Description of the Prior Art [0002] Numerous organic and inorganic components are known for use as additives in drilling operations, both in aqueous fluids and oil muds, to control detrimental losses such as gross loss of whole fluid, commonly referred to as lost circulation.

Similarly, additives are used to control fluid loss and provide seepage control.

Organics are often preferred for their cost effectiveness as well as functionality.

Organics suffer from a drawback that they interfere with electrical stability of the drilling fluids and therefore affect readings for electrical stability when measuring for hydrocarbons.

[0003] Generally voltage applied across two electrodes is increased until the drilling fluid emulsion breaks and a surge of current flows between the two electrodes. The voltage required to break the emulsion is a common measure of the stability of such an emulsion. Oil-based muds are used where the use of water-based muds cannot solve specific problems, such as: drilling shales which swell or slough; drilling directional holes ; drilling hot, deep holes ; or to prevent or recover stuck pipe and the like. For proper functioning of oil-based muds, the small quantities of water used in oil muds must be completely emulsified in the oil. Electrical Stability or voltage break-down (V-B) is measured for oil muds to determine the stability of the emulsion.

Electrical stability measures the amount of current required to achieve the breakdown voltage or the point at which the emulsion becomes conductive. Pure oils do not conduct electricity whereas water is a highly effective conductor of electricity. High readings indicate stable, oil continuous emulsions, while low readings indicate poor

emulsions."E. S. ", or electrical stability of the emulsion, is measured by the test described in Composition and Properties of Drilling and Completion Fluids, 5th Edition, H. C. H. Darley, George R. Gray, Gulf Publishing Company, 1988, pp. 116, the contents of which are hereby incorporated by reference. Generally, the higher the number, the more stable the emulsion.

[0004] Efforts have been continuous in attempting to address the problem of lost circulation, seepage, or fluid loss. Patent literature has examples of various agricultural and cellulosic waste products being used as lost circulation materials and seepage control agents designed to function in specific ways. Yet lost circulation remains a critical issue in the drilling industry often directly affecting the profitability of a well.

[0005] Examples of patents addressing this recognized problem of lost circulation, seepage or fluid loss include US Patent 5,071, 575 and 5,004, 553 issued to House for well working compositions using ground oat hulls in a certain particle size range with the possibility of adding one or more agricultural byproducts including ground citrus pulp. Many patents teach the use of specific organic materials. U. S. Patent 5,147, 852 issued to Cowan, discusses the use of organic materials, specifically cellulose materials, generally described as those from wood sources of fibrous materials, indicating generally the benefit of cellulose. For example U. S. Patent No. 5,229, 018 issued to Forest teaches the use of peanut hulls as an additive along with a suitable suspending agent. However, organic additives added to drilling fluids generally suffer from certain drawbacks, in particular, interference with the electrical stability of oil-based drilling fluid.

[0006] US Patent No. 6,399, 545 recently issued to the current inventor, Rose, explores the use of fruit pomace in drilling fluid additives for the purpose of inhibiting lost circulation, seepage and/or fluid loss. However, the difficulty in use of various organic matters relative to the electrical stability has not previously been explored.

[0007] Common additives tend to drastically alter the properties of the drilling fluid.

One of the most difficult issues to address is the issue that organic additives tend to disrupt electrical stability and the ability to accurately measure hydrocarbon content.

This creates difficulties with the ability to determine producing formation locations

accurately. It would be advantageous to provide an additive such that an electrical well-logging tool when disposed in the drilling fluid with additive can accurately perform an electrical well-logging survey or imaging of a borehole containing the fluid with additive.

[0008] It would be advantageous to provide an additive that functions to prevent fluid loss, seepage and lost circulation while at the same time minimizing disruption of the electrical stability of the system. It would also be advantageous to create a method for producing such an additive. Furthermore, the use of organic waste products would allow for the advantage of a cost effective additive.

[0009] The use of an organic additive that otherwise reduces the need to add further refined chemical components to the system, such as lignosulfonates and tannins, would be advantageous.

[0010] The introduction of an additive that can be used in both water base and oil base well working fluids would be advantageous. An additive that provides the desired control without interfering with the rheology or the electrical stability of the system would also be advantageous.

[0011] The current invention includes certain advantages that will be appreciated by one skilled in the art as the description thereof proceeds.

