Patent Application
20250027379
Disclosed are systems and methods for diversion in multistage fracturing systems pumping operations. Specifically, disclosed are systems and methods for using a combination of date palm seeds and rock salt diversion systems as diverters to redirect fluids during multistage frac pumping operations.
Multistage fracturing (MSF) systems are lower completions run inside wells to allow for stimulation operations to be performed across multiple intervals, as desired. The MSF system is a ball and seat completion that consists of frac sleeves, packers and requires a ball to drop to active the specific sleeve that requires stimulation. A frac sleeve is activated by dropping a ball into a port and applying a specific pressure. Once the sleeve is activated, stimulation fluids can be pumped into the required zone.
The objective of a packer in an MSF completion is to provide the required isolation between stages in a system that has more than one stage to be attended. A second stage can be activated by dropping a ball that matches the port size specification, where the ball will act at the same time as an isolation within the wellbore guiding fluids to be pumped into the second stage instead of the previous stage.
MSF systems can be for both acid and proppant stimulations. In a normal acid stimulation with an MSF system, once the ball is dropped to isolate the first stage, the packer behind the wellbore performs its duty and isolates the fluids from going to the previously stimulated zone. However, packer failure is very common in acid stimulations due to acid reaction with packer's elements causing communication between stages, leading stimulation fluids to go to both stages.
There are some options to mitigate the communication between stages. One of these options is installing multiple packers to ensure isolation even if one of the packers do fail. Another option is to attempt and pump fluids and material when failure is confirmed, to try and plug the leak in the packer to create a temporary isolation. This temporary isolation should help create a differential pressure and send fluids to the new stage instead of the previous one.
Disclosed are systems and methods for diversion in multistage fracturing systems pumping operations. Specifically, disclosed are systems and methods for using a combination of date palm seeds and rock salt diversion systems as diverters to redirect fluids during multistage frac pumping operations.
In a first aspect, a method for diversion in multistage fracturing is provided. The method includes the steps of identifying an isolation failure between stages in a wellbore due to a point of failure, pumping a diversion mixture into the wellbore, plugging the point of failure with the diversion mixture, pumping a spacer fluid through the wellbore, and pumping an acid stimulation fluid through the wellbore to a frac sleeve upstream of the point of failure.
In certain aspects, the point of failure is a packer. In certain aspects, the step of identifying an isolation failure occurs after a frac sleeve is deployed upstream of the point of failure. In certain aspects, the diversion mixture includes water, date palm seeds and rock salts. In certain aspects, the diversion mixture temporarily plugs the point of failure before isolation failure occurs again. In certain aspects, the spacer fluid is selected from water, a gel, and a combination of the same.
In a second aspect, a composition for diversion in isolation failure between stages is provided. The composition includes date palm seeds and rock salts. In certain aspects, the composition further includes water.
These and other features, aspects, and advantages of the scope will become better understood with regard to the following descriptions, claims, and accompanying drawings. It is to be noted, however, that the drawings illustrate only several embodiments and are therefore not to be considered limiting of the scope as it can admit to other equally effective embodiments.
In the accompanying FIGURES, similar components or features, or both, may have a similar reference label.
While the scope of the apparatus and method will be described with several embodiments, it is understood that one of ordinary skill in the relevant art will appreciate that many examples, variations and alterations to the apparatus and methods described here are within the scope and spirit of the embodiments.
Accordingly, the embodiments described are set forth without any loss of generality, and without imposing limitations, on the embodiments. Those of skill in the art understand that the scope includes all possible combinations and uses of particular features described in the specification.
The systems and methods provide a combination of date palm seeds and rock salt diversion systems in acid fracturing operations to mitigate communication between stages in multistage fracturing. The combination of date palm seeds and rock salt as a diversion mixture in a diverter system helps to redirect fluids during multistage frac pumping operations, where isolate failure occurs between stages.
As used throughout, “frac sleeves” or “fracturing sleeves” refer to physical devices inserted into a well before fracturing begins to isolate sections of the wellbore.
As used throughout, “rock salts” refers to sodium chloride (NaCl) angular salt. The rock salts can be in various sizes as needed.
