FI67395C - BORRVAETSKETILLSATSER - Google Patents

Description

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Patent- oeh registeretyrelaen 'Awfllan uthyi odt «mtrift— peblicem» 30.11 .8 * 4 (3 ^ (33) (31) iypi *** r «« aeikeu * -enW Prterttet 05.05.78 usa (us) 903281 (71) Dresser Industries, Inc., Dresser Building, Elm and Akard Streets,

Dallas, Texas 75221, USA (72) Paul Henry Javora, Dr. Houston, Texas, Bethel Quinton Green, Houston,

Texas, USA (US) (7 * 0 Oy Koi ster Ab (5 **) Drilling Fluid Fillers - Borrvätsketi 11 satser This invention relates to drilling fluid additives for use in drilling for oil and gas wells.

Most commonly, aqueous dispersions of clay such as benthic rivet, illite, kaolinite or the like are used as drilling fluids. These dispersions often contain sodium hydroxide and a dispersant to form a freshwater-based liquid, lime and a dispersant to form a limestone-based liquid or calcium sulfate, sodium hydroxide and a dispersant to form a gypsum-type liquid. Seawater can be used as the liquid phase of the drilling fluid, and a seawater dispersion (seawater slurry) can be prepared from each of the above materials. Fine, high specific gravity and relatively inert minerals are often added to these drilling fluids to increase their specific gravity. Often, ground barite is used in the manufacture of high-weight drilling fluids, such as oils are often needed in drilling for gas sources to penetrate through the layers of soil to overcome the high pressures that occur when penetrating. The composition of the high-weight 67395 drilling fluid must be adjusted to relatively narrow limits in order to be able to perform drilling in deep, high-pressure sources without interference. High weight drilling fluids are expensive, and deep springs in which they are used are very expensive. For this reason, and because close control is required, better chemicals are needed in the manufacture and use of these fluids for drilling.

When using a rotary drill, the drilling fluid required must be of sufficiently high viscosity to easily transport the rock chips and other material removed by the drill to the surface with the fluid flow, and should be thixotropic so that at any time when drilling stops the fluid gels and prevents rock chips from settling.

The apparent viscosity of a drilling fluid, i.e. its relative non-flowability, depends on two properties, plastic viscosity and yield point. Each of these represents a different cause of non-drainage. Plastic viscosity is a property that depends on the concentration of solids in a liquid, while yield strength is a property that depends on the forces between particles. On the other hand, gel strength is a property that indicates thixotropy of a dispersion at rest. Dispersion (slurry) yield point, gel strength, and apparent viscosity are controlled by chemical treatment with materials such as complex phosphates, alkalis, excavated lignites, plant tannins, and modified lignosulfonates. Chromium-modified lignosulfonate as well as mixed metal lignosulfonate modified with chromium and iron have been found to be effective in controlling the viscosity of drilling fluids. However, it has been found that chromium compounds, especially those with a chromium value of 6, are toxic in nature. As a result, authorities around the world have regulated, or are in the process of regulating, strict controls on the use of chromium-containing compounds in oil and gas drilling for fear of polluting the environment. Although chromium is usually trivalent in lignosulfonate, its use has been severely restricted by some authorities.

U.S. Patent Nos. 2,935,473, 2,935,504, 3,037,923 and 3,168,511 disclose processes for the preparation and use of iron, chromium, aluminum and copper lignosulfonates and mixtures thereof as diluents and viscosity control additives in clay-based drilling fluids. They also disclose methods for oxidizing the lignin component of a lignosulfonate material, generally using lignin-containing broth from wood pulping as a starting material; these patents also disclose the benefits of using certain of the aforementioned cations in connection with such an oxidized lignosulfonate.

It has now been found that the lignosulfonate salts of zinrkcnium and its mixture with the iron salt, i. zirconium iron liqunosulfonate are excellent viscosity controlling additives in drilling fluids.

The present invention thus relates to a viscosity-controlling additive containing a water-soluble lignosulfonate salt, which is characterized in that the cation of the lignosulfonate sucl is zirconium, or zirconium and iron, to be added to the aqueous drilling fluid.

Commercially available zirconium compounds usually contain a small percentage of hafnium, and when reference is made in this application to zirconium and zirconium salts, it is meant not only pure zirconium salts but also those containing a conventional percentage of hafnium.

The additives according to the invention are in many cases more effective viscosity control agents than the chromium or chromium-iron lignosulfonates previously known and widely used in drilling fluids. They have the added advantage of being non-toxic, such as chromium lignosulfonates.

The lignosulfonate salts are preferably prepared by reacting the lignin broth obtained from wood pulping with the desired metal or metal salts and, if necessary, removing the precipitated material. If the material needs to be oxidized, oxidation can be performed at any stage of the process. If necessary, the product can be sulfonated to introduce additional sulfonate groups into the product.

Depending on the chemically complex nature of the sulfonated lignin material used in the preparation of the additives, the exact chemical composition of the additives has not been fully elucidated. Thus, when these compounds are referred to as "lignosulfonates", it is not limited to salts formed in a chemical base exchange reaction; they may also be chelates or other metal complexes.

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For example, U.S. Pat. No. 3,087,923 discloses that oxidation of sulfite waste liquor components obtained from wood pulping results in modified properties, such as reduced viscosity of the clay suspension and reduced gelation of such suspensions. For this reason, it is preferable to use conventional oxidants, such as hydrogen peroxide or ozone, or electrolytic oxidation in the treatment of the lignin broth and in the preparation of the compounds of the invention. These methods are described in detail in U.S. Patent No. 3,087,923.

