Date tree leaflet-based flaky lost circulation material

Abstract

A lost circulation material (LCM) having flakes formed from date tree leaflets is provided. The flakes of the date tree leaflet LCM may be formed by tearing and shredding date tree leaflets from date trees. The date tree leaflets may be obtained from date tree pruning performed by date tree farming industries. The date tree leaflet LCM may be added to o a drilling fluid to mitigate or prevent lost circulation in a well. Methods of lost circulation control with the date tree leaflets LCM are also provided.

Claims

1. A method to control lost circulation in a lost circulation zone in a wellbore, comprising: introducing an altered drilling fluid into the wellbore such that the altered drilling fluid contacts the lost circulation zone and reduces a rate of lost circulation into the lost circulation zone, where the altered drilling fluid consists of a drilling fluid and a lost circulation material (LCM), wherein the LCM consists of a plurality of processed date tree leaflets comprising a plurality of flakes, wherein each of the plurality of flakes has a length in the range of 5 millimeters (mm) to 8 mm, a width in the range of 3 millimeters (mm) to 5 mm, a thickness in the range of 0.05 millimeters (mm) to 0.15 mm, and an areal coverage in the range of 15 square millimeters (mm.sup.2) to about 40 mm.sup.2, wherein the plurality of processed date tree leaflets comprise a concentration of at least 10 pounds-per-barrel in the altered drilling fluid, wherein the drilling fluid consists of a bentonite mud, the bentonite mud comprising water, bentonite, caustic soda, and soda ash.

2. The method of claim 1, wherein the processed date tree leaflets comprise untreated date tree leaflets.

3. The method of claim 1, wherein the plurality of flakes are produced from shredded date tree leaflets.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a photograph of flakes formed from date tree leaflets in accordance with an embodiment of the disclosure.

(2) FIG. 2 is a photograph of a metallic screen for sealing and blocking efficiency tests in accordance with an embodiment of the disclosure;

(3) FIG. 3 is a photograph of a bentonite mud mixed with a date tree leaflet LCM in accordance with an embodiment of the disclosure.

(4) FIG. 4 is a photograph of a seal formed by the date tree leaflet LCM in a metallic screen after sealing and blocking efficiency tests in accordance with an embodiment of the disclosure.

(5) FIG. 5 is a block diagram of a process for manufacturing and using a date tree leaflet LCM in accordance with an embodiment of the disclosure.

DETAILED DESCRIPTION

(6) The present disclosure will now be described more fully with reference to the accompanying drawings, which illustrate embodiments of the disclosure. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

(7) As a wellbore is drilled, a drilling fluid is continuously pumped into the wellbore to clear and clean the wellbore and the filings. The drilling fluid is pumped from a mud pit into the wellbore and returns again to the surface. A lost circulation zone is encountered when the flow rate of the drilling fluid that returns to the surface is less than the flow rate of the drilling fluid pumped into the wellbore, and it is this reduction or absence of returning drilling fluid that is referred to as lost circulation.

(8) Embodiments of the disclosure include a date tree leaflet LCM that includes flakes formed from date tree leaflets to mitigate or prevent lost circulation in a well, as well as provide seepage control and minimize or prevent fluid loss. The flakes provide unified flow barriers to the loss of drilling fluid while drilling or the loss of cement slurry while cementing a well. In some embodiments, the flakes may have a generally rectangular shape. For example, For example, when introduced into a loss zone, the rectangular shapes of such flakes may create a carpet-like mat at the borehole wall to seal, block, and plug porous and permeable channels, fractures, cracks, figures, and vugs that may cause lost circulation.

(9) In some embodiments, the date tree leaflets LCM may include flakes formed from untreated date tree leaflets. As used in the disclosure, the term untreated or without treating refers to not treated with alkali or acid, not bleached, not chemically altered, not oxidized, and without any extraction or reaction process other than possibly drying of water. The term untreated or without treatments does not encompass tearing, grinding, cutting, or heating to remove moisture, but does encompass chemical or other processes that may change the characteristics or properties of the LCM. In accordance with this definition, an LCM that is treated may behave in a manner different than its original starting material. In such embodiments, the flakes formed from the date tree leaflets may be manufactured without treating before, during, or after separation, cleaning, or any other processing.

