluid comprising the coated gravel into the well; and (iv) placing the coated gravel along a perimeter of the well to form an annular pack.

In another example embodiment, a method of placing an annular pack in a well comprises: (i) applying a curable coating to gravel; (ii) curing the curable coating to produce coated gravel; (iii) incorporating the coated gravel into a carrier fluid at a surface of the well; (iv) injecting the carrier fluid comprising the coated gravel into the well; and (iv) placing the coated gravel along a perimeter of the well to form an annular pack.

In yet another example embodiment, a method of placing an annular pack in a well comprises: (i) treating gravel with a surface-active agent to produce treated gravel; (ii) injecting a carrier fluid comprising the treated gravel into the well; and (iii) placing the coated gravel along a perimeter of the well to form an annular pack.

The foregoing embodiments are non-limiting examples and other aspects and embodiments will be described herein. The foregoing summary is provided to introduce various concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify required or essential features of the claimed subject matter nor is the summary intended to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate only example embodiments relating to inhibiting bridging within an annular pack in a well and therefore are not to be considered limiting of the scope of this disclosure. The principles illustrated in the example embodiments of the drawings can be applied to alternate methods and apparatus. Additionally, the elements and features shown in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the example embodiments. Certain dimensions or positions may be exaggerated to help visually convey such principles. In the drawings, the same reference numerals used in different embodiments designate like or corresponding, but not necessarily identical, elements.

FIG. 1 illustrates a portion of a well with an annular pack in which bridging has occurred.

FIG. 2 illustrates a portion of a well with an annular pack comprising gravel that has been treated in accordance with an example embodiment of the disclosure.

FIG. 3 illustrates a method of placing an annular pack comprising coated gravel in a well in accordance with an example embodiment of the disclosure.

FIG. 4 illustrates another method of placing an annular pack comprising coated gravel in a well in accordance with an example embodiment of the disclosure.

FIG. 5A illustrates a method of placing an annular pack comprising treated gravel in a well in accordance with an example embodiment of the disclosure.

FIG. 5B illustrates another method of placing an annular pack comprising treated gravel in a well in accordance with an example embodiment of the disclosure.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

The example embodiments discussed herein are directed to compositions and methods for inhibiting bridging in the annular packs placed in a well. As referenced above, the annular packs can comprise gravel, which can include sand particles, ceramic particles, proppant particles, or other similar particles. As used herein, the term “gravel” should be understood to include any one or more of the foregoing particles. As examples, the annular pack can be a gravel pack used in an open hole well, or the annular pack can be a pack used in a cased and perforated well, or the annular pack can be assembled around a screen in a hydraulic fracturing or frac-pack operation. As the gravel is placed in the well to form the annular pack, the gravel particles can adhere to one another forming bridges in the annular space within the well. The increased viscosity of carrier fluids used to place the annular pack in the well can contribute to the gravel particles adhering to one another and forming bridges. The bridges prematurely formed before a complete annular gravel pack is achieved can cause undesirable voids to form within the annular pack. The formation of voids in the annular pack can negatively affect the function of the annular pack and the production of fluids from the well.

This problem is illustrated in FIG. 1. FIG. 1 illustrates a cross-section of a portion of an example well 105. The wellbore 116 is the perimeter of the well 105 along the face of the formation 110 into which the well is drilled. This example well 105 includes a casing 117 along the wellbore 116 and a plug 115 at the base of the well 105. The casing 117 includes perforations 113 through which fluids are produced from the formation 110 into the well 105. A tubing 114 is located in the well for conveying produced fluids (e.g., oil, natural gas) from the formation 110 upwards through the well 105 to the surface. In the producing section of the well adjacent to the perforations 113, a screen 107 and an annular pack 112 are located. The annular pack 112 comprises gravel and is located in the annulus between the screen 107 and the casing 117. The annular pack 112 and the screen 107 can stabilize the well in the area adjacent the perforations and can filter sand in the produced fluid flowing from the formation 110 into the well.

FIG. 1 also illustrates the problem of undesirable bridging in the annular pack 112. Specifically, bridging occurs when the gravel particles adhere together in clumps instead of the desired uniform distribution of the gravel particles. FIG. 1 shows that the gravel particles of the annular pack 112 have adhered together near the bottom of the annular pack 112 causing a bridge 120. The bridge 120 prevents the gravel particles from filling the annulus between the screen 107 and the perforated casing, thereby causing a void 122. The existence of the void 122 can negatively affect the integrity of the well. For example, the existence of a void in the annular pack can contribute to erosion in the wellbore and, potentially, failure of the well. The existence of a void can also negatively impact production of fluids from the well, for example, by causing unpredictable pressure differentials in the wellbore. Accordingly, techniques for inhibiting the bridging of gravel in annular packs would be beneficial for the operation of wells.

