SU1724672A1 - Water-base drilling mud - Google Patents

Abstract

The invention relates to the drilling of oil and gas wells. The aim of the invention is to improve drilling performance by increasing the outgoing ability of the solution while improving the anti-sticking properties of the mudcake. For this, the water-based drilling fluid contains clay, a stabilizer, an additive and water. As an additive, plastic microspheres of phenol-formaldehyde resin are used in the following ratio of ingredients, wt.%: Clay 5-15; stabilizer 0.5-1.5; phenol-formaldehyde resin plastic microspheres 1,3; water is the rest. This drilling mud has a high out-put ability, which helps to improve the cleaning of the bottom-hole rock and, as a result, increase the drilling performance. The high anti-sticking properties of the mudcake on the mortar help to prevent accidents associated with the sticking of the drilling tool and the descent of casing strings. 5 tab. C /) with

Description

The invention relates to the oil industry, in particular to water-based drilling fluids for drilling oil and gas wells.

The purpose of the invention is to improve drilling performance by increasing the outgoing ability of the solution while enhancing the anti-sticking properties of the mudcake.

The goal is achieved by a water-based mud containing clay, a stabilizer, an additive and water, in which plastic microspheres of phenol-formaldehyde (f / f) resin are used as an additive in the following ratio of ingredients, wt.%:

Clay5-15

Stabilizer 0.5-1.5

Plastic microspheres of phenol-formaldehyde resin 1-3 Water Else

Plastic microspheres are prepared by spray drying a composition containing f / f resin (for example, BZ-3) and a reagent - a blowing agent (porous porcelain grade CHZ-57) in the following ratio of ingredients, wt.%: Reagent - a blowing agent 1-3; F / F resin else. Known applications of plastic microspheres: for the preparation of syntactic foams, as a facilitating filler for drilling and plugging solutions.

Example 1: In 935 g of water, shutter 50 g of clay (bentonite) and mix for 1 hour until the clay has completely dissolved. For “HS &

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5 g of stabilizer (CMC) are then added and stirred for another 0.5 h, after which 10 g of plastic microspheres of f / f resin are introduced, stirred for 20 min and the solution is considered ready.

Example 2. In 870 g of water, 100 g of clay (bentonite) are shutter and stirred for 1 hour until the clay has completely dissolved. Then, 10 g of a stabilizer (CMC) is added and stirred for another 0.5 h, after which 20 g of plastic microspheres of f / f resin (grade BZ-3) are introduced, mixed for 20 min and the solution is considered ready.

PRI me R 3. In 805 g of water, shutter 150 g of clay (bentonite) and mix for 1 hour until the clay has completely dissolved. Then, 15 g of a stabilizer (CMC) is added and stirred for another 0.5 h, after which 30 g of plastic microspheres of f / f resin (grade BZ-3) are introduced, stirred for 20 minutes and the solution is considered ready.

Improvement of drilling performance (drilling for a bit and mechanical drilling speed) can be achieved in different ways: by optimizing drilling conditions, increasing the power supplied to the bit, reducing the back pressure to the bottom hole, etc. One of the ways to improve drilling performance is to improve the removal of cuttings from the bottom. For example, when drilling mud is aerated, an improvement in the removal of drill cuttings from the bottom of the well and, as a result, an increase in drilling rates is noted. However, aerated drilling mud can be used only under certain geological and technical conditions: at low reservoir pressures, for drilling relatively shallow wells, which is limited by the power of the produced compressor units. In addition, during aeration, additional equipment is required (compressor, ejector, vent device, etc.) and maintenance personnel.

More effective for enhancing drilling performance is the introduction to bu-. An even solution of some solid additives, hollow or monolithic, having a spherical shape and relatively small size. For example, it is proposed to introduce monolithic glass or plastic beads of two sizes, 0.65 and 0.25 mm, into the solution. They are introduced into the solution in the amount of 11.5-17 kg / m3 solution. These balls, embedded in a mudcake, play the role of tiny bearings, which drastically reduces the risk of sticking and greasing. The drawbacks of drilling fluids with plastic or glass

the balls are: a slight increase in drilling rates (on average by 15–20%) as a result of the relatively low efficacy of the solution, due to the fact that monolithic balls are used,

which have a density greater than or equal to the density of the drilling mud; glass balls cause abrasive wear of drilling and rock cutting tools.

0 For comparison, the drilling fluid without the addition of plastic microspheres, the drilling fluid with the addition of plastic microspheres from urea-formaldehyde (m / f) resin of the brand UKS, and the drilling fluid with the addition of glass microspheres are also being investigated.

In tab. 1 shows the component compositions of the studied solutions, Composition 1 is a clay solution without the addition of micro-spheres. In compositions 2-6, plastic microspheres of f / f resin BZh-3 were used (i.e., this is the proposed solution). Moreover, in composition 2, the concentrations of the components are below the boundary values, in compositions 3-5-5, the optimum values of the components, and in composition 6, the concentrations of the components are higher than the boundary values.