(10) FIG. 1 is a photograph 100 of flakes 102 formed from date tree leaflets. In some embodiments, the flakes may have a generally rectangular shape. In some embodiments, the flakes 102 may have a length in the range of about 5 millimeters (mm) to about 8 mm. In some embodiments, the flakes 102 may have a width in the range of about 3 mm to about 5 mm. In some embodiments, the flakes 102 may have a thickness in the range of about 0.05 mm to about 0.15 mm. In some embodiments, the areal coverage each flake may be in the range of about 15 mm.sup.2 to about 40 mm.sup.2. In embodiments, a date tree leaflet LCM having such flakes may mitigate or prevent lost circulation in a loss zone area ranging from 15 mm.sup.2 to about 40 mm.sup.2. Thus, the date tree leaflet LCM described in the disclosure may block or seal fractures having openings or channels close to the surface area coverage of the flakes formed from the date tree leaflets. Hence, the newly developed LCMs can seal and block more than one fracture widths of a potential loss zone to prevent the loss of whole mud while drilling or loss of cement slurry while cementing a wellbore.

(11) The date tree leaflets may be obtained from the pruning waste produced by date tree farming and date processing industries, resulting in a relatively large and sustainable source of leaflets for use in the date tree leaflet LCM described in the disclosure. Further, the biodegradable, non-toxic, and environmentally friendly properties of the date tree leaflet LCM may have superior environmental performance as compared to conventional flake LCMs. For example, the date tree leaflet LCM described in the disclosure may meet or exceed environment regulations for drilling and cementing operations as compared to cellophane flake LCMs or other artificial flake LCMs.

EXAMPLES

(12) The following examples are included to demonstrate embodiments of the disclosure. It should be appreciated by those of skill in the art that the techniques and compositions disclosed in the example which follows represents techniques and compositions discovered to function well in the practice of the disclosure, and thus can be considered to constitute modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or a similar result without departing from the spirit and scope of the disclosure

(13) The following non-limiting examples of a date tree leaflet LCM were prepared and evaluated against a commercially available LCM. Sealing and blocking efficiency tests were conducted on the date tree leaflet LCM and a commercially available LCM using a 250 micron porous metallic screen to simulate a high permeability loss zone. FIG. 2 is a photograph 200 of the 250 micron porous metallic screen 202 used to simulate a high permeability loss zone.

(14) The tests were conducted at conditions of ambient temperature and about 100 psi differential pressure. For the sealing and blocking efficiency tests, the date tree leaflet LCM and commercially available LCM were incorporated into a 65 pounds per cubic foot (pcf) bentonite mud. The composition of the 65 pcf bentonite mud with mud components expressed in pounds-per-barrels (lb/bbl or ppb) is shown in Table 1:

(15) TABLE-US-00001 TABLE 1 Composition of 65 pcf bentonite mud Mud Component Lb/bbl Water 330.67 Bentonite 25.00 Caustic Soda 0.25 Soda Ash 0.25

(16) The date tree leaflet LCM was tested at concentrations of 10 ppb in the 65 pcf bentonite mud and at 15 ppb in the 65 pcf bentonite mud. The 10 ppb solution was prepared by adding 10 grams of date tree leaflet LCM flakes to 350 cc of the 65 pcf bentonite mud. The 15 ppb solution was prepared by adding 15 grams of date tree leaflet LCM flakes to 350 cc of the 65 pcf bentonite mud. The 10 ppb and 15 ppb were added to the 65 pcf bentonite mud, mixed, and then tested using the 250 micron porous metallic screen to simulate a high permeability loss zone. FIG. 3 is a photograph 300 of the 65 pcf bentonite mud mixed with the date tree leaflet LCM (which may form or be referred to as a pill).

(17) The 65 pcf bentonite mud without the date tree leaflet LCM and the 65 pcf bentonite mud with 10 ppb and 15 ppb concentrations of the date tree leaflet LCM were tested using the following test procedure and an American Petroleum Institute (API) test apparatus having a test cell to contain the composition undergoing testing and the 250 micron porous metallic screen:

(18) 1. Prepare each composition;

(19) 2. Fill test cell of API test apparatus with a 350 cubic centimeter (cc) pill of the formulation;

(20) 3. Mount test cell to API test apparatus, affix the upper lid, and connect an air pressure line at about 100 psi pressure; and

(21) 4. Measure the total leak off over a testing time period.

