RU2179567C2 - Polymeric hydrogel drilling mud - Google Patents

Abstract

FIELD: drilling and exploitation of oilwells and gasholes. SUBSTANCE: polymeric hydrogel drilling mud containing oxyethylcellulose, water-soluble trivalent metal acetate as a cross-linking agent, caustic soda and water has ferric (III) acetate complex prepared of: mas. p.: iron chloride, 1 and sodium acetate, 2 in the following ratio of component, wt.-%: oxyethylcellulose, 0.8-3.0; ferric (III) acetate complex, 1.5-4.5; water, 92.5-97.7; caustic soda above 100% to pH = 10-12. Invention can be used in drilling both in continental shelf and dry land and it corresponds to all requirements for drilling. EFFECT: preparing aqueous-based polymeric hydrogel drilling mud, improved ecological properties. 2 tbl, 2 ex

Description

 The invention relates to the field of drilling and operation of oil and gas wells and can be used when drilling on the continental shelf.

 There are a number of environmentally friendly emulsion drilling fluids based on synthetic fatty acid esters that meet environmental requirements for drilling and oil and gas production at sea and on land, and also reduce the cost of offshore drilling.

 The non-polluting drilling fluid developed by British Petroleum Development is known, which is an invert emulsion system based on a synthetic ester, biodegradable under aerobic and anaerobic conditions (see. New non-polluting drilling fluid, "Corrosion Protection and Protection environment. "1994, 10, pp. 32-33).

 The disadvantage of this solution is that it does not allow for logging and geophysical studies in order to determine the hydrocarbon reserves in the reservoir. In addition, it is flammable and explosive, since its hydrocarbon base is fatty acid esters capable of burning. In this regard, it has a lower cooling capacity than that of aqueous solutions, which dramatically reduces the time it takes to drill bits. According to published data (see description of the analogue), the cost of this solution is 75% higher than that of a water-based drilling fluid.

 Also known is a polymer-hydrogel drilling fluid containing hydroxyethyl cellulose, a structuring agent is a salt of a trivalent metal (chromic acetic acid), alkali and water of various degrees of mineralization (AS USSR 1724674, 09 K 7/02, 04/07/92 - prototype).

 The disadvantage of this solution is that it contains trivalent chromium, which is dangerous for biological objects, like a heavy metal, and therefore a serious environmental pollutant.

 The objective of the invention is the creation of polymer-hydrogel drilling fluid based on water, non-polluting and meeting all the requirements of drilling operations at sea and on land.

The essence of the invention lies in the fact that the polymer-hydrogel drilling fluid containing hydroxyethyl cellulose, the structurant is a water-soluble acetic acid salt of trivalent metal, caustic soda and water, as the structurant contains acetic acid complex of iron III, obtained from parts by weight of: iron chloride I and sodium acetate 2 , in the following ratio of components, wt.%:
Oxyethyl cellulose - 0.8 - 3.0
Acetic acid complex of iron III - 1.5 - 4.5
Water - 92.5 - 97.7
Caustic soda in excess of 100% - Up to pH 10-12
The acetic acid complex of iron III, which is a part of the polymer-hydrogel solution, is not acetic iron (since this does not exist in nature), but it is an organocomplex whose structure is poorly studied (see Remy. "Course of Organic Chemistry", Volume 2, in "Mir", M., 1974, p. 283).

 Polymer-hydrogel solution of the proposed composition exhibits a new property - environmental safety for the environment. The solution got its own name "ECORISH" (abbreviation for "environmentally friendly solution and sludge").

 When conducting toxicity studies of various drilling fluids at the Murmansk Marine Biological Institute (MMBI), the solution was presented under the code "ECORISH" and its composition was not disclosed (see DAN, 1998, vol. 361, 6, p. 851).

The following materials were used in the examples:
hydroxyethyl cellulose (OED) - TU 6-55-221 -1407-95 "Sulfacell"
iron chloride III - TU 6-00-129-91
sodium acetate - GOST 199-79
caustic soda - GOST 2263-79
acetic complex
iron III
The acetic acid complex of iron III is prepared by mixing 1 wt. including iron chloride III and 2 parts by weight sodium acetate. The product of their reaction has a bright red color, which indicates the formation of the necessary complex.

 The complex can be prepared both directly at the drilling site and in the factory.

 Environmentally friendly drilling fluid "ECORISH" is prepared as follows.

 Example 1. To 185 g of sea water with stirring, add 6 g of SEC brand Sulfacell and dispersed until the turbid suspension becomes a clear viscous solution of the SEC. Then, 9 g of the iron III acetic acid complex are introduced into the system. Further, after obtaining a homogeneous light brown viscous product, 1.75 ml of a 40% solution of caustic soda is added to it to pH 12 and the stirring speed is increased. Within 10 minutes, the system goes into a burgundy hydrogel with parameters, the values of which are presented in table 2 (experiment 1).

