RU2263701C2 - Hydrocarbon-based drilling fluid - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention provides environmentally safe hydrocarbon-based drilling fluid suitable for use during boring and completion of oil and gas wells. Drilling fluid is characterized by required viscosity and structural properties within a wide water content range and, in particular, contains, wt %: castor oil 50.0-83.0, colophony calcium resinate (thickener) 4.0, calcium chloride 10.0, Neonol AF-9/12 (emulsifier) 0-0.3, organophilic bentonite 2.0-3.0, water 0-30.0, and penosoline (waterproofing agent) 0-20.

EFFECT: improved environmental condition.

2 cl, 2 tbl

Description

The invention relates to the drilling and completion of oil and gas wells.

In world practice, hydrocarbon-based solutions (CBR) are increasingly widespread during drilling and especially when completing wells. Two classes of CBM are known: anhydrous hydrocarbon fluids (lime-bitumen fluids and thickened oils) and hydrophobic-emulsion drilling fluids (GER) with a high content of the aqueous phase (see A.I. Bulatov, A.G. Avetisov. Drilling engineer reference in two volumes. M: Nedra, 1985, volume 1, p. 360; V.I. Tokunov, I. B. Kheyfets. Hydrophobic-emulsion drilling fluids. M .: Nedra, 1983 - analogues).

The main problem with the use of hydrocarbon-based drilling fluids (CBF) is their potential negative impact on the environment, especially in environmentally sensitive areas (marine areas, river floodplains). This problem is especially acute due to the tendency to toughen environmental requirements around the world.

The problem of reducing the toxicity of CBR was posed abroad at the end of the 70s of the XX century and its solution was associated with the use of hydrocarbon fluids under the common name “mineral oils”. However, the use of mineral oils did not completely solve the environmental safety problems of CBR. The biodegradability of solutions based on them did not exceed 5%, which did not allow removing restrictions on their discharge into the sea.

In this regard, the problem of creating biodegradable drilling fluids on a synthetic non-aqueous basis was put forward, which are an alternative to CBR and have all their advantages.

Known emulsion drilling fluid containing non-polluting castor oil, which is a direct emulsion system, the basis of this drilling fluid is a complex gel, biodegradable in aerobic and anaerobic conditions, containing a non-polar dispersion medium, a liquid polymer surfactant surfactant, acid form, dissolved or dispersed in the specified non-polar medium, an agent for neutralizing a polymeric surfactant containing from 0.2 to 5 water molecules per surfactant molecule, emuls torr and / or solid filler which is soluble or insoluble in the apolar medium.

The gel is used to prepare a water-based drilling fluid (see US Pat. No. 5858928 A, C 09 K 7/02, January 1, 1999 — PROTOTYPE).

The disadvantage of this technical solution is that the hydrophobic (non-polar) gel itself is not used as a flushing fluid (according to patent US 5858928 A, C 09 K 7/02), and the drilling fluid prepared from it is aqueous, i.e., based it contains from 97 to 99.09% water. Therefore, in spite of its high water-holding capacity F = 18-20 cm ^3/30 min API, the released moisture may hydrate and softening water sensitive rocks forming the walls of the wells, and also cause swelling process the clay skeleton portion, an oil reservoir, which leads to decrease in its productivity or complete blockage.

The technical result of the invention is the creation of an environmentally friendly hydrocarbon-based drilling fluid (CBF) with the required viscosity and structural parameters in a wide range of water content by using a new widely available hydrocarbon base.

A drilling fluid containing castor oil, an emulsifier, calcium chloride, bentonite and water contains organophilic bentonite, as an emulsifier - neonol AF-9/12 and additionally a thickener - calcium rosin resinate in the following ratio, wt.%:

Castor oil 50.0 - 83.0 rosin calcium resinate 4.0 calcium chloride 10.0 Neonol AF-9/12 0 - 0.3 organophilic bentonite 2.0 - 3.0 water 0 - 30.0

The drilling fluid may additionally contain a water repellent - penosoline 0 - 2.0 wt.%.

The combination of the claimed components in the claimed ratios ensures the production of such an inverse emulsion, which when drilling, filtering into rocks, does not cause their swelling and, as a result, their softening. And when opening the oil and gas reservoir of the claimed drilling fluid does not cause swelling of the clay part of its skeleton, which ensures complete preservation of the reservoir properties of the reservoir.

In the course of laboratory studies, CBR samples of both classes were prepared — a solution that did not contain an aqueous phase and hydrophobic-emulsion drilling fluids (GER) with a minimum (10%) and 30% aqueous phase content.

CBM samples were prepared according to the methods and techniques described in the works “Hydrophobic-Emulsion Drilling Fluids”, V.I. Tokunov, I. B. Kheifits. - M .: Nedra, 1983, “The use of reverse emulsions in oil production”, G.A. Orlov, M.Sh. Kendis, V.M. Glushchenko. - M .: Nedra, 1991

In the research, methods and apparatuses were used in accordance with RD 39-2-645-81 “Method for monitoring the parameters of drilling fluids”, Krasnodar: VNIIKRneft, 1981

The results of studies of hydrocarbon-based solutions (CBR) for the proposed technical solution are presented in tables 1 and 2.

