RU2601635C1 - Polymer-based drilling mud for well construction - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to drilling oil and gas wells, specifically to clayless biopolymer drilling mud, used for drilling producing reservoirs of horizontal wells and wells with large angle of deviation, represented by carbonate and terrigenous (sandstones) reservoirs, as well as for recovery wells by drilling sidetracking in different hydrogeological conditions. Polymer-based drilling mud for well construction contains, wt%: xanthane type biopolymer grade xanthan gum FCC IV 0.15-0.22; modified starch grade MK-F1 or MK-B 1.8-2.5; sodium carbonate and/or caustic soda 0.1-0.2; calcium carbonate 3-10; potassium chloride or potassium carbonate, sodium formate, or sodium chloride 3-23; surfactant OP-10 0.1-0.2; water - balance.

EFFECT: maintaining filtration-capacitance properties of productive reservoirs, reduction of reservoir energy consumption for movement of fluids using biodegradable polymers and easily removable sealants.

1 cl, 3 tbl, 1 ex

Description

The invention relates to the drilling of oil and gas wells, in particular to clayless biopolymer drilling fluids used to open productive formations of oil and gas wells represented by carbonate and terrigenous (sandstones) reservoirs, as well as to restore wells by drilling second trunks in various hydrogeological conditions.

A well-known drilling drilling fluid (patent of the Russian Federation No. 2289603 dated 04/10/2009) containing a polymer filter reducing agent — polyanionic cellulose or carboxymethyl cellulose, or carboxymethyloxyethyl cellulose, or hydroxyethyl cellulose, or hydrolyzed polyacrylonitrile ethylene fatty acid biopolymer — xanthan amide dianthide diamide concentrate, humates of alkali metals - carbon-alkaline reagent UCHR or humate-potassium reagent HCR, salts of alkaline and / or alkaline earth metals - KCl, NaCl, CaCl ₂ , MgCl ₂ , bisho fit 3.0-40.0, water in the following ratio of components, wt.%:

Specified Filter Reducer 0.1-1.0 Xanthan Biopolymer 0.2-0.5 Specified Fatty Ethylene Diamides 0.05-3.0 acids USR or GKR 3.0-6.0 Indicated Salts 3.0-40.0 Water rest

The disadvantages of the known drilling fluid are the use of polymer filtration reducers with high resistance to destruction, and its unsatisfactory structural and rheological properties, which leads to increased hydrodynamic resistance during circulation of the fluid in the well. As a result, increased repression appears on the productive reservoir, leading to an increase in the volume and depth of penetration of the solution filtrate into the reservoir. In addition, the use of calcium chloride increases the hardness of water, which leads to a decrease in the efficiency of the polymers.

The closest composition for the same purpose to the claimed invention in terms of features is a clay-free drilling fluid mainly for drilling horizontal wells and wells with a large deviation angle, including biopolymer, polyanionic cellulose, modified starch, alkali metal hydroxide, MIG surfactant, water-soluble salt silicic acid and water in the following ratio of ingredients, wt.%:

Biopolymer 0.05-0.2 Polyanionic cellulose 0.1-0.25 Modified Starch 1.15-2.0 Alkali metal hydroxide 0.045-0.16 Water Soluble Silicic Acid Salt 0.23-1.2 Surfactant MIG surfactant 0.3-1.0 Water rest,

while the mass ratio of alkali metal hydroxide and water-soluble salts of silicic acid is 1: 2.5-15.0, respectively. Additionally, in order to control the density, a weighting agent is allowed to be introduced into this solution — inorganic salts, or a carbonate weighting agent, or bentonite (RF patent No. 2186819 of 08/10/2002). This composition is taken as a prototype.

Signs of the prototype, coinciding with the features of the claimed invention is a xanthan type biopolymer, modified starch, calcium carbonate, an inhibitor of clay mineral swelling, a surfactant and water.

A disadvantage of the known composition adopted for the prototype is the presence of difficultly soluble components: polyanionic cellulose and bentonite. Polyanionic cellulose is a degradation resistant polymer, which complicates the displacement of drilling fluid filtrate from the formation into the well. In the case of using bentonite clay powder, a dense crust forms, which clogs the formation, which, on the one hand, reduces the filterability of the solution, and on the other hand, reduces the filtration characteristics of the reservoir due to the difficulty of decolmating clay particles, which will increase the cost of formation energy for the movement of fluids.