(22) Table 2 shows the results of the sealing and blocking efficiency tests for the 65 bentonite mud without the date tree leaflet LCM and the date tree leaflet LCM at the 10 ppb and 15 ppb concentrations in the 65 pcf bentonite mud, with the total leak off measured in milliliters (ml) and the test duration measured in seconds (sec) or minutes (min):

(23) TABLE-US-00002 TABLE 2 Plugging Efficiency Test Results for 65 pcf bentonite mud and Date Tree Leaflet LCM Total Leak off Test Mud LCM Concentration (cc) Duration 65 pcf bentonite No LCM Based mud All mud 30 sec mud lost 65 pcf bentonite Date tree 10 ppb 18 ml 30 min mud leaflet LCM 65 pcf bentonite Date tree 15 ppb 18 ml 30 min mud leaflet LCM

(24) FIG. 4 is a photograph 400 showing a seal 402 in the 250 micron porous metallic screen 202 formed by the date tree leaflet LCM after the sealing and blocking efficiency tests. FIG. 4 depicts the carpet-like mat formed by the date tree leaflet LCM during the test conditions that seals, blocks, and plugs the 250 micron porous metallic screen 202. As shown in Table 2, the whole bentonite mud without the date tree leaflet LCM was lost immediately after (approximately 30 seconds) applying the 100 psi testing pressure. In contrast, as shown in Table 2, the 10 ppb concentration of the date tree leaflet LCM exhibited only 18 ml loss of whole mud after 30 minutes of applying the 100 psi testing pressure. Similarly, the 15 ppb concentration of the date tree leaflet LCM exhibited only 18 ml loss of whole mud after 30 minutes of applying the 100 psi testing pressure. Thus, at both the 10 ppb and 15 ppb concentrations, the date tree leaflet LCM in the 65 pcf bentonite mud exhibited negligible loses of whole mud and a large reduction in the rate of fluid loss. Consequently, at both the 10 ppb and 15 ppb concentrations, the date tree leaflet LCM demonstrated the formation of an effective flow barrier that prevented the loss of whole mud. Moreover, as shown in Table 2, the date tree leaflet LCM at 10 ppb concentration in the 65 pcf bentonite mud was a sufficient concentration to prevent of the loss of greater than a negligible amount of whole mud.

(25) The date tree leaflet LCM was also tested against a commercial flake LCM, Celloflake manufactured by Sodium Solutions, Inc. of Acheson, Alberta, Canada. The commercial flake LCM was tested at a concentration of 10 ppb/bbl in the 65 pcf bentonite mud. The 10 ppb solution was prepared by adding 10 grams of date tree leaflet LCM flakes to 350 cc of the 65 pcf bentonite mud. The date tree leaflet LCM was again tested at concentrations of 10 ppb/bbl in the 65 pcf bentonite mud and at 15 ppb/bbl in the 65 pcf bentonite mud, prepared in the manner previously discussed.

(26) The commercial flake LCM was added to the 65 pcf bentonite mud, mixed, and then tested using the 250 micron porous metallic screen to simulate a high permeability loss zone. The test was conducted using the test procedure and an American Petroleum Institute (API) test apparatus having a test cell, as described supra.

(27) TABLE-US-00003 TABLE 3 Plugging Efficiency Test Results for Date Tree Leaflet LCM and Commercial LCM Total Leak off Test Mud LCM Concentration (cc) Duration 65 pcf bentonite Date tree 10 ppb 18 ml 30 min mud leaflet LCM 65 pcf bentonite Celloflake 10 ppb 5 ml 30 min mud

(28) As shown in Table 3, the 10 ppb concentration of the Celloflake commercially available LCM exhibited 5 ml loss of whole mud after 30 minutes of applying the 100 psi testing pressure. Accordingly, as also shown in Table 3, both the date tree leaflet LCM and commercially available LCM (Celloflake) exhibited negligible loses of whole mud and a large reduction in the rate of fluid loss. Consequently, at 10 ppb concentration in the 65 pcf bentonite mud, the date tree leaflet LCM demonstrated comparable performance to the commercially available LCM. Thus, the date tree leaflet LCM may be a suitable alternative to commercially available flake LCMs.

