RU2330869C1 - Light weight drill fluid for opening-out of payout bed - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to drilling of oil and gas wells and can be used for opening-out of high permeability payout beds with normal and abnormally low bed pressure, and also for prevention and elimination of troubles at drilling of intake beds. A light weight drill fluid for opening-out of a payout bed contains, % mas.: carboxymethyl cellulose 1.0-1.2; stillage bottoms of synthetic fatty acids production with a number of a hydro carbcon chain C₁₆-C₂₃ and with an acid number of not less, than 100 1.0-2.0; alkali 0.5-0.7; a surface active substance 0.1-0.2; aluminosilicate micro spheres 5-20; water- the rest.

EFFECT: upgraded quality of opening-out of payout beds and prevention of drill fluid intake.

1 tbl, 1 ex

Description

The invention relates to the drilling of oil and gas wells and can be used for opening highly permeable reservoirs with normal and abnormally low reservoir pressures (ANPD), as well as for the prevention and elimination of complications when drilling absorbing reservoirs.

Known lightweight invert dispersion [1] containing hydrocarbon liquid, water, aluminosilicate microspheres and surfactants in the following ratio of components,% wt.: Hydrocarbon liquid 20-52; aluminosilicate microspheres 2-30; water is the rest.

The disadvantages of the known lightweight invert dispersion are environmental hazard and instability over time.

The closest technical solution to the claimed is a drilling fluid [2], containing,% wt .: polyacrylamide 0.1-03; carboxymethyl cellulose 0.1-0.3; Sprint reagent - a mixture of nonionic and anionic surfactants based on synthetic fatty acids 0.1-0.3; water is the rest.

The main disadvantages of the known drilling fluid are low structural and mechanical, insulating properties, high density and filtration, as a result of which the quality of opening of reservoirs is reduced, absorption and loss of the fluid are possible. The disadvantages of this solution are that, at elevated temperatures in the well, polyacrylamide is destroyed due to degradation, there is no co-formation, structure-forming dispersed phase in the solution, which allows the formation of an impenetrable insulating crust on the walls of the well, which limits the filtration of the dispersed medium into the formation.

The aim of the present invention is to improve the quality of the solution by reducing the filtration rate, increasing the structural, mechanical and waterproofing properties, forming a filter cake while maintaining a low density of the solution and a high recovery coefficient of the formation permeability.

The technical result of the invention is improving the quality of the opening of reservoirs, the prevention of absorption of the drilling fluid.

The goal and technical result are achieved by the fact that the well-known drilling fluid, including CMC carboxymethyl cellulose, an additive based on synthetic fatty acids FFA and water, additionally contains a surfactant surfactant and aluminosilicate microspheres, and bottoms as synthetic synthetic fatty acid additives the production of synthetic fatty acids with a hydrocarbon chain number of C ₁₆ -C ₂₃ and with an acid number of at least 100, washed away with alkali in the following ratio of components,% wt .:

CMC 1.0-1.2 Distillation residues of the production of FFA 1.0-2.0 Alkali 0.5-0.7 Surfactant 0.1-0.2 Aluminosilicate Microspheres 5-20 Water rest

From the patent and scientific and technical literature, we do not know drilling fluids containing a combination of the above ingredients in the proposed quantitative ratio, which allows us to conclude that the proposed solution is new.

A comparative analysis with the prototype allows us to conclude that the inventive drilling fluid differs from the known one in that the residual FFA during the reaction with NaOH form soap, which is a builder in the solution that forms the main rheological parameters. The resulting soap, having non-inogenic and anionic surface active properties, together with a surfactant hydrophobizes the surface of aluminosilicate microspheres, while maintaining an affinity for the dispersion medium - water. As a result, the surface of the microspheres is coated with surfactants and saponified FFA molecules, and the microspheres themselves remain in suspension in a highly viscous gel-like dispersion medium. In this case, the solution remains stable and does not stratify for a long time. FFA, surfactants and CMCs are resistant to elevated temperatures. In addition, saponified still bottoms SJK and surfactants hydrophobize the reservoir rock in the pore channels, which improves the quality of the opening of the reservoir.

In the developed solution, aluminosilicate microspheres reduce the density, increase the structural-mechanical and insulating properties of the solution, protect the formation from pollution and absorption.

Due to the mutual influence of saponified still bottoms of FFA, polymer and surfactant (i.e., synergistic effect) on microspheres, the claimed solution has satisfactory technological properties.

