RU2492208C2 - Cation-inhibiting drilling mud - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: drilling mud contains, wt %: clay powder 5-8; polyelectrolyte VPK-402 7-15; water - balance.

EFFECT: increased inhibiting ability in respect to clays, reduced filtration parameter, higher salt and heat resistance.

2 cl, 3 tbl

Description

The invention relates to water-based drilling fluids and can find application in the drilling of oil and gas wells, mainly in the drilling of unstable clay rocks and the opening of productive formations.

Potassium chloride is known in the prior art, including water, clay powder, a stabilizer — a filter reducing agent (acrylic reagent or water-soluble cellulose ethers), a clay inhibitor (potassium chloride), a thinner — a viscosity reducing agent (lignosulfonate), a lubricating additive, and, if necessary, a weighting agent and additive to increase thermal stability (V. Ryabchenko. Management of drilling fluid properties. - M., Nedra, 1990, p. 218, Table 8.8).

A disadvantage of the known composition is multicomponent, low inhibitory ability with respect to clays, low salt and thermal stability.

The closest technical solution to the proposed drilling fluid is a drilling fluid comprising water, clay powder and clay stabilizer VPK-402 (described in RU 2148702 C1, E21B 33/13, C09K 7/02, 05/10/2000).

A disadvantage of the known composition is the low inhibitory ability with respect to clays, a high value of the filtration rate, low salt and heat resistance.

The technical result to which this invention is directed is to eliminate these drawbacks, namely, increasing the clay inhibitory ability, decreasing the filtration rate, and increasing the salt and thermal stability.

This technical result is achieved due to the fact that in a drilling fluid, including water and clay powder (for example, grade PBMB), as an inhibitor of clay, a decrease in filtration and to increase salt and thermal stability, VPK-402 polyelectrolyte is used, with the following ratio of components, masses .%:

Clay powder 5-8; VPK-402 7-15; Water rest.

In order to increase heat resistance while maintaining low values of the filtration index at a temperature of 130 ° C and a pressure of 3.5 MPa, hydrocarbons are introduced into the solution up to 10-15%.

To increase the density of the drilling fluid can be heavier barite concentrate.

In the proposed drilling fluid can be used bentonite clay powder grades PBMA, PBMB, PBMV, PBMG and PKGN, which is produced in accordance with TU 2164-004-0013836-2006 "Clay powder".

VPK-402 polyelectrolyte is a liquid with a uniform consistency without impurities from colorless to yellow. The molecular weight of the polymer is approximately 3 · 10 ⁵ . VPK-402 polyelectrolyte is a high molecular weight cationic polymer with a linear cyclic structure, obtained by radical polymerization of dimethyldiallylammonium chloride monomer, which, in turn, is made from allyl chloride and dimethylamine by heating in an alkaline medium.

VPK-402 polyelectrolyte is used in a cationic-inhibiting drilling fluid as a flocculant and coagulant. VPK-402 allows you to intensify the water treatment processes during the deposition of suspended particles of activated sludge and to ensure effective treatment of turbid waters.

The invention is illustrated in Tables 1, 2 and 3. Table 1 shows the results of studies on the effect of VPK-402 on the technological parameters of drilling fluids. Table 2 reflects the results of studies on the effect of VPK-402 on clay stability in comparison with the closest technical solution adopted as a prototype. Table 3 reflects the changes in filtration (F) at high temperatures.

From Tables 1 and 2 it follows that when the VPK-402 polyelectrolyte content is below 3%, the filtration rate increases (Table 1, Clause 4), and below 7% the stability of plastic and hydration-active clays is not ensured (Table 2, Clause 3) . It was experimentally obtained that the minimum permissible content of VPK-402 should be 7%. An increase in the VPK-402 content of more than 15% is inefficient (Table 1, Section 10, Table 2, Section 7), since it leads to an excessive consumption of VPK-402.

During drilling in clay deposits, the enrichment of the solution and the growth of rheological parameters such as plastic viscosity η _PL and dynamic shear stress τ ₀ occur (Table 1, paragraphs 2, 11). To reduce rheological parameters produce processing. So the additive VPK-402 in the form of a dilute aqueous solution (table 1, paragraphs 12, 13) allows you to restore rheological indicators.

Thus, from Tables 1 and 2 it follows that the use of VPK-402 in the indicated amounts allows one to lower the filtration indices, control the rheological properties and maintain the stability of clay rocks, that is, ensure the achievement of the indicated technical result — an increase in the clay inhibitory ability.