(29) Date Tree Leaflet LCM Manufacture and Use

(30) In some embodiments, a date tree leaflet LCM may include flakes formed from processes date tree leaflets. The date tree leaflets may be produced as a waste by-product from date tree farming and date processing, and the date tree leaflets may be obtained from the pruning of date trees and date processing plants to provide sustainable source of material for the date tree leaflet LCM. Moreover, local sources of date tree leaflets may reduce the cost of imported LCM products, components, or both. In some embodiments, the date tree leaflets may be obtained from the species phoenix dactylifera. It should be appreciated that, in some embodiments, the date tree leaflets may be obtained from genetically modified date trees (that is, genetically modified organisms (GMOs)).

(31) In some embodiments, the date tree leaflet LCM may include flakes having a generally rectangular shape. In some embodiments, the date tree leaflet LCM may include flakes having a length in the range of about 5 mm to about 8 mm. In some embodiments, the date tree leaflet LCM may include flakes having a width in the range of about 3 mm to about 5 mm. In some embodiments, the date tree leaflet LCM may include flakes having a thickness in the range of about 0.05 mm to about 0.15 mm. In some embodiments, the date tree leaflet LCM may include flakes having an areal coverage in the range of about 15 mm.sup.2 to about 40 mm.sup.2, such that the flakes may mitigate or prevent lost circulation in a loss zone area ranging from 15 mm.sup.2 to about 40 mm.sup.2.

(32) In some embodiments, the date tree leaflets may include untreated date tree leaflets, thus preserving the environmentally-friendly and biodegradable properties of the manufacturing process, the leaflets, and the resulting LCM composition. For example, the flakes of the date tree leaflet LCM may be formed from untreated date tree leaflets. As used in the disclosure, the term untreated or without treating refers to not treated with alkali or acid, not bleached, not chemically altered, not oxidized, and without any extraction or reaction process other than possibly drying of water. The term untreated or without treatments does not encompass grinding or heating to remove moisture but does encompass chemical or other processes that may change the characteristics or properties of the leaflets and the flakes formed from the processed leaflets. In such embodiments, the date tree leaflets may be manufactured without treating before, during, or after drying or any other processing.

(33) In some embodiments, the date tree leaflet LCM may be added directly to a drilling fluid, such as a drilling mud, to create an altered drilling fluid having the date tree leaflet LCM. For example, in some embodiments, the date tree leaflet LCM may be added to (for example, blended with) an oil-based drilling mud or a water-based drilling mud. In some embodiments, the date tree leaflet LCM may be added at the mud pit of a mud system. After addition of the date tree leaflet LCM to a drilling fluid, the altered drilling fluid may be circulated at a pump rate effective to position the altered drilling fluid into contact with a lost circulation zone in a wellbore, such that the date tree leaflet LCM alters the lost circulation zone (for example, by entering and blocking porous and permeable paths, cracks, and fractures in a formation in the lost circulation zone, such as forming a plug in a fracture).

(34) In some embodiments, the date tree leaflet LCM may be used with one or more additional LCMs. For example, in such embodiments, one or more additional LCMs and the date tree leaflet LCM may be may be added directly to a drilling fluid, such as a drilling mud, simultaneously or in a specific order, to create one or more altered drilling fluids that may be circulated at a pump rate effective to position the altered drilling fluid into contact with a lost circulation zone in a wellbore.

(35) As noted in the disclosure, the eco-friendly, non-toxic, and environmentally friendly properties of the date tree leaflet LCM may minimize or prevent any environmental impact, any effect on ecosystems, habitats, population, crops, and plants surrounding the drilling site where the date tree leaflet LCM is used. Additionally, the date tree leaflet LCM may have comparable performance to cellophane flake LCMs or other artificial flake LCMs. Thus, date tree leaflet LCM may be used as a replacement LCM for cellophane flake LCMs or other artificial flake LCMs.