The following description provides example embodiments for inhibiting the formation of bridging in an annular pack in a well. Specifically, the example embodiments describe several techniques for treating the gravel that is placed in an annular pack. The treatments described herein can increase the lubricity of the gravel particles, thereby decreasing the likelihood of the gravel particles adhering to one another and forming a bridge in the annular pack. Therefore, the example techniques described herein can improve the performance of a well. As will be described further in the following examples, the compositions and methods described herein improve upon prior art approaches to placing an annular pack in a well.

In the following paragraphs, particular embodiments will be described in further detail by way of example with reference to the drawings. In the description, well-known components, methods, and/or processing techniques are omitted or briefly described. Furthermore, reference to various feature(s) of the embodiments is not to suggest that all embodiments must include the referenced feature(s).

FIG. 2 illustrates an example of a well in which one of the gravel treatment techniques described herein has been applied to the gravel in the annular pack, thereby inhibiting bridging and improving the well. FIG. 2 is similar to FIG. 1 in that it illustrates a cross-section of an example well 205. The well 205 is located in a formation 210 and can be located on land or can be an underwater or offshore well. Example well 205 includes a casing 217 along the wellbore 216 and a plug 215 at the base of the well 205. The casing 217 includes perforations 213 through which fluids are produced from the formation 210 into the well 205. A tubing 214 is located in the well for conveying produced fluids (e.g., oil, natural gas) from the formation 210 upwards through the well 205 to the surface. In the producing section of the well adjacent the perforations 213, a cylindrical screen 207 and an annular pack 212 are located. The annular pack 212 comprises gravel and is located in the annulus between the cylindrical screen 207 and the cylindrical casing 217 such that the annular pack is in direct contact with the screen 207 and the casing 217. The annular pack 212 and the screen 207 can stabilize the well in the area adjacent the perforations and can filter sand in the produced fluid flowing from the formation 210 into the well.

In contrast to the well 105 of FIG. 1, the gravel of the annular pack 212 in FIG. 2 has been treated by one of the methods further illustrated in the examples provided below. The initial treatment of the gravel before placement into the annular pack 212 of FIG. 2 has inhibited bridging and the formation of voids in the annular pack. In FIG. 2, the gravel of the annular pack is evenly distributed without bridging and voids.

While well 205 is typical of an annular pack for a hydraulic fracturing operation, the techniques described herein for treating the gravel of an annular pack can be applied to other types of wells and other configurations. For example, the same techniques described herein for treating the gravel of an annular pack can be used in an open hole well where no casing is present. In other words, the annular pack would be located in the annulus between a screen and a face of the formation such that it is in direct contact with the screen and the face of the formation at the wellbore.

Referring now to FIG. 3, an example method 300 is provided. Method 300 provides an example method for treating gravel and placing the gravel in an annular pack in a well. Operation 302 of method 300 involves applying a lubricity coating to gravel to produce a coated gravel. The lubricity coating can be a variety of materials. As one example, the lubricity coating can be a hydrophobic coating, which can inhibit gravel particles from adhering together and forming bridges in the annular pack. The lubricity coating can be applied to the gravel at a warehouse remote from the wellsite or the lubricity coating can be applied proximate to the well in which the gravel will be injected. When the lubricity coating is a hydrophobic coating, it is preferably applied to the gravel particles using an agitation method in a low humidity environment.

As a more specific example, the lubricity coating can be a hydrophobic organosilane coating. The alkyl functionality of the organosilane can include linear or branched saturated alkane groups, partially fluorinated alkane groups, or partially unsaturated alkanes. The silane functionality can include trihalo, such as trichloro, trialkoxy, and other silanes known to those skilled in the art.

As yet another example, it may be desirable to remove the lubricity coating from the gravel particles once a proper annular pack has been formed. In such an example, the lubricity coating on the gravel particles can be degradable such that it is degraded after the treated gravel is placed in the well forming the annular pack. In such an example, the lubricity coating can be a hydrophobic alkane coating with a degradable linkage, such as an amide, imide, or ester. The degradable linkage can begin to degrade when exposed to a trigger in the well, such as water, heat, or a particular pH.