BRIEF SUMMARY OF THE INVENTION [0012] The current invention advantageously presents an additive, and the method of use of such additive, for use in drilling fluid that does not substantially affect the electrical stability of the drilling fluid. The additive of the invention is useful in drilling fluid for drilling operation. The additive has the property of inhibiting seepage, lost circulation, and/or fluid loss and is useful for this purpose. Also, the additive of the invention includes an amount of fruit pomace such that the additive exhibits certain novel characteristics when added to the drilling fluid. The fruit pomace is ground to create granules, the granules being sieved to define an original size distribution. The amount of fruit pomace in the additive is such that the additive, when added to the drilling fluid in a quantity sufficient to inhibit seepage, lost circulation, and/or fluid loss, is effective to maintain the electric stability of the

drilling fluid. This ability to maintain the electric stability is exhibited by no or little change of the electric stability experienced upon addition of the additive. Any change experienced as a result of the addition of the additive is within a predefined range, the predefined range being effective such that an electrostatic measure for hydrocarbon content can be performed within a predetermined degree of error.

[0013] Preferred sources of fruit pomace include grape pomace, tomato pomace, beet pomace and the like. This pomace is then ground. A preferred embodiment also includes allowing the pomace to dry or acquiring dried pomace for grinding. After grinding the pomace into granules, the granules are sieved.

[0014] The additive of the invention is advantageously useful in all types of drilling fluids including oil mud, synthetic muds and aqueous muds.

[0015] In a preferred embodiment, the amount of fruit pomace included in the additive is at least 30% by weight fruit pomace to gain the advantage of maintaining the electrical stability within a predefined range. More preferably, the amount of fruit pomace included in the additive is at least 40% by weight fruit pomace. In one embodiment, the additive of the invention can include substantially only one fluid loss, lost circulation and/or seepage control agent. In that case, the sole fluid loss, lost circulation and/or seepage control agent is fruit pomace. Depending upon the particular application, it can be desirable to add wetting agents, fungicides, biocides, or rheological agents to the additive. Another preferred embodiment includes an additive containing at least 98% by weight fruit pomace. Furthermore, in a preferred embodiment, the additive includes only one fruit pomace, such as only tomato or only grape pomace.

[0016] The additive of the invention, when not substantially all fruit pomace, can contain other materials that are effective to inhibit seepage, lost circulation, and/or fluid loss. Inorganic materials are preferred, the inorganic material being ground to define an original inorganic size distribution.

[0017] The current invention includes mixing the pomace with organics to produce different blends that enhance the organics while maintaining electrical stability. Solid particles of organics added to a drilling fluid system tend to interfere with electrical

charges. It has been observed that the addition of pomace in accordance with the invention counteracts this effect. This is regarded to be an enhancement to the performance of the organics.

[0018] The invention also includes a method of performing drilling operations wherein the drilling fluid is circulated in a well being drilled in the ground wherein the invention includes the steps of preparing additive for addition to the drilling fluid, adding the additive to the drilling fluid, and circulating the drilling fluid with additive in the well while drilling operations are being carried out. Preparing the additive includes grinding an amount of fruit pomace to form granules and adding the amount of fruit pomace to create the additive. The amount of fruit pomace added is effective to substantially maintain the electric stability of the drilling fluid when added to the drilling fluid. The electric stability is to be maintained within the predefined range, the predefined range being effective such that an electrostatic measure for hydrocarbon content can be performed. The additive is also effective to inhibit seepage, lost circulation and/or fluid loss and the like. The ground fruit pomace granules are sieved such that the granules define an original particle size distribution.

[0019] Another preferred embodiment of the additive includes an amount of a facilitator effective to facilitate the incorporation of the additive into the drilling fluid such that the additive containing fruit pomaces acts to begin mixing with the drilling fluid immediately upon introduction of the additive to the drilling fluid. In this manner, the additive is substantially completely incorporated into the drilling fluid prior to delivery of the drilling fluid with additive downhole.

[0020] The structure and method of the present invention as well as other features, advantages, benefits and objects thereof over other structures and methods known in the art can be better understood with reference to the detailed description which follows.

DETAILED DESCRIPTION OF THE INVENTION [0021] A pomace, such as tomato, grape or beet, is generally described as the crushed matter remaining of the pressed items. This can contain any combination of pulp, skin, seed or other naturally occurring substance in the pressed item. These organic products can be used individually or in combination with each other or other products.