An increase in the density of the drilling fluid is made by the addition of barite in an amount of from 5 to 50%, and an increase in heat resistance is performed by introducing liquid hydrocarbons. With a decrease in hydrocarbons of less than 10% (Table 3, paragraphs 1, 2), the filtration rate increases, and with an increase in hydrocarbons of more than 15% (Table 3, paragraph 9), an overrun occurs with a slight change in the filtration index. The proposed drilling fluid is highly resistant to salt aggression: the addition of calcium and sodium chlorides practically does not affect the technological parameters of the system (Table 3, paragraphs 5, 8).

The proposed drilling fluid can be prepared as follows. First, water is mixed with clay powder before it is dissolved, then VPK-402 is added to the clay suspension, and, if necessary, a barite weighting agent and an additive to increase heat resistance.

Table 1 No. The composition of the solution, wt.% Solution indicators F, cm ³ at 25 ° C at 82 ° C η _pl , MPa · s τ ₀ , Pa η _pl , MPa · s τ ₀ , Pa Known solution (prototype) one 6% GR + 0.3% VPK-402 62 17 22 7 17.6 2 6% GR + 1% VPK-402 75 10 17.1 6 11.7 3 6% GR ++ 1% VPK-402 + 15% clay sludge Non-flowing solution Cationic Inhibiting Mud four 6% GR + 1.8% VPK-402 35 10 fourteen 8 9 5 6% GR + 3% VPK-402 eleven 12 4.9 10 1.9 6 6% GR + 5% VPK-402 7 twenty 5.7 fourteen 3.3 7 6% GR + 7% VPK-402 6 29th 7.3 17 4.4 8 6% GR + 10% VPK-402 four 35 7.3 21 5,4 9 6% GR + 15% VPK-402 3 48 8.3 28 6.8 10 6% GR + 20% VPK-402 3 64 23 32 fifteen eleven 6% GR + 10% VPK-402 + 15% clay sludge 3,5 57 16.5 16 12 12 6% GR + 10% VPK-402 + 15% clay mud + 5% aqueous VPK-402 in the form of a 5% concentration. four 39 11.8 28 8.6 13 6% GR + 10% VPK-402 + 15% clay mud + 10% aqueous VPK-402 in the form of a 5% concentration. four 32 6.4 eighteen 5.9 Note: 6% GR - 6% clay mortar from PBMB grade clay powder, VPK-402 - highly effective coagulant polyelectrolyte, Ф - filtration rate, η _pl - plastic viscosity and τ ₀ - dynamic shear stress.

table 2 No. Solution composition Behavior of clay samples aged in a solution medium for 1 day plastic hydration-active Known solution (prototype) one 6% GR + 0.3% VPK-402 swelling swelling and destruction 2 6% GR + 1% VPK-402 swelling swelling and destruction Cationic Inhibiting Mud 3 6% GR + 5% VPK-402 slight swelling swelling and destruction four 6% GR + 7% VPK-402 no swelling slight swelling and destruction 5 6% GR + 10% VPK-402 no swelling slight swelling and destruction 6 6% GR + 15% VPK-402 no swelling slight swelling and destruction 7 6% GR + 20% VPK-402 no swelling slight swelling and destruction

Table 3 No. Solution composition F, cm ³ at 130 ° C, P = 3.5 MPa one 6% GR + 12% VPK-402 32 2 6% GR + 12% VPK-402 + 5% liquid hydrocarbon 26 3 6% GR + 12% VPK-402 + 10% liquid hydrocarbon fourteen four 6% GR + 12% VPK-402 + 10% liquid hydrocarbon after temperature control for 12 hours at 130 ° fourteen 5 6% GR + 12% VPK-402 + 10% liquid hydrocarbon + 10% NaCl 12 6 6% GR + 12% VPK-402 + 15% liquid hydrocarbon 10,4 7 6% GR + 12% VPK-402 + 15% liquid hydrocarbon after temperature control for 12 hours at 130 ° C 9.2 8 6% GR + 12% VPK-402 + 15% liquid hydrocarbon + 5% CaCl ₂ 9.6 9 6% GR + 12% VPK-402 + 20% liquid hydrocarbon 7 10 6% GR + 15% VPK-402 + 10% liquid hydrocarbon fourteen

Claims (2)

1. Drilling fluid, including water and clay powder, containing as an inhibitor of clay, a filter reducing agent and a viscosity regulator VPK-402 polyelectrolyte, in the following ratio, wt.%:
Clay powder 5-8; VPK-402 7-15; Water Rest 2. The drilling fluid according to claim 1, characterized in that it contains hydrocarbons in an amount of from 10 to 15 wt.%.