Referring again to example method 300, once the gravel has been coated, the coated gravel is added to a carrier fluid at the surface outside the well in operation 304 and the carrier fluid with the coated gravel is injected into the well in operation 306. The carrier fluid carries the coated gravel down the well to the location where the annular pack is to be placed. In operation 308, the carrier fluid deposits the coated gravel along the perimeter of the well forming the annular pack in the desired location. The annular pack typically will be formed in the annulus between a cylindrical screen and the cylindrical casing in the well. Because the gravel has been coated to improve lubricity, the gravel particles will be less likely to adhere together and form unwanted bridges in the annular pack.

Referring now to FIG. 4, another example method 400 is provided. Method 400 provides another example method for treating gravel and placing the gravel in an annular pack in a well. Operation 402 of method 400 involves applying a curable coating to gravel to produce a coated gravel. The curable coating can be any of a variety of coatings that can be cured to form a hard coating on the exterior of the gravel particles. Such coatings can be any of a variety of polymers, including resins. In operation 403, the curable coating is cured to form the coated gravel wherein the gravel particles will have a hard coating. The resulting cured-coated material is often referred to as a pre-cured resin-coated gravel. The coating can improve the lubricity of the gravel particles to reduce the likelihood the gravel particles will adhere together when in the annular pack.

In operation 404, the pre-cured coated gravel is added to a carrier fluid at the surface of the well and in operation 406 the carrier fluid comprising the coated gravel is injected into the well. The carrier fluid carries the coated gravel down the well to the location where the annular pack should be placed. In operation 408, the carrier fluid deposits the coated gravel along the perimeter of the well forming the annular pack in the desired location. The annular pack typically will be formed in the annulus between a cylindrical screen and the cylindrical casing in the well. Because the gravel has been coated to improve lubricity, the gravel particles will be less likely to adhere together and form unwanted bridges in the annular pack.

Similar to the example of method 300, in some cases it may be desirable to remove the cured coating from the gravel particles once a proper annular pack has been formed. In such an example, the cured coating on the gravel particles can be degradable such that it is degraded after the coated gravel is placed in the well forming the annular pack. The curable coating can be selected so that it degrades when exposed to one or more of a variety of triggers, such as water, heat, or a particular pH.

Method 500 of FIG. 5A and method 550 of FIG. 5B both involve treating gravel particles with a surface-active agent, such as a surfactant, to improve the lubricity of the gravel particles. For example, a surface-active agent can be chosen that causes the gravel particles to be hydrophobic. In operation 502 of method 500, a surface-active agent is mixed with gravel to produce treated gravel. Unlike the coatings of previous methods 300 and 400 that formed chemical or mechanical bonds to the gravel particles, the surface-active agent is associated with the gravel particles. For example, the untreated gravel may have a negative charge and a surface-active agent have a positive charge will be attracted to gravel particles.

Once the gravel has been treated with the surface-active agent, the treated gravel is added to a carrier fluid at the surface outside the well in operation 504 and the carrier fluid with the treated gravel is injected into the well in operation 506. The carrier fluid carries the treated gravel down the well to the location where the annular pack is to be placed. In operation 508, the carrier fluid deposits the treated gravel along the perimeter of the well forming the annular pack in the desired location. The annular pack typically will be formed in the annulus between a cylindrical screen and the cylindrical casing in the well. Because the gravel has been treated to improve lubricity, the gravel particles will be less likely to adhere together and form unwanted bridges in the annular pack.

Referring to method 550 of FIG. 5B, in operation 552 gravel particles are added to a carrier fluid at a surface of a well. The carrier fluid can contain a surface-active agent that is mixed with the gravel in operation 554. The surface-active agent can associate with the gravel particle surfaces forming a carrier fluid with treated gravel particles. In operation, 556, the slurry of carrier fluid with the treated gravel particles is injected into the well. The carrier fluid carries the treated gravel down the well to the location where the annular pack is to be placed. In operation 558, the carrier fluid deposits the treated gravel along the perimeter of the well forming the annular pack in the desired location. The annular pack typically will be formed in the annulus between a cylindrical screen and the cylindrical casing in the well. Because the gravel has been treated to improve lubricity, the gravel particles will be less likely to adhere together and form unwanted bridges in the annular pack.

It should be understood that the foregoing example methods of FIGS. 3, 4, 5A, and 5B can be modified within the scope of this disclosure. For example, certain steps of the example methods may be altered. Moreover, additional steps may be added in sequence or in parallel in the example methods.

For any figure shown and described herein, one or more of the components may be omitted, added, repeated, and/or substituted. Accordingly, embodiments shown in a particular figure should not be considered limited to the specific arrangements of components shown in such figure. Further, if a component of a figure is described but not expressly shown or labeled in that figure, the label used for a corresponding component in another figure can be inferred to that component. Conversely, if a component in a figure is labeled but not described, the description for such component can be substantially the same as the description for the corresponding component in another figure.