 Example 2. To 195.4 g of sea water, 1.6 g of OEC is added with stirring and dispersed until the cloudy suspension passes into a transparent viscous OEC solution. Then 3 g of acetic acid complex of iron III are introduced into the system. Further, after obtaining a homogeneous light brown viscous product, 1.5 mm of a 40% caustic soda solution is added to it to pH 10 and the mixing speed is increased. Within 10 minutes, the system goes into a burgundy hydrogel with parameters whose values are presented in table 2 (experiment 6).

Given in the table. 2 indicators of solutions were determined on standard instruments according to industry RD 39-2-645-81. Thus, the density was determined using a beam balance brand GRP-1, TU 25-04-2782-78, CHC _1/10 and rheological parameters - FAN rotational viscometer (model Fann -35SA, US production), filtering - the instrument HMW 6, pH - using the universal ionomer EV-74.

 The prepared ECORISH drilling mud that is environmentally compatible with the environment allows the use of carbonate, acid-soluble weighting agents: dolomite, chalk, marble chips and their mixtures in the amount to the required density, which provides high-quality opening and development of productive formations (the parameters of the dolomite-heavy mud are presented in Table. 2 (experiment 2).

 For drilling inclined and horizontal wellbores, the solution allows the introduction of lubricating additives such as FK-2000, TU 2458-001-26089145-95 rev. 1. The parameters of the solution containing 2.0% lubricant are given in table 2 (experiment 3).

 In order to enhance the inhibitory properties of the ECORISH solution, potassium chloride can be introduced into it. The parameters of the solution containing 3.0% KCl are given in table 2 (experiment 4).

An analysis of the experimental data given in Table 2 shows that the technological parameters of ECORISH fluids of different composition meet the requirements for clay-free drilling fluids (see Requirements for clay-free and low solids solutions, HX, 5, 1981, p. 26) So, based on the values of CHC _1/10 and τ ₀ , which in the given solutions are respectively in the range of 9-24 / 10-25 and 220-596 dPa, we can conclude that these solutions with a pseudoplastic nature of the flow have a high endurance ability.

 Indicators of filtration properties (F = 4.3-6.0) satisfy the requirements for trouble-free well drilling.

Low indicators of the thickness of the crust and the coefficient of friction (K = 0.1-0.5 mm; K _Tr = 0.04-0.19) allow these solutions to be successfully used for drilling deviated and horizontal wellbores.

 As for environmental safety, according to the results of the MMBI studies given in Table 1, “Comparative toxicity of drilling fluids and their components for littoral gammarids Gammarus oceanicus,” ECORISH drilling mud can (should) be used in search and assessment and industrial drilling in the seas of the continental shelf of Russia and coastal zones (see DAN, 1998, vol. 361, 6, p. 851).

The electrical resistivity (UES) of the environmentally friendly ECORISH solution is at least 0.5 Ohm • m (in downhole conditions) and 1.0-3.0 Ohm • m at 20 ^o C.

The use of this solution will allow:
- to keep clean and safe natural objects in places of drilling operations while reducing their cost;
- carry out logging and geophysical surveys in order to determine the volume of hydrocarbon reserves in the deposits, as well as work related to well drilling;
- completely eliminate the consumption of clay powder and fresh water, since the environmentally friendly solution "ECORISH" is prepared on sea and produced water;
- reduce the time spent on work related to the preparation and chemical treatment of the drilling fluid, which is due to the stability of the ECORISH mud indicators;
- improve the quality of the fastening of wells due to the absence of clay cake on the walls of the well;
- to improve the quality of the opening of productive formations due to the high inhibitory properties of the ECORISH solution;
- the use of environmentally friendly drilling fluid, does not require any additional capital investments.

 The total annual economic effect of the use of ECORISH solution consists of the annual saving effect in drilling, fixing and production of oil and gas, as well as due to its environmental safety, which allows discharging spent drilling fluid and drilling waste to the water area and other environmental objects of the continental shelf .

 As follows from Table 1, the recipes of Baker Hughes Inc. drilling fluids are favorably different, as well as the domestic Ecorish mud based on sulfacell (a reagent of ECC) and an organic iron salt, which did not cause the death of aquatic organisms, any food disturbances and reproductive behavior for 7 days at a concentration of 20-30 g / l. Obviously, only such drilling fluids should be used in prospecting, appraisal and industrial drilling in the seas of the Russian continental shelf and coastal zones.

Claims (1)

Polymer-hydrogel drilling fluid containing hydroxyethyl cellulose, a structuring agent is a water-soluble acetic acid salt of a trivalent metal, caustic soda and water, characterized in that the structure-forming agent contains an acetic acid complex of iron III, obtained from wt. including: iron chloride I and acetic acid sodium 2, in the following ratio, wt. %:
Oxyethyl cellulose - 0.8-3.0
Acetic acid complex of iron III - 1.5-4.5
Water - 92.5-97.7
Caustic soda in excess of 100% - up to pH 10-12

Images