The objective of the invention is to obtain a biopolymer wash solution that preserves the filtration-capacitive properties of productive reservoirs and reduces the cost of reservoir energy for the movement of fluids using biodegradable polymers and easily removable colmatants.

The problem was solved due to the fact that the well-known polymer-based drilling fluid for well construction, containing xanthan type biopolymer, modified starch, clay mineral swelling inhibitor, calcium carbonate, surfactant and water, contains xanthan gum FCC xanthan type biopolymer IV, modified starch grade MK-F1 or MK-B, surfactant OP-10, as an inhibitor of clay mineral swelling, contains potassium chloride or potassium carbonate, or sodium formate tions, or sodium chloride, and further comprises soda and / or caustic soda, with the following ratio of ingredients, wt.%:

Xanthan gum FCC IV Biopolymer 0.15-0.22 Modified starch grade MK-F1 or MK-B 1.8-2.5 Soda ash and / or caustic soda 0.1-0.2 Calcium carbonate 3-10 Potassium chloride or potassium carbonate, or sodium formate, or 3-23 sodium chloride Surfactant OP-10 0.1-0.2 Water rest

Distinctive features of the proposed solution from the solution of the prototype - contains xanthan gum type biopolymer brand xanthan gum FCC IV, modified starch grade MK-F1 or MK-B, surfactant OP-10; as an inhibitor of clay mineral swelling, contains potassium chloride or potassium carbonate or sodium formate or sodium chloride; the introduction of soda ash and / or caustic soda; different quantitative ratio of the used ingredients wt. %: xanthan gum FCC IV biopolymer - 0.15-0.22; modified starch grade MK-F1 or MK-B - 1.8-2.5; calcined and / or caustic soda - 0.1-0.2; calcium carbonate - 3-10; potassium chloride or potassium carbonate or sodium formate or sodium chloride - 3-23; surfactant OP-10 - 0.1-0.2; water is the rest.

This technical result is achieved by using xanthan gum FCC IV brand xanthan as a regulator of structural and rheological parameters, as a pH regulator of calcined and / or caustic soda, as an inhibitor of the swelling of clay minerals of salt (potassium chloride, potassium carbonate, sodium formate, sodium chloride), as a filter starch reducing agent of the MK-F1 or MK-B brand, as a surfactant OP-10, as a weighting component and colmatant of calcium carbonate and s by selecting a certain quantitative ratio of components in the solution.

Xanthan gum FCC IV brand xanthan biopolymer is used as a structurant and filtration reducer. Xanthan molecules adsorb water with the formation of a three-dimensional network of xanthan double helix, similar in structure to the gel, but differing in lower viscosity, which allows to reduce filtration into the reservoir and to provide high solution endurance. The branched spatial structure of the xanthan polymer chain provides a reduction in the filtration of fluid into the reservoir. Xanthan forms toxitropic, thick non-Newtonian solutions. Its solutions exhibit the following properties: high viscosity at low concentration and shear rate; resistance to the influence of enzymes, salts, acids, bases; resistance to changes in ionic strength, temperature; constant high viscosity in a wide pH range from 2 to 12; high modulus of elasticity.

Xanthan biopolymer is a natural biopolymer, decomposes due to biodegradation in the reservoir and does not lead to its clogging. Its high pseudo-plasticity (with an increase in shear, the viscosity decreases sharply, after removing the force, the initial viscosity is restored almost instantly) helps to reduce the plastic and conditional viscosity of the drilling fluid.

Optimum conditions for the rapid "dissolving" and operation of the polymers are ensured with a pH value of 8-9. To this end, calcined and / or caustic soda is introduced into the washing solution. In addition to creating an alkaline environment, it effectively reduces the hardness of water, which improves the hydration of the polymer.

The use of starch grade MK-F1 or MK-B as a thickener and a water-retaining component will reduce the water loss of the solution without increasing its plastic viscosity. Modified extrusion starch effectively reduces the loss of water from the wash solution and is biodegradable, which ensures the natural decomposition of the polymer structure after a certain period of time. The biological decomposition of starch occurs in 2-7 days, depending on the pH of the medium, temperature and treatment of the solution with bactericides. This feature facilitates the displacement of the drilling fluid filtrate from the reservoir and contributes to the rapid restoration of reservoir productivity. Modified starch works successfully in both fresh and mineralized water. An important property of modified starch is its high resistance to mono- and polyvalent salt aggression. In addition, modified extrusion starch is an environmentally friendly, non-deficient and widespread reagent.