With respect to the example methods described herein, it should be understood that in alternate embodiments, certain steps of the methods may be performed in a different order, may be performed in parallel, or may be omitted. Moreover, in alternate embodiments additional steps may be added to the example methods described herein. Accordingly, the example methods provided herein should be viewed as illustrative and not limiting of the disclosure.

Terms such as “first”, “second”, “top”, “bottom”, “side”, “distal”, “proximal”, and “within” are used merely to distinguish one step or component from another. Such terms are not meant to denote a preference or a particular orientation, and are not meant to limit the embodiments described herein. In the example embodiments described herein, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to one of ordinary skill in the art that the invention may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.

The terms “a,” “an,” and “the” are intended to include plural alternatives, e.g., at least one. The terms “including”, “with”, and “having”, as used herein, are defined as comprising (i.e., open language), unless specified otherwise.

When Applicant discloses or claims a range of any type, Applicant's intent is to disclose or claim individually each possible number that such a range could reasonably encompass, including end points of the range as well as any sub-ranges and combinations of sub-ranges encompassed therein, unless otherwise specified. Numerical end points of ranges disclosed herein are approximate, unless excluded by proviso.

Values, ranges, or features may be expressed herein as “about”, from “about” one particular value, and/or to “about” another particular value. When such values, or ranges are expressed, other embodiments disclosed include the specific value recited, from the one particular value, and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that there are a number of values disclosed therein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. In another aspect, use of the term “about” means ±20% of the stated value, ±15% of the stated value, ±10% of the stated value, ±5% of the stated value, ±3% of the stated value, or ±1% of the stated value.

Although embodiments described herein are made with reference to example embodiments, it should be appreciated by those skilled in the art that various modifications are well within the scope of this disclosure. Those skilled in the art will appreciate that the example embodiments described herein are not limited to any specifically discussed application and that the embodiments described herein are illustrative and not restrictive. From the description of the example embodiments, equivalents of the elements shown therein will suggest themselves to those skilled in the art, and ways of constructing other embodiments using the present disclosure will suggest themselves to practitioners of the art. Therefore, the scope of the example embodiments is not limited herein.

Claims

1. A method of placing an annular pack in a well, the method comprising: apply a lubricity coating to gravel to produce coated gravel;incorporate the coated gravel into a carrier fluid at a surface of the well;inject the carrier fluid comprising the coated gravel into the well; andplace the coated gravel along a perimeter of the well to form an annular pack.

2. The method of claim 1, wherein the lubricity coating is a hydrophobic material.

3. The method of claim 1, wherein the lubricity coating is a hydrophobic organosilane.

4. The method of claim 1, wherein the lubricity coating is applied to the gravel using an agitation process in which humidity is minimized.

5. The method of claim 1, further comprising degrading the lubricity coating on the coated gravel after the annular pack is in place in the well.

6. The method of claim 1, wherein the annular pack is located between and contacts a screen and a casing in the well.

7. The method of claim 1, wherein the annular pack is located between and contacts a screen and a formation wall in the well.

8. A method of placing an annular pack in a well, the method comprising: apply a curable coating to gravel;cure the curable coating to produce coated gravel;incorporate the coated gravel into a carrier fluid at a surface of the well;inject the carrier fluid comprising the coated gravel into the well; andplace the coated gravel along a perimeter of the well to form an annular pack.

9. The method of claim 8, wherein the curable coating is a polymer.

10. The method of claim 8, wherein, after curing, the curable coating increases the lubricity of the gravel.

11. The method of claim 8, wherein, after curing, the curable coating forms an inert coating on the gravel.

12. The method of claim 8, further comprising degrading the lubricity coating on the coated gravel after the annular pack is in place in the well.

13. The method of claim 8, wherein the annular pack is located between and contacts a screen and a casing in the well.

14. The method of claim 8, wherein the annular pack is located between and contacts a screen and a formation wall in the well.

15. A method of placing an annular pack in a well, the method comprising: treat gravel with a surface-active agent to produce treated gravel;inject a carrier fluid comprising the treated gravel into the well; andplace the coated gravel along a perimeter of the well to form an annular pack.

16. The method of claim 15, wherein the gravel is treated with the surface-active agent before the gravel is incorporated into the carrier fluid.

17. The method of claim 15, wherein the surface-active agent is a surfactant.

18. The method of claim 15, wherein the surface-active agent causes the treated gravel to be hydrophobic.

19. The method of claim 15, wherein the annular pack is located between and contacts a screen and a casing in the well.

20. The method of claim 15, wherein the annular pack is located between and contacts a screen and a formation wall in the well.