From the current level of technology, we do not know that the ingredients included in the proposed solution provide the above properties, which allows us to conclude that the claimed technical solution meets the criterion of "inventive step".

Domestic and imported CMCs with a polymerization degree of 600-900 and a degree of substitution of 80-85, polyanionic cellulose, starch, xanthan biopolymers can be used as a thickener for a dispersion medium and a fluid loss reducer.

As surfactants that improve the stability of the drilling fluid due to hydrophobization of the surface of the microspheres, Neftenol GF, Neonol BS-1, Sinol AN-1, IVV-1, OP-10 can be used.

Vat residues of FFA with the number of the hydrocarbon chain C ₁₆ -C ₂₃ and the acid number 120-150 are produced by Omsknefteorgsintez.

Aluminosilicate microspheres of the MS-400 brand are produced by Granula CJSC (Yekaterinburg).

The essence of the invention is illustrated by the following example (table, composition No. 5).

9.6 g of CMC were dissolved in 762 ml of fresh industrial water, heated to 50-55 ° C, and 16 g of still liquids of FFA were added. After complete dissolution of the bottoms of FFA, they were saponified by adding 11.7 ml of NaOH solution in the form of a 48% solution. 0.8 ml of surfactant and 40 g of MC-400 aluminosilicate microspheres were successively added to the washed solution and stirred for 1 hour to cool the solution to room temperature, as well as to uniformly distribute the MC-400 in the solution volume.

Similarly, other inventive drilling fluid formulations were prepared with different ratios of ingredients.

In vitro was investigated following compositions claimed solution and a solution of the prototype: the filtration rate of the filter-press FANN firm at a pressure drop of 0.7 MPa (F, ^cm3 / 30 min); plastic viscosity (η _PL , MPa ^s ); dynamic and static shear stress (τ and СНС _1/10 , dPa) on the FANN re-viscometer, density on the lever balance (d, kg / m ³ ).

The waterproofing properties and the permeability recovery coefficient were determined using a UIPK-1M filtration unit.

As the data shown in the table show, the claimed drilling fluid has low values of the filtration rate, density, high values of rheological parameters. The core permeability recovery coefficients are 98.3% (composition No. 5).

The claimed solution with such properties will provide better opening of productive formations and more effective prevention and elimination of complications.

Information sources

1. Patent No. 2176261, cl. С09К 7/02, 2001

2. RF patent, No. 1776264, cl. С09К 7/02, 1990

Table
The composition and properties of the claimed drilling fluid and mud prototype No pp The composition of the solution, wt.% Solution properties PAA CMC Cube rest SJK NaOH Reagent "Sprint" Surfactant MS-400 Water d, kg / m ³ F, ^cm3 / 30 min η _pl , MPa · s τ, dPa SNA _1/10 , dPa Prototype Solution one 0.3 0.3 - - 0.3 - - rest (99.1) 1002 14.0 2.0 6.0 0/0 Claimed solution 2 0.3 1,0 0.5 0.1 5 rest (93.1) 980 18.0 unstable 3 0.7 1,0 0.5 0.1 10 rest (87.7) 960 11.0 unstable four 1,0 2.0 0.7 0.1 10 rest (86.2) 960 6.0 25.0 96.0 16.6 / 23.8 5 1,2 2.0 0.7 0.1 5 rest (91.0) 980 5.2 24.0 200 48.8 / 63.4 6 1,2 2.0 0.7 0.2 fifteen rest (80.9) 945 4.8 25,4 209 49.2 / 64.3 7 1,2 2.0 0.7 0.2 twenty rest (75.9) 930 4.3 31,0 240 49.8 / 65.2 8 1,0 3.0 0.8 0.2 5 rest (90.0) 980 not fluid - - -

Claims (1)

Lightweight drilling mud for opening a reservoir containing CMC carboxymethyl cellulose, an additive based on synthetic fatty acids FFA and water, characterized in that the solution additionally contains a surfactant surfactant and aluminosilicate microspheres, and bottoms as a synthetic fatty acid additive production of synthetic fatty acids with a hydrocarbon chain number of C ₁₆ -C ₂₃ and with an acid number of at least 100, saponified with alkali in the following ratio of components, wt.%: CMC 1.0-1.2 Distillation residues of the production of FFA 1.0-2.0 Alkali 0.5-0.7 Surfactant 0.1-0.2 Aluminosilicate Microspheres 5-20 Water Rest