SU1098951A1 - Drilling mud - Google Patents

Abstract

DRILLING SOLUTION, containing clay, water loss reducer, nitrilotrimethylphosphonic acid or 1-hydroxyethyllidene diphosphonic acid and water, characterized in that, in order to increase the inhibiting properties of the solution, it contains components in the following ratio, wt.%: Clay8-25 Water loss reducer 0% , 01-0.3 Nitrilotrimethylphosphonic acid or 1-hydroxyethylidene-diphosphonic acid 0.5-2.0 Water Still

Description

CO 00

coke

The invention relates to the drilling of oil and gas wells in sections composed of unstable clay rocks.

A necessary requirement for drilling in potentially unstable clay deposits is the use of inhibitors in drilling fluids, which reduce the swelling and dispersion of clays and thus ensure the stability of the wellbore.

Most commonly, gypsum, calcareous, high calcium and other drilling muds are used as inhibited, in which the dispersion of clay rocks is prevented by two or more valence cations, which are introduced into clay muds 3 as inhibitors. The increase in the stability of clay rocks is based on the replacement of monovalent cations with polyvalent cations, chemisorption of polyvalent cations, and the coagulating action of Cl in the exchange complex of clay.

However, these solutions have a number of significant drawbacks, namely: complexity, difficulty adjusting filtration and rheological properties, increased consumption of fluid loss reducers and thinners. Low heat resistance.

Closest to the invention is a mud containing clay, water, a fluid loss reducer and phosphonic complexones — nitrolotrimethylphosphonic (NTF) and 1-hydroxyethylidene diphosphonic (OEDP) acids in an amount of 0.01–0.03%. The use of known drilling mud in unstable clay rocks is possible due to the fact that complexones at concentrations of 0.01-0.03% are highly effective thinners and allow maintaining stable structural and mechanical parameters of the drilling mud when the dispersed rock passes into it. 2 J.

However, limestone solution does not prevent the swelling of clays and, therefore, cannot ensure the sustainability of the wellbore.

The aim of the invention is to increase the inhibitory properties of the drilling fluid.

The goal is achieved by the fact that the mud containing clay is a fluid loss agent.

Nitrilotrimethylphosphonic acid or 1-hydroxyethylidene diphosphonic acid and water, contains components in the following ratio, wt.%:

Clay. 8-25

Water loss reducer 0.01-0.3

Nitrilotrimethylphosphonate

acid or 1-hydroxyethyliden0, 5-2.0 the Rest

Phosphonic complexones correspond to the following structural formulas:

nitrilotrimethylphosphonic acid (NTF)

, RO (OH) 2

1-hydroxyethylidene-with PO (OH), diphosphonic acid (HEDP)

he

Phosphonic complexones are highly efficient complexing agents and are capable of chemisorption on clay particles. At low concentrations of the reagent (0.01-0.03%), the adsorption is energetically more favorable along the edges of the silicate planes having uncompensated valencies and free charges, since in this case chemical bonds are formed. Chemisorption at the edges prevents clay particles from approaching the most active & w segments and prevents drilling mud from becoming shattered.

With an increase in the concentration of phosphonic complexones to 0.5-2.0%, clay particles begin to adsorb on the basal planes, mainly due to electrostatic as well as hydrogen bonds formed. This leads to the hydrophobization of the surface of clay minerals due to carbon-hydrogen fragments included in phosphonic complexones, and helps reduce clay swelling. The essence of the inhibition process is to mix the hydrophilic hydrophobic balance of clay towards increasing its hydrophobicity. The degree of inhibition of clay rocks is estimated by reducing the swelling and dispersion of clay in the inhibitor medium. Example. 80 g of bentonite clay powder or clay sludge from the Samotlor field is dispersed in 1000 ml of water, then a water loss reducer is introduced - 1 ml of 10% rd aqueous solution of CMC-600 or 0.2 ml of a 2% aqueous solution of polyacrylamide and mixed until complete dissolving. Separately, an aqueous solution of the phosphonic complextex is prepared by dissolving 5 g of acid in a small amount of water and treating with commercial alkali to pH 7. The stabilized clay slurry is mixed with komplakson for 1-2 h, then the parameters of the drilling fluid are measured. The inhibiting properties of the solution are determined by the swelling of bentonite using the instrument of the Zhigach-Yarov construction. The swelling constants are determined graphically. The swelling indices are as follows: K - swelling coefficient, equal to the ratio of the volume of liquid. U.,., Associated with the breakdown, to the volume of dry particles Kj - swelling coefficient,. equal to the ratio V .. to the weight of the dry sample ha; K is the amount of swelling fluid (cm) connecting 1 g of clay. The determination of the degree of swelling of the bonitite is carried out in the solutions listed in Table 1. Potassium and calcium solutions were selected for comparison as the Best Swelling Inhibitors at concentrations corresponding to the maximum inhibition effect. Solutions of phosphonic complexones are prepared by dissolving the required amount of reagent in water, then the product base is added to pH 8-9. The effect of the concentration of phosphonic complexones on the indicators of swelling of bentonite, which characterize the inhibitory effect, is given in Table 1. To determine the clay content of the solutions, inhibitor solutions are prepared, to which bentonite clay is added in portions of 10–20 g. After mixing the solutions, the static shear stress (sleep) characterizing the presence of the structure in the clay solution is measured. The amount of added clay at which are the first measurable values of SNS (on the SNS-2 instrument) characterizes the amount of clay content of the inhibitor solution. The alumina capacity of water is assumed to be 1. The composition of the studied solutions and their alumina capacity are shown in Table 2. As can be seen from the data of Table 2 on the effectiveness of reducing the swelling and dispersion of clay rocks, phosphonic complexes are at the level of such widely used inhibitors as calcium and potassium compounds. The composition and technological parameters of drilling fluids are given in table 3. Thus, the technological parameters of solutions containing 0.5-2% phosphonic complexions are easily controlled, there is no need to increase the content of fluid loss reducers and apply thinners. Solutions are heat resistant up to. Table 1

j1098951

Continued table. 2

Continued tabl, 2

-0.3-0 .10 .220 -. ABOUT,

25 -O,

25 Oh, ..Note. The heating of the solutions is carried out at

Glazing capacity

water, constituting 60 g of clay per 500 MP of solution, assumed equal to 1.

Table 3

Parameters. Solutions 180 ° С for 8 h.

Claims (1)

A DRILLING Mud containing clay, a fluid loss reducer, nitrip’o • trimethylphosphonic acid or 1-hydroxyethylidene diphosphonic acid and water, characterized in that, in order to increase the inhibitory properties of the solution, it contains components in the following ratio, wt.%: Glyne 8-25 Fluid loss reducer 0.01-0.3 Nitrilotrimethylphosphonic acid or 1-hydroxyethylidene diphosphonic acid 0.5-2.0 Water Else