RU2277572C1 - High-mineralization clayless drilling mud - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention relates to high-mineralization clayless drilling muds to expose producing reservoirs as well as when boring clays with tendency for softening during boring with aqueous drilling fluids and during making holes in salt-bearing formations. Drilling mud containing sodium format (9-30%) as stabilizer and weighting substance, marble powder (0-12%), and water contains sulfacell as regulator of rheological and fluid loss properties. Drilling mud may further comprise foam suppressor MAS 200 dissolved in diesel fuel at ratio 1:20 and in amount 0.2-0.4%.

EFFECT: enhanced flocculation properties of drilling mud to remove sludge during cleaning operation.

2 cl, 1 tbl

Description

The invention relates to the oil and gas industry, in particular to highly mineralized clay-free drilling fluids for opening productive reservoirs, as well as when drilling clay, prone to softening when drilling with water-based solutions and when drilling wells in saline formations.

Known clay-free drilling fluid system "Flo-Pro" / company MI Drilling Fluids /, including wt.%, As a stabilizer - magnesium oxide - 0.4, a regulator of rheological properties - Biopolymer Flo-Vis Plus - 0.5, modified starch Flo -Trol - 1.2, liquid bactericide MI Cide - 0.05, filler - marble powder - 9.0, weighting agent-potassium chloride - 3.0, water - the rest.

However, when drilling wells in carbonate rocks, this solution is unsatisfactorily cleaned of drill cuttings, which leads to rapid abrasive wear of both bottomhole and drilling equipment on the surface, and this solution is chemically aggressive with respect to equipment and environmentally hazardous to the environment.

The closest analogue is the technological fluid for drilling, completion and overhaul of oil and gas wells in the conditions of high pressure and high temperatures, including a polysaccharide reagent or a mixture of polysaccharide reagents, wt.%: 0.1 - 7.0, as a weighting agent - formic salt alkaline metal acids 45.0 - 83, 0 and the rest water (patent RU 2215016 C1, 09 K 7/02, 10.27.2003).

Known process fluid does not provide the required flocculating properties of the solution.

The task to which the claimed technical solution is directed is to create a drilling fluid to preserve the initial reservoir properties of the reservoir, to keep the rock mass, both sandstone and clay, from decompression, to ensure the properties of the solution for high-quality removal of drill cuttings from the bottom, to ensure high mechanical drilling speeds and increased durability of downhole equipment.

The technical result is the provision of high flocculating properties of the solution to remove sludge during cleaning.

Highly mineralized clay-free drilling fluid, including sodium formate, marble powder and water as a stabilizer and weighting agent, contains sulfacelles as a regulator of the rheological and filtration properties of the following ratio, wt.%: Sodium formate 9-30, sulfacell 2-3, marble powder 0-12, the rest is water. Highly mineralized clay-free drilling fluid may additionally contain as an antifoam MAC 200, dissolved in diesel fuel in a ratio of 1:20, in an amount of 0.2-0.4 wt.% By weight of the drilling fluid.

The causal relationship between the essential features and the technical result achieved is as follows: sulfacell gives the solution the necessary rheological properties and regulates water loss, and with the addition of sodium formate, these properties can change, so the concentration of sulfacell 2-3% can be considered optimal. With an increase in the concentration of sodium formate, the thixotropic properties are enhanced and the resulting solution is better cleaned of the cuttings, while the resulting effect exists up to a concentration of sodium formate of 30%. At the same time, introducing the antifoam MAC 200, dissolved in diesel fuel in a ratio of 1:20, it is possible to regulate the foaming process, where the optimal effect is achieved at a concentration of 0.2-0.4%.

The composition of the solution includes sodium formate (TU U 3.50-14308351-13 0-99), mass fraction 88%, mass fraction of water 0.66%. Known as a good plasticizer and preservative, it is used in construction and other sectors of the economy. The solution also contains sulfacell (TU 6-55221-1473-97), manufacturer of Special Burmaterials, Moscow, antifoam MAC 200 (TU 39-08-125-77), which is a highly dispersed fumed hydrophobized silica, manufacturer of Special Burmaterial, Moscow. The solution also includes marble, for example, grade MP-2 (ground micromarble TU 5716-002-369-45182-2003).

The solution is prepared as follows.

Industrial water is collected at the required volume of highly mineralized clay-free drilling fluid. Through the clay mixer, in a cycle, not through a well, up to 3% sulfacell is introduced. In the technical / casing / string, the fluid is replaced with the prepared solution. 9% sodium formate is injected through the well, bringing to the required density a highly mineralized clay-free drilling fluid, while sodium formate is saturated to 30%, and the density increases to 1210 kg / m ³ . If necessary, when opening permeable rocks, up to 12% of marble powder is added, the density increases to 1300 kg / m ³ . The thickness of the filter cake can be controlled by the selection of marble powder with different degrees of dispersion. During preparation, standard solution parameters are measured, for example, such as: density, conditional viscosity, dynamic shear stresses, plastic viscosity, static shear stress, fluid loss, pH of the medium, filter cake thickness, stickiness, etc.

In accordance with the above example, various versions of the solution were prepared, differing in the quantitative content of the ingredients.

The composition and properties of these solutions are shown in the table.

The tests performed show that changing the content of ingredients down (composition No. 1) does not provide the necessary technological parameters, and upward (composition No. 10) is not economically profitable, since the increased consumption of reagents does not lead to the expected effect, and at a formate concentration Sodium 31% properties provided by the action of sulfacell completely cease.

Table Example The composition of the solution, wt.% Density
Kg / m ³ Conditional
viscosity, sec Plastic
viscosity,
MPa · s CSN
dpa Water loss
cm ^3/30 min Sodium formate Sulfacell Marble
MP-2 powder Antifoam agent
MAC 200 Water one 0 3 0 0 97 1000 n / t - - - 2 9.0 3 0 0 88 - n / t - - - 3 16,0 2,4 0 0 81.6 1100 80 30.5 162.8 7 four 23.0 2,3 0 0 74.7 1140 90 33 153.3 - 5 28.0 2.1 0 0.2 69.7 1170 60 26 110,2 5.8 6 30,4 2.0 0 0.2 67.4 1210 65 26 71.84 6 7 28.5 2.0 6 0.3 63.3 1250 - 63 234 1,6 8 27.0 1.8 12 0.3 58.9 1295-1300 120 75 240 1.4 9 27.0 2,4 12 0.4 58.2 1300 125 - - - 10 28.0 2.2 fourteen 0.4 55,4 1320 fifteen - - -

Claims (2)

1. Highly mineralized clay-free drilling fluid, including sodium formate, marble powder and water as stabilizer and weighting agent, characterized in that it contains sulfacelles as a regulator of the rheological and filtration properties in the following ratio, wt.%: Sodium formate 9-30 Sulfacell 2-3 Marble powder 0-12 Water Rest 2. The solution according to claim 1, characterized in that it additionally contains as an antifoam MAC 200, dissolved in diesel fuel in a ratio of 1:20, in an amount of 0.2-0.4 wt.% By weight of the drilling fluid.