Table 1 Castor oil based CBF formulations Name of components Brand, grade, TU, GOST The content of components, wt.% Thickened Castor Oil GER-1 GER-2 Castor oil Commercial 83.0 73.7 50,0 Thickener. Rosin Calcium Resinate Environmentally friendly 4.0 4.0 4.0 Calcium chloride GOST 540-77 10.0 10.0 10.0 Neonol AF-9/12 (emulsifier) TU 38.507-635-171-91 - 0.3 0.2 Penozolin (water repellent) OP - - 2.0 Water technical - 10 30,0 Organophilic Bentonite TU 95-27-52-2000 3.0 3.0 2.0

The specified technical result is achieved at any value from the specified interval, for example, the drilling fluid contains in wt.%: Castor oil 80, calcium rosin resinate 4.0, calcium chloride 10.0, neonol AF-9/12 0.1, organophilic bentonite 2.5, water 3.3, penozolin 0.1 or castor oil 60, calcium rosin resinate 4.0, calcium chloride 10.0, neonol AF-9/12 0.25, organophilic bentonite 2, water 23.6, penozolin 0.15.

table 2 Castor Oil-Based Drilling Fluids (CBR) Property metrics unit of measurement CBR classes Thickened Castor Oil GER-1 GER-2 Density (ρ) g / cm ³ 0,997 0.886 1,04 Effective viscosity (η _eff. ) MPa · s 70 64 101 Plastic viscosity (η _square ) MPa · s 68 55 81 Dynamic shear stress (τ ₀ ) dpa 19.2 57.6 196 Static Shear Stress (SNA)
after 1 min of rest after 10 min of rest


dpa


one


one


3 dpa 2 1 6 The rate of filtration (f ₂₀ ) cm ^3/30 min 5,4 1,1 0 Clay capacity % 22.5 22.5 22.5 Sustainability hours not limited not limited > 340 Electrical stability (E) In (volt) 951 375 211 The rate of filtration (f ₉₀ ) cm ^3/30 min 15.97 19.17 1.27 Inhibitory ability (P ₀ ) cm / hour 0.187 0.187 0.187 The surface tension (σ) of the filtrate μN / m 7.80 7.82 6.52 Thermal stability ° C > 120 120 120

According to the experimental data given in tables 1 and 2, castor oil-based solutions (CBR) have technological parameters that meet all the requirements of drilling operations. Their rheological characteristics are quite low. Thus, the effective viscosity (see Table 2) for all three types of solutions is in the range of 60-70 mPa · s, which corresponds to the viscosity values of practically used oil-based solutions. Values of plastic viscosity in the range of 68-50 mPas, in solutions based on castor oil, are almost identical to the values of solutions based on oil. The dynamic shear stress in the range of 19-20 dPa for the proposed solutions is consistent with the values of the classic oil-based CBR and provides them with reliable endurance. The hot filtration index (Ф ₉₀ ) in the range of 1.27-19.17 cm ³ in 30 minutes allows solutions in castor oil to have low losses of the solution during circulation in the downhole conditions and corresponds in value to the classic CBR values. As for such indicators (for the proposed solutions), such as clay capacity, stability, electrical stability, their values characterize the proposed liquids as extremely stable (see table 2). Thermal stability of the proposed systems corresponds to 120 ° C.

It should also be noted as positive qualities that their high inhibitory ability (P ₀ = 0.187 cm / h) and the low surface tension of their filtrates (σ = 6.52-7.82 μN / m), which determines the high-quality opening of productive formations and high production rates raw materials.

In addition, the proposed castor oil-based drilling fluids are absolutely environmentally friendly and can be used for drilling offshore oil and gas deposits, as they allow the discharge of spent drilling fluids directly into the water without harming nature. After all, the base (castor oil) and the thickener are biodegradable and are completely utilized by microorganisms from the environment.

Thus, the task of the present invention is solved by thickening castor oil with calcium rosin resinate and creating invert (reverse) emulsions based on it.

Claims (2)

1. A drilling fluid containing castor oil, an emulsifier, calcium chloride, bentonite and water, characterized in that it contains organophilic bentonite, as an emulsifier - neonol AF-9/12 and an additional thickener - calcium rosin rubber in the following ratio of components, wt .%: Castor oil 50.0 - 83.0 Rosin Calcium Resinate 4.0 Calcium chloride 10.0 Neonol AF-9/12 0 - 0.3 Organophilic Bentonite 2.0 - 3.0 Water 0 - 30.0 2. The drilling fluid according to claim 1, characterized in that it further comprises a water-repellent penozolin - 0 - 2.0 wt.%.