An embodiment of the diverter system is described with reference to
After the first stage stimulation through frac sleeve 10 has occurred, packer 30 operates to isolate the first stage inside the annulus. A ball is dropped to frac sleeve 20 inside the wellbore, which isolates the first stage from inside the wellbore and activates the second stage. The dropped ball matches the port size specification of frac sleeve 20. A diversion step occurs when it is discovered that isolation of packer 30 has failed. When isolation of packer 30 fails, communication between the first stage and second stage occurs and fluids are pumped into both stages. When it is discovered that isolation has failed, a diversion mixture is pumped or bullheaded through the wellbore. The initial injection rate of the diversion mixture can be 10 barrels per minute. The diversion mixture includes an aqueous mixture of date palm seeds and rock salt. The date palm seeds and rock salt serve as solid diverters. The water is a carrier enabling the date palm seeds and rock salt to be carried to the point of failure. The diversion mixture temporarily restores the isolation capability of packer 30 allowing acid stimulation to occur in the second stage. The length of time that isolation is restored depends on the formation pressure, formation temperature, and rate at which the diversion mixture is pumped. The solid diverters of the date palm seeds and rock salt can cause permanent formation damage that cannot be fixed and that damage can contribute to the temporary nature of restoring the isolation capability of a packer. However, the dissolvable nature of the solid diverters allows for acid to pass through and production to continue from the formation. By isolating the point of failure for a period of time, the new stage will be treated for a longer period than if isolation was not restored and both stages produced simultaneously. Advantageously and unexpectedly, the use of the diversion mixture increases overall production by increasing production in the new stage in which production had not yet occurred.
After the diversion mixture plugs the point of failure and isolation is restored a space fluid is pumped through the wellbore. The spacer fluid can be any type of spacer fluid suitable for use in an acid stimulation. The spacer fluid can prevent components in the diversion mixture from reacting with components in the acid stimulation fluid. The spacer fluid can include water, a gel, or combinations of the same. In at least one embodiment, the spacer fluid contains a gel carried in water. The flow rate of the spacer fluid can depend on the formation properties.
Following injection of the spacer fluid the acid stimulation fluid is pumped through the wellbore. The acid stimulation fluid treats the second stage, or the stage created when isolation is restored due to the solid diverters plugging the packer. The date palm seeds can react with acid stimulation fluid. The rock salt can react with the acid stimulation fluid. The flow rate of the acid stimulation fluid can depend on the formation properties, the size of the stage, and other conditions.
Date palm seeds suitable for use in the diversion mixture can have the properties and be prepared by the methods described in U.S. Pat. Nos. 10,457,846 and 11,041,347, both of which are incorporated herein by reference in their entirety. The size of data palm seeds used depends on the size of the packers and ports in the packers. The methods and systems described result in the date palm seeds plugging a failed packer. The diversion mixture does not plug the formation itself. By plugging a failed packer, the diversion mixture creates a flow path for acids to stimulate new zones.
Advantageously and unexpectedly, the combination of date palm seeds and rock salts have a synergistic effect in restoring isolation. Rock salts alone are not effective to plug the packer because at the pressures and temperatures in the formation they will dissolve before the isolation of the stage can occur. In addition, large volumes of rock salts would be required. Advantageously, the mixture of date palm seeds and rock salts overcome the deficiencies of rock salts alone by creating enough differential pressure to drive stimulation fluids into a new stage and frac that stage.
Advantageously, the instant method includes only one packer between the stages and is in the absence of multiple packers between the stages.
While the above method is described as having two stages, one of skill in the art will appreciate that this could occur in a well having any number of stages and the loss of isolation could occur between any newly isolated stage and the prior stage.
Although the present invention has been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereupon without departing from the principle and scope of the invention. Accordingly, the scope of the present invention should be determined by the following claims and their appropriate legal equivalents.
There various elements described can be used in combination with all other elements described here unless otherwise indicated.
The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.
Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.
Ranges may be expressed here as from about one particular value to about another particular value and are inclusive unless otherwise indicated. When such a range is expressed, it is to be understood that another embodiment is from the one particular value to the other particular value, along with all combinations within said range.
Throughout this application, where patents or publications are referenced, the disclosures of these references in their entireties are intended to be incorporated by reference into this application, in order to more fully describe the state of the art to which the invention pertains, except when these references contradict the statements made here.
As used here and in the appended claims, the words “comprise,” “has,” and “include” and all grammatical variations thereof are each intended to have an open, non-limiting meaning that does not exclude additional elements or steps.
