WO2017075139A1

WO2017075139A1 - Enhanced hydraulic fracturing of geological formations

Info

Publication number: WO2017075139A1
Application number: PCT/US2016/059001
Authority: WO
Inventors: Baoyan Li; Alberto G. MEZZATESTA; Michael R. Wells
Original assignee: Intellectual Property Counsel
Priority date: 2015-10-27
Filing date: 2016-10-27
Publication date: 2017-05-04

Abstract

An oil well or gas well may be completed or stimulated by employing a hydraulic fracturing process within a wellbore to create, reopen, or propagate fractures within a geological formation; and creating at least one gas shock wave thereby vibrating rock within the geological formation and/or blowing fracture fluid further into the geological formation. The gas shock wave can function to enhance the fractures within the geological formation. Additionally, employment of such a Shockwave can reduce the cost of the hydraulic fracturing process.

Description

Title: ENHANCED HYDRAULIC FRACTURING OF

GEOLOGICAL FORMATIONS

Inventor: LI, Baoyan; MEZZATESTA, Alberto G.; and WELLS,

Michael R.

BACKGROUND

1. Field of the Disclosure

[0001] The invention relates to oil and gas well stimulation. The invention particularly relates to oil and gas well stimulation performed using hydraulic fracturing.

2. Background Of The Disclosure

[0002] Generally speaking, there are several techniques utilized to stimulate well and gas production by hydraulic fracturing which is sometimes referred to in the art as 'Tracing or fracking." In one such method, a packer or plug is utilized to isolate a particular portion of the well and the fracking fluid is injected into the isolated portion under high pressure. Once a given portion of the well is treated in this manner, a second or even more zone(s) uphole of the first zone is/are isolated by a another packer or plug that cuts off flow to the downhole portion of the well that has been treated

[0003] Such processes are well known in the art. For example, U.S. Pat. Nos. 7,322,417; 7, 134,505; and 9, 163,494 all disclose such processes. These patents are all incorporated herein in their entirety by reference.

[0004] One limitation of hydraulic fracturing is the dissipation of energy as fracturing occurs. While fracturing operations are on the whole very impressive, there is a finite limit on the amount of force that could be introduced downhole to create and then propagate fractures in a geological formation.

[0005] It would be desirable in the art to be able to enhance the fracturing capability of a hydraulic fracturing operation. It would be especially desirable in the art if such an enhancement was both efficient and cost-effective. SUMMARY

[0006] In one aspect, the invention is a method for stimulating and/or completing an oil and gas well comprising: employing a hydraulic fracturing process within a wellbore to create, reopen, or propagate fractures within a geological formation; and creating at least one gas shock wave thereby vibrating rock within the geological formation and/or blowing fracture fluid further into the geological formation; wherein the gas shock wave functions to enhance the fractures within the geological formation.

[0007] In another aspect, the invention is such a method wherein the gas shock wave is employed at the beginning of a hydraulic fracturing process.

[0008] In still another aspect, the invention is such a method wherein the gas shock wave is employed during a hydraulic fracturing process.

[0009] Another aspect of the invention is such a method wherein the gas shock wave is employed at the end of a hydraulic fracturing process.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment 10 and the accompanying drawings in which:

Figure 1 is a flow chart showing a first embodiment of the method of the application wherein a gas shock wave is employed during a hydraulic fracturing process;

Figure 2 is a flow chart showing a second embodiment of the method of the application wherein a gas shock wave is employed at the beginning of a hydraulic fracturing process;

Figure 3 is a flow chart showing a third embodiment of the method of the application wherein a gas shock wave is employed at the end of a hydraulic fracturing process; and

Figure 4 is a flow chart showing a fourth embodiment of the method of the application wherein a gas shock wave is employed twice or more during a hydraulic fracturing process. DESCRIPTION

[0011] In one embodiment, the invention is a method for stimulating and/or completing an oil or gas well comprising: employing a hydraulic fracturing process within a wellbore to create, reopen, or propagate fractures within a geological formation; and creating at least one gas shock wave thereby vibrating rock within the geological formation and/or blowing fracture fluid further into the geological formation; wherein the gas shock wave functions to enhance the fractures within the geological formation.

[0012] For the purposes of this application, the term "hydraulic fracturing process" means any process for stimulating and/or completing or otherwise treating an oil well or gas well employing hydraulic fracturing (fracturing the rock within a geological formation using high pressure liquids). Such commercial processes are well known in the art and have already been incorporated by reference in this application. Specifically, the use of this term within this application includes both conventional fracking as employed for single wells and specialized fracking of formations producing natural gas from tight shales.

[0013] For the purposes of this application, the term "stimulating" when used in the context of treating an oil well has its normal meaning within the art, namely performing an action to increase the flow of hydrocarbons in an oil well or gas well. Similarly, the term "completing" has its normal meaning within the art, namely making a drilled well ready for production.

[0014] In the normal course of producing oil or gas, the hydrocarbon, often in the presence of brine, enters a wellbore through fractures in the surrounding geological formation. While often initially created using explosive charges during the perforation of the casing, the fractures may be extended further into the formation and enlarged by the hydraulic fracturing process.