(36) FIG. 5 depicts a process 500 for manufacturing and using a date tree leaflet LCM in accordance with an embodiment of the disclosure. Initially, pruning waste from the pruning of date trees may be collected (block 502). The pruning waste may include date tree leaflets, date tree leaf stalks, and other date tree components removed during pruning of date trees. For example, date tree pruning may be performed at regular intervals (for example, yearly), resulting in a regular collection of date tree pruning waste. Dust may be removed from the pruning waste (block 504), such as by shaking and vibrating the pruning waste. In other embodiments, additional or alternative techniques may be used to remove dust from the pruning waste, such as blowing air over the pruning waste.

(37) Next, the date tree leaflets may be separated from the date tree leaf stalks and any other pruning waste (block 506). For example, in some embodiments, the leaflet may be separated by using a sharp edge cutter to move along the leaflet point attached to the leaf stalk. The separated leaflets may be torn lengthwise into strips (block 508). In some embodiments, the leaflet strips may have width in the range of about 3 mm to about 5 mm. In some embodiments, the leaflets may be torn manually using a fork-like tearing tool. In other embodiments, the leaflets may be torn automatically using a commercial industrial tearing tool having suitable speed, width, and size control capabilities (for example, a tool that enables the production of strips having a width in the range of about 3 mm to about 5 mm).

(38) The leaflet strips may then be shredded or otherwise processed into flakes (block 510). In some embodiments, the flakes have length of about 5 mm to about 8 mm. In some embodiments, the leaflet strips may be manually shredded. In other embodiments, the leaflet strips may be automatically shredded, cut, or otherwise processed using a commercial industrial shredded and cutting tool having suitable speed, width, and size control capabilities. As shown in some embodiments, the flakes may be packed (block 512). For example, the date tree leaflet flakes may be packed in paper bags containing about 25 kilograms (kg) of flakes. In some embodiments, a suitable amount of packed date tree leaflet flakes may then be transported to an oil and gas operations site for use as a date tree waste LCM.

(39) In some embodiments, the date tree leaflet LCM may be added directly to a drilling fluid (block 514), such as a drilling mud, to create an altered drilling fluid having the LCM. For example, in some embodiments, the date tree leaflet LCM may be added to (for example, blended with) an oil-based drilling mud or a water-based drilling mud. In some embodiments, the date tree leaflet LCM may be added at the mud pit of a mud system. After addition of the date tree leaflet LCM to a drilling fluid, the altered drilling fluid may be circulated at a pump rate effective to position the drilling fluid into contact with a lost circulation zone in a wellbore, such that the flakes of the date tree leaflet LCM alters the lost circulation zone (for example, by entering and blocking porous and permeable paths, cracks, and fractures in a formation in the lost circulation zone).

(40) In some embodiments, the date tree leaflet LCM and one or more additional LCMs may be added to a drilling fluid (block 516), such as a drilling mud, to create an altered drilling fluid having the LCMs. For example, in some embodiments, the date tree leaflet LCM and one or more additional LCMs may be added to an oil-based drilling mud or a water-based drilling mud. In other embodiments, the date tree leaflet LCM may be added to a cement slurry for use in a cementing operation.

(41) The biodegradation properties of the date tree leaflet LCM may enable the date tree leaflet LCM to easily degrade and disappear from the environment over time and minimize or prevent any environmental impact. Further, the non-toxic properties of the date tree leaflet LCM may minimize or prevent any effect on ecosystems, habitats, population, crops, and plants surrounding the drilling site where the date tree leaflet LCM is used.

(42) Ranges may be expressed in the disclosure as from about one particular value, to about another particular value, or both. 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, or both, along with all combinations within said range.

(43) Further modifications and alternative embodiments of various aspects of the disclosure will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the embodiments described in the disclosure. It is to be understood that the forms shown and described in the disclosure are to be taken as examples of embodiments. Elements and materials may be substituted for those illustrated and described in the disclosure, parts and processes may be reversed or omitted, and certain features may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description. Changes may be made in the elements described in the disclosure without departing from the spirit and scope of the disclosure as described in the following claims. Headings used described in the disclosure are for organizational purposes only and are not meant to be used to limit the scope of the description.