Calcium carbonate is used as a filler - weighting agent to increase the density of drilling fluids, and also as a colmatant - for clogging pores inside the rock arising on the inner surfaces of boreholes. Due to the ability to dissolve during hydrochloric acid treatments, the use of calcium carbonate will allow, without compromising the rheological properties of the solution, to improve the call flow from the well.

To ensure the necessary mineralization of the drilling fluid with low fluid loss, the following reagents are used to ensure proper mineralization of the drilling fluid:

- potassium chloride (KCl);

- sodium chloride (NaCl);

- sodium formate (HCOONa);

potassium carbonate (K ₂ CO ₃ ).

The use of the above salts allows you to create washing solutions with a density of 1050 kg / m ³ to 1550 kg / m ³ .

The developed drilling fluid has sufficiently high lubricating and hydrophobizing properties, which will prevent deep penetration of the filtrate of the drilling fluid into the formation and prevent the formation of persistent water-oil emulsions in the bottom-hole zone of the formation, as well as improve the working conditions of the bit at the bottom of the well and ensure free passage of the drilling tool along the trunk and will be preventative measures to prevent sticking of the drill string.

For the preparation of the inventive drilling fluid in laboratory conditions, the following substances were used:

- clay swelling inhibitor: potassium chloride according to GOST 4568-95 or potassium carbonate according to GOST 10690-73 or sodium formate according to TU 2432-011-00203803-98 or sodium chloride according to GOST 4233-77;

- filtration reducer: modified starch grade MK-F1 or MK-B according to TU 9187-002-00343094-2006;

- structurant: xanthan gum biopolymer of the brand xanthan gum (FCC IV), WEGO CHEMICAL & MINERAL CORP .;

- Kolmatant: calcium carbonate according to TU 95-2317-91;

- surfactant: OP-10 according to GOST 8433-81;

- medium pH regulator: calcined according to GOST 5100-85 and / or caustic soda according to GOST R 55064-2012;

- water.

The possibility of carrying out the claimed invention is confirmed by the following example.

Example.

To obtain the inventive drilling drilling fluid in 800 g of water (71.6%), 1.12 g of soda ash (0.1%) is introduced, 22.35 g of MK-F1 brand starch (2%), 2.23 g are gradually added. xanthan gum brand xanthan (FCC IV) (0.2%), 256.98 g sodium formate (23%), 33.52 g calcium carbonate (3%), 1.12 g OP-10 (0.1%) are mixed.

According to the described method, solutions were prepared with a different content of ingredients. The composition of the claimed and known drilling drilling fluids is shown in table 1. Data on the ingredient composition of the claimed drilling fluid are shown in table 2.

In the course of laboratory tests, the following parameters of the claimed drilling fluid were determined according to well-known methods: density, filtration rate, nominal viscosity, filter cake thickness, plastic viscosity, dynamic shear stress, static shear stress. Data on the properties of the claimed and known drilling fluids are shown in table 3.

As can be seen from table 1, the proposed drilling drilling fluid, in comparison with the analogue and prototype, does not contain difficultly soluble and resistant to degradation components, contains easily destructible components and effective inhibitors of clay swelling.

As can be seen from tables 1-3, the proposed drilling drilling fluids contain easily destructible components and have low values of the filtration rate and technologically necessary structural and rheological properties that are not inferior to the prototype, which allows you to maximize the permeability of the filter of productive reservoirs and reduce the cost of reservoir energy for the movement of fluids .

The developed polymer drilling drilling fluid is explosion-proof and fireproof, non-toxic and environmentally friendly.

Claims (1)

Polymer-based drilling fluid for well construction, containing xanthan type biopolymer, modified starch, clay mineral swelling inhibitor, calcium carbonate, surfactant and water, characterized in that it contains xanthan gum FCC IV brand xanthan biopolymer, modified brand starch MK-F1 or MK-B, surfactant OP-10, as an inhibitor of clay mineral swelling, contains potassium chloride or potassium carbonate, or sodium formate, or sodium chloride, and an additional but it contains soda and / or caustic soda, with the following ratio of ingredients, wt.%:
Xanthan gum FCC IV Biopolymer 0.15-0.22 Modified starch grade MK-F1 or MK-B 1.8-2.5 Soda ash and / or caustic soda 0.1-0.2 Calcium carbonate 3-10 Potassium chloride or potassium carbonate, or sodium formate, 3-23 or sodium chloride Surfactant OP-10 0.1-0.2 Water rest