[0015] In employing the process of the present application, the hydraulic fracturing process can be enhanced. For the purposes of this application, the term "enhanced" means more effectively fracturing the formation. This can mean that the fractures are wider, extend more deeply into the geological formation, or both; as compared to a hydraulic fracturing process performed without practicing the method of the present application. Such an enhancement, in some embodiments, may also lower the overall costs of performing the stimulation or merely improve the results of the stimulations on a per dollar basis or save the cost to refrac the formation.

[0016] The well stimulation method of the present application can be performed in a two-step procedure. One of these 2 steps is to generate hydraulic fractures with the current hydraulic fracturing technique with/without proppants.

[0017] The other of these 2 steps is to generate single/multiple gas shock(s) to enhance the complex fracture network by vibrating rock and blowing the fracturing fluid further into the geological formation.

[0018] Note that the steps can be performed in either order or even simultaneously.

[0019] Any gas known to those of ordinary skill in the art which can be safely introduced into a geological formation may be employed with the method of the application. An additional requirement of at least some embodiments is that the gas employed is one that does not sublime nor require an excessive amount of energy to vaporize from a liquid form. For this reason, in some embodiments, carbon dioxide and ammonia should not be used with the method of the application.

[0020] Preferred gases to be used with the method of the application include nitrogen, oxygen depleted air, and in some embodiments atmospheric air.

[0021] While, in some embodiments, the gases to be used with the method of the application may be introduced from the surface, it may be desirable that the gas be introduced downhole in a highly pressurized state first. In one such embodiment, the gas is introduced downhole employing a high-pressure gas container. The gas may be released from the high-pressure gas container by any means known to be useful to those of ordinary skill in the art that would generate a shock wave. For example, in one embodiment, this could be accomplished by employing an explosive charge, not unlike that which is found in a perforating gun.

[0022] In the practice of the method of the application, the gas to be employed is conveyed to and then released within the stimulated zone of the wellbore to create an instantly delivered high-pressure impulse, often in the form of a shock wave (sometimes referred to in the art as a "water hammer"). [0023] Once released, the gas flows into the hydraulic fracture network and delivers the energy which can, in some embodiments be controlled such that it occurs at a specific time. This allows the operator performing the method to control where in the fracturing process the shock wave occurs.

[0024] The shock wave traverses through the fracturing fluid to boost the hydraulic capacity of the already generated hydraulic fractures and, in some embodiments, activate the natural fractures encountered in the stimulated zone of the wellbore.

[0025] The method of the application can be used at the beginning, during and/or at the end of the fracture stimulation process to boost the hydraulic fractures and assist in fracturing new rock or even a rock that would not otherwise be fractured. In one embodiment, the method of the application can be implemented one single time. In other embodiments of the application, the method of the application can be used to deliver a shock wave multiple times during the stimulation process.

[0026] The advantages or potential benefits of the method of the application are several. One advantage may be an increased contact area between the stimulated well and the formation. Another such advantage might be more open residual fractures due to shifted rock layers. Still another advantage may be improved proppant distributions. In yet another advantage may be reduction of proppant quantity by keeping the residual fractures open through the process of slippage between the rough-rock fracture surfaces. Finally, another advantage of the method of the application may be activation of natural fractures due to air shock.

[0027] Turning now to Figure 1, Figure 1 is a flow chart showing a first embodiment of the method of the application wherein a gas shock wave is employed during a hydraulic fracturing process. In this embodiment, the shock wave is introduced after the fracturing process has begun but prior to its completion.

[0028] Figure 2 is a flow chart showing a second embodiment of the method of the application wherein a gas shock wave is employed at the beginning of a hydraulic fracturing process. In such embodiments, the Shockwave may be employed prior to the initiation of hydraulic fracturing or it may occur at the same instance as the beginning of the hydraulic fracturing. [0029] Turning now to Figure 3, this is a flow chart showing a third embodiment of the method of the application wherein a gas shock wave is employed at the end of a hydraulic fracturing process. In an embodiment such as this, the Shockwave may be employed after the fracturing process has been fully completed or it may be employed concurrently with the termination of the fracturing process.

[0030] Figure 4 is a flow chart showing a fourth embodiment of the method of the application wherein a gas shock wave is employed twice during a hydraulic fracturing process. The purpose of this flowchart is to illustrate that the gas shock wave may be employed multiple times during a hydraulic fracturing process.

[0031] In most embodiments of the method of the application, the duration of the gas release will be quite brief. In order to achieve the maximum Shockwave; the gas will be conveyed to the borehole as quickly as possible and in it as high-pressure as possible. Such an embodiment would of course include use of a high-pressure gas container. It would especially include a rupture of such a container, similar to one wherein an explosive charge was employed to rupture the container.

Claims

1. A method for stimulating and/or completing an oil or gas well comprising: employing a hydraulic fracturing process within a wellbore to create, reopen, or propagate fractures within a geological formation; and creating at least one gas shock wave thereby vibrating rock within the geological formation and/or blowing fracture fluid further into the geological formation;

wherein the gas shock wave functions to enhance the fractures within the geological formation.

2. The method of Claim 1 wherein the gas Shockwave is created prior to employing the hydraulic fracturing process.

3. The method of Claim 1 wherein the gas Shockwave is created after employing the hydraulic fracturing process.

4. The method of Claim 1 wherein the gas Shockwave is created during the hydraulic fracturing process.

5. The method of Claim 4 wherein the gas Shockwave is created multiple times during the hydraulic fracturing process.

6. The method of Claim 1 wherein the gas Shockwave is created using nitrogen or oxygen depleted air.