[0022] In drilling operations, drilling fluid electrical stability of about 350 volts or less, preferably about 250 volts or less, allows use of an electric logging tool. A fluid is stable if the electrical stability is above about 400 volts in a weighted fluid, which is above 10 pounds per gallon weight. Electrical stability of an unweighted fluid, which is below 10 pounds per gallon, is typically considered stable at 200 volts and above.

The drilling fluid, prior to addition of the additive, is relatively non-conductive. This is true of both oil based drilling fluids and aqueous based drilling fluids or invert emulsions. The presence of certain organic additives can interfere with electrical stability, as measured by used in API RP 13 B-2.

[0023] While it is known in the industry to use organic products to reduce lost circulation, each organic product has its own set of characteristics that can be useful or disruptive to the drilling fluid system. Fruit pulp products, however, provide surprisingly efficient results over other organics and provide the unexpected benefit of maintaining electric stability, in contravention to expectations based on behavior of other organic additives. It is postulated that the unexpected efficacy results from naturally occurring compounds in fruit pomace. This results in increased efficacy.

[0024] Wetting agents such as NOVAWETTM, a product of M-I Drilling fluids, are useful to enhance the dispersion of the additive throughout the drilling fluid for particular drilling fluids..

[0025] The fruit pomace to be ground is typical a byproduct from other industries and thus can be economically obtained. In fact, they are frequently considered waste materials and therefore pose a waste disposal problem. After acquiring the fruit pomace, further drying and/or pressing can be performed prior to such grinding, depending on the moisture content of the pomace. Another preferred embodiment

includes heating the products for a length of time in order to sanitize the organic products, thus further reducing the possibility of undesirable biological activity when the additive is mixed with the drilling fluid.

[0026] After the organic products of the invention have been ground, they are added to the drilling fluid. There are various apparatuses and methods known in the art for adding materials to drilling fluid such that the material is incorporated into the fluid, all of which are useful in this invention. A preferred embodiment includes mixing the additive into the drilling fluid using a conventional jet-type hopper.

[0027] The additive is typically ground coarse, medium, fine or ultra fine, depending upon the particular usage. Coarse is generally that which will pass through a 4 mesh and retained on a 60 mesh. Medium is consider that which will pass through a 20 mesh and be retained on a 100 mesh. Fine is typically that which will pass through a 60 mesh and be retained on a 600 mesh. Ultra fine passes through meshes smaller than 600 mesh. There are general categories of definitions and include some overlapping sizes of mesh. A preferred embodiment of the current invention includes providing two to fifty lbs of additive per barrel of mud circulated.

[0028] Following are test results on electrical stability.

ELECTRICAL STABILITY COMPARISON TEST Sample Description : Sample A-Grape Pomace Regular Sample B-Grape Pomace Fine Sample C-ground corn cob Sample D-Ground almond hulls Test Procedure: A base mud formulation was prepared and the electrical stability measured. This is reported below. 25 ppb sample was added and mixed 10 minutes. Samples were then rolled 72 hours at 150° F. Samples were removed from oven and electrical stability measured while samples were still at 150° F. Samples were then cooled to room temperature and the electrical stability measured again. Samples were then mixed one minute on multimixer and the electrical stability measured again.

Base Mud: 235 mls synthetic base oil 50 mls 10.8 ppg CaC12 brine 6 ppb organoclay 5 ppb Lime 8 ppb Emulsifier 250 g Barite Results: E a. 2 H A-xßràpe 0 B*Gråpe-C ; 3mld" ; D-kond ;, _- :,. : i'Regul. ar °,,,.,. e ;.- ;, : ; ; B-d'' : D-A Hot Polled 590 550 134 353 Room Temp 647 560 165 411 X l : mzu. rnix 657 560 160 433

[0029] The additives and the method of their use are useful in drilling fluids that are oil muds, including diesel and synthetic oils. The additives and the method of their use are also useful in aqueous drilling fluids.

[0030] From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus and structure.

[0031] It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

[0032] Because many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth is to be interpreted as illustrative and not in a limiting sense. [0033] For example the additives of this invention for use with drilling fluids not only perform as control agents for seepage, lost circulation and lost fluid control with the novel benefit afforded by pomace, but they also act as a thinner. The use of these compounds for purposes of thinning is encompassed within this invention.