RU1556099C - Clayless drilling liquid - Google Patents

Abstract

FIELD: hole drilling. SUBSTANCE: liquid has the following components at their ratio, wt. -% : acrylic polymer 0.001-0.035; trivalent metal salt 0.003-0.30; cellulose ester 0.1-0.3, and water - the rest. Source of acrylic polymer in liquid: polyacrylamide, or methas, or methacryl-14; source of trivalent metal salt: aluminium sulfate, or ferric sulfate, or aluminium chloride, or ferric chloride. Source of cellulose ester: liquid has carboxymethylcellulose at polymerization degree from 350 to 700, or hydroxyethylcellulose. Both technical and deposit water can be used for liquid preparing. Liquid is prepared by mixing of components. EFFECT: enhanced quality of productive layer opening, improved indices of working, diminished cost for preparing ant treatment of drilling liquid, increased flocculation rate. 4 tbl

Description

 The invention is intended for drilling wells for oil, gas and water, it is a clay-free drilling fluid used to flush wells during drilling and opening productive formations under conditions complicated by screes and landslides of clays and mudstones.

 The goal is to increase the ability to restore technological properties after removing cuttings while increasing the rate of flocculation.

The solution contains ingredients in the following ratio, wt.%: Acrylic polymer 0.001-0.035
Trivalent metal salt 0.003-0.030 Cellulose ether 0.100-0.300 Water Else
As an acrylic polymer, the solution contains polyacrylamide (PAA) or metas, or methacryl-14, and as a salt of a trivalent metal - or aluminum sulfate, or iron sulfate, or aluminum chloride, or iron chloride.

 As a cellulose ether, the solution contains either carboxymethyl cellulose with a polymerization degree of 350 to 700, or hydroxyethyl cellulose.

 To prepare the solution, you can use both technical and produced water.

 The solution is prepared by mixing the ingredients.

PRI me R. To 939 g of water add 40 g of a 5% solution of CMC-700, after 30 minutes of stirring add 1 g of a 10% solution of iron chloride. The mixture is stirred for 15 minutes, after which 20 g of a 0.5% solution of polyacrylamide (Polydia) are added to it. After stirring for 30 minutes, a clay-free drilling fluid is obtained having a composition, wt.%: Carboxymethyl cellulose 0.2; PAA 0.01; FeCl ₃ 0.01; process water - the rest is usable.

 Similarly received other compositions of clay-free drilling mud with different ratios of ingredients, are given in table. 1. In the table. 2 shows the results of their study.

To obtain a clay-free drilling fluid in laboratory conditions, the following substances were used:
formation water with a density of 1180 kg / m ³ with a total salinity of 260 g / l and a calcium chloride content of 52 g / l;
process water (tap) with a hardness of less than 5 mEq / l;
domestic polyacrylamide, iron