Viscosity control agents prepared by the reaction between a lignosulfonate broth and a zirconium salt or complex have generally been found to be effective when the zirconium content of the product is 1-9% by weight, preferably 4-6% by weight. The use of higher amounts of zirconium does not appear to improve product viscosity control properties. When using zirconium iron materials, products with 1-3% by weight of iron and a total metal content (Fe + Zr) of 4-6% by weight are particularly effective. If the lignin component of the lignosulfonate is partially oxidized, it is preferably used in an amount of 1 to 5% by weight and most preferably 3 to 5% by weight.

In order that the subject of the invention may be better understood, the following examples are provided to illustrate this.

In these examples, all parametir, i. apparent viscosity, plastic viscosity, yield point, and gel strength were measured by standard methods described in API Recommended Practice 13B Standard Procedure for Testing Drilling Fluids, 6th Edition published by the American Petroleum Institute, April 1976. Parameters are expressed using the following units: apparent viscosity : centipoise (cps); plastic viscosity: centipoise (cps); yield point: lbs / 100 ft; 2 gel strength: lbs / ft. all percentages are by weight unless otherwise indicated.

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Example 1

A lignosulfonic acid solution was prepared from 834 g of hardwood sulfite broth (obtained from consolidated Papers, Inc., containing 55% solids and 2% Ca), 300 g of water, and 20 mL of concentrated sulfuric acid. The mixture was heated at 60 ° C for 3.5 hours, filtered to remove precipitated gypsum. The obtained lignosulfonic acid solution (351 g) was diluted with 100 g of water, to which was added 47 g of a zirconium acetate-acetic acid solution containing zirconium in an amount corresponding to 22% of zirconium dioxide. After a reaction time of 30 minutes, ferric sulfate hydrate containing 78.5% Fe 2 (SO 2) 2 was added to the solution. It was allowed to dissolve for several hours. The pH was then adjusted to 4.0 with 20% aqueous NaOH and the solution was spray dried to give a brown powdery material, zirconium iron lignosulfonate containing 4.9% zirconium and 1.5% iron.

The viscosity controlling and dispersing and / or deflocculating properties of this material were tested by adding it to a standard base drilling fluid made of clay material containing 25% sodium concrete (montmorillonite), 50% X-ACT clay (calcium montmorillite) and 25 % grun diet. In each experiment, zirconium iron lignosulfonate was compared to a stock slurry prepared by adding 170 g / L clay solids to water. Comparisons were made between a slurry to which no dispersant had been added and a slurry to which 15.0 g / l of cormilignosulfonate had been added and a slurry to which 15.0 g / l of zirconium iron lignosulfonate had been added. Each test slurry was aged for 18 hours at 93 ° C. The results are shown in Table I.

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Table I

Apparent Plastic Yield Limit Gel Strength Viscosity Viscosity * 1 min Ί U min

Basic substance 48 12 72 51 85

Chromium lignosulphonate 13 10 6 6 10 Z ironium iron lignosulphonate 13 12 2 38

From the above results, it can be seen that the thinning and dispersing properties of zirconium iron lignosulfonate are fully comparable to the corresponding properties of chromium lignosulfonates, although they do not contain chromium.

Example 2

A stirred solution of 50 g of water and 555 g of sulfite waste slurry of the same origin as in Example 1, but containing 57.5% solids and 2% calcium, was heated to 66 ° C and acidified with 27.5 g of concentrated sulfuric acid. The temperature was maintained above 66 ° C for 45 min, and then 97.5 g of a zirconium acetate-acetic acid solution corresponding to 22% zirconia was added to the solution. This mixture was stirred for 5 hours at a temperature above 66 ° C, then the precipitated gypsum was filtered off from the mixture. The pH of the filtrate was adjusted to 4.0 with 36.4 g of 50% sodium hydroxide. Spray drying gave a light brown zirconium lignosulfonate powder containing 5.0% zirconium.

Example 3

To the waste liquor used in Example 2, which contained 319 g of solid in 640 g of solution, was added 27.5 g of concentrated sulfuric acid. After 50 minutes, 98 g of a zirconium acetate-acetic acid solution containing 16 g of zirconium was added, and the mixture was stirred for 3 hours. Then 18.5 g of 30% hydrogen peroxide 7 67395 in 15 g of water were added, whereby the color of the solution darkened and the temperature rose to 38 ° C. The mixture was stirred for 2.5 hours, then filtered. The pH of the filtrate was adjusted to 4.0 with 38.3 g of 50% NaOH solution. Spray-drying the solution gave oxidized zirconium lignosulfonate containing 5.0% zirconium.

Example 4 To 555 g of the sulfite waste slurry used in Example 2 were added 70 g of water and 12.5 g of concentrated sulfuric acid. After 1 hour, 99 g of a zirconium acetate-acetic acid solution containing zirconium in an amount corresponding to 22% of zirconia was added, and the mixture was stirred for 2.5 hours. Upon addition of 18.5 g of 30% hydrogen peroxide in 15 g of water, the solution darkened and its temperature rose above 38 ° C. Within one hour, the temperature dropped to 35 ° C, to which was added 24.2 g of commercial grade ferrous sulfate hydrate containing 4.8 g of iron. After 2 hours, the mixture was filtered and the filtrate was neutralized to pH 4.0 with 29.3 g of 50% NaOH solution. Spray-drying the solution gave oxidized zirconium iron lignosulfonate containing 5.2% zirconium and 1.5% iron.