In compositions 7-9 were used plastic microspheres of f / f resin VZH-3

0 in high concentrations. In compositions 10-12, glass microspheres were used, and in compositions 13-15, plastic microspheres from m / f resin of the brand UKS were used. In all experiments, plastics and glass were used.

5 microspheres of one narrow fraction: 100-150 microns.

In tab. 2 shows the main technological parameters of the solutions, the compositions of which are given in table. one.

0 As follows from the table; 2 data, the technological parameters of the proposed solution with concentrations of components below the boundary values (composition 2) are bad: high filtration rates, low structural and mechanical properties. At concentrations of components above the boundary values (composition 6), the solution thickens substantially, the viscosity and structural and mechanical properties increase.

0 that may negatively affect drilling rates.

The most acceptable parameters for solutions with the proposed values of the components (compounds 3-5). With the introduction of

5, the clay solution of plastic microspheres of f / f resin (compounds 7–9), the solution becomes excessively thickened, and a thick crust of clay is formed. When glass microspheres are introduced into the clay solution (compositions

10-12) or plastic microspheres made from m / f resin (compositions 13-15), the technological parameters of solutions practically do not differ from similar indicators of solutions with the addition of plastic microspheres from f / f resin (compositions 3-5).

Under laboratory conditions, the removal capacity of the solutions was investigated by pumping them using a centrifugal pump (from an ultra-thermostat) through a tubular column (of plexiglas), in which a sample of drill cuttings (sludge) was placed. The speed and circulation time, pump performance and other parameters were the same in all experiments and simulated the conditions of a real well. The slurry had the following friction composition,%: 10 mm 3.8; 5 mm 16.4; 2.5 mm 42.7; 1.5 mm 33.1; 1 mm 4.

After three cycles of solution circulation, the pump was turned off, the remaining sludge in the column was washed, dried to constant weight, weighed and scattered in fractions. Then calculated as a percentage of the amount of sludge removed from the column from the column of the total and by fraction. Table. 3 presents the results of these experiments.

The mechanism for improving the carrying capacity with the introduction of plastic microspheres from f / f resin is caused, firstly, by the effect of the microspheres slipping (popping) relative to solution-. as a result of a significant difference in the densities of the microspheres and the solution, which causes the effect of early turbulence and thereby an improvement in the removal of drill cuttings from the well bottom. Secondly, the improvement of the removal contributes to the adhesion of the particles of cuttings to the hydrophobic surface of the microspheres of f / f resin.

Both the effect of early turbulence and the sticking effect of the particles of the cuttings substantially depend on the nature of the wettability of the surface of the plastic microspheres — it must be hydrophobic (i.e. the wetting angle must be more than 90 °). Therefore, when using microspheres made from m / f resin or glass microspheres having a hydrophilic surface (their wetting angle is 46 and 32 °, respectively), the aim of the invention is not achieved .....

Phenol-formaldehyde resin microspheres, such as BZ-3, used in the invention have a pronounced hydrophobic surface (wetting angle is 162 °). Microspheres of the same resin BZ-3, modified organoaluminosiliconate

sodium, have a less pronounced hydrophobic surface (the wetting angle is 128 °) and, therefore, the effect of the carrying capacity of using these microspheres will be lower. To prove this, we carried out laboratory tests of the outgoing ability of solutions with various types of microspheres, including those from f / f resin, modified with organoaluminosiliconate sodium.

From tab. 3, it can be seen that the proposed drilling fluid with optimal concentrations (compositions 3-5) has a high out-of-reach capacity, superior to that of a known solution (compositions 7-9). This applies mainly to coarse sludge fractions of 5 and 10 mm. Moreover, with an increase in the concentration of microspheres in a known solution, the removal of these sludge fractions deteriorates somewhat. This is due to the deterioration of the flotation effect of the microspheres as a result of the thickening of the solution.

5 Of great importance is the nature of wetting the surface of the microspheres. Microspheres of f / f resins have a hydrophobic surface, while microspheres of f / f resins and glass microspheres are hydrophilic.

0 Hydrophobic microspheres adhere well to cuttings particles and due to the flotation effect they are removed from the column. Hydrophilic microspheres do not adhere to the sludge particles, and therefore

5, the ability of solutions with glass microspheres (compounds 10–12) and with micro / spheres made from m / f resin (compositions 13–15) is much worse compared with the proposed solution. Good cleaning

0 Zabo from drilled rock will improve drilling performance.

Using this stand, rock samples (in this case, marble) were drilled with 33 mm microdits with three carbide cutters. Mining and hydrostatic pressure, drilling mode, etc. were simulated. The solution was circulated using the NVU-30 pumping unit (capacity up to 30 l / min). The measure of the drilling efficiency was taken as the magnitude of the mechanical speed of drilling.

In tab. 4 presents the data on the obtained values of the mechanical velocity.

5 drilling samples of marble.

The data table. 4 indicate that the proposed solution with optimal concentrations of the components (compounds 3-5) allows a significant increase in the mechanical drilling rate. It is 3-5 times higher than when using the original clay solution (composition 1), 3.5-4 times higher than the known solution (compositions 7-9) and 1.5-2 times higher than solutions in which glass microspheres (compositions 10-12) or m / f resin microspheres (compositions 13-15) were used.

The large difference in drilling rates with the use of the proposed and known solutions is explained not only by the latter's lasting ability, but also by the negative effect on the mechanical drilling rate of the excessively high viscosity and structural-mechanical properties of the known solution.

If in the proposed solution the concentration of microspheres from the f / f resin is less (composition 2) or more (composition 6) of the boundary values, then the mechanical drilling rate decreases. In the first case, due to the insufficient concentration of microspheres in the solution, and in the second, as a result of an increase in the viscosity and structural-mechanical properties of the solution.

Under laboratory conditions, the studied and sensitive properties of the muddy crusts formed during the filtration of solutions, the compositions of which are presented in Table. 1, Anti-sticking properties of crusts were evaluated by the coefficient of shear crust (CSC), measured using an upgraded standard SNS-2 device. The device is supplemented with a prefix that includes a ring-shaped weight connected pivotally to the harness. To determine the twist angle of the instrument, the peel together with the paper filter is placed on the movable table of the instrument. The suspension system is installed in such a way that the ring is above the surface of the peel at a distance of about 1 mm. Then the locking screw holding the ring is lowered, and it sticks under its own weight to the mudcake. The electric motor of the device is switched on and the table with a mudcake is set in rotation, this entails a twisting of the thread of the suspension system. The maximum twist angle of the thread, recorded at the time when the suspension system stops rotating, is used to calculate the KSK using the formula

KSK

 C-FF,

R R

where C is the constant of the wire (thread) of the device, g / cm;

B is a constant number equal to 75.36 cm / deg;

F is the area of the ring, cm2;

Q - maximum twist angle of the thread, hail;

R is the average radius of the ring, cm;

P is the weight of the ring,

The lower the KSK value, the worse the anti-grip properties of the clay crust.

In tab. 5 presents data on the magnitude of the KSK measured at the crusts of the studied solutions.

As follows from the data table. 5, clay-5 hundred crusts of the proposed solution with optimal concentrations of the components (compounds 3-5) has high anti-sticking properties (low KSK), much higher than the anti-sponge properties of the crust of the original clay solution (composition 1). Microspheres, embedded in a mudcake, then perform the role of micro-ball bearings. The concentration of 5 microspheres in the solution, the material from which they are made, is important.

So, if the concentration of microspheres from f / f resin is too high, as is the case in the known solution - (compounds 7-9), 0 gets too thick, loose crust and its anti-sticking properties are low (high KSK). Also, lower anti-sticking properties of crusts obtained from solutions with glass microspheres (compositions 10–12) and m / f resin microspheres (compounds ISIS). In the first case, due to the high hardness and abrasiveness of glass microspheres, and in the second, due to the low mechanical strength of the m / f resin microspheres, which are destroyed in the course of the experiment.

When the concentration of microspheres of f / f resin in the proposed solution is below the boundary values (composition 2), the anti-sticking properties of the mudcake deteriorate due to the insufficient number of microspheres in the solution. The deterioration of the anti-sticking properties is also noticeable with increasing concentrations of these microspheres above the boundary values (composition 6) due to the increase in the thickness of the mudcake and its looseness.

Thus, the proposed drilling mud has the following technical and eco-friendly advantages as compared with the known formulations. High wearing capacity helps to improve the cleaning of the borehole from the drill cuttings and, as a consequence, to increase drilling rates. The high anti-sticking properties of the mudcake at the proposed solution will help prevent accidents associated with sticking of the drilling tool and the descent of casing strings.

Claims (1)

Claims A water-based drilling mud containing clay, a stabilizer, an additive and water, characterized in that, in order to improve drilling performance by increasing the out-of-bearing ability of the mud 0 while improving the anti-sticking properties of the mudcake, the solution contains, as an additive, plastic microspheres of phenol formaldehyde resin in the following ratio of ingredients, May. %: Clay5-15 Stabilizer 0.5-1.5 Plastic microspheres of phenol-formaldehyde resin 1-3 Water Else 12 3 h 5 6 7 8 9 10 11 12 13 1h 15 T a .6 l and c a 1 1.0 2.0 oh oh 1.0 2.0 3.0 The rest | Cyp and n || n m and pn n Table 2 Table3 Table5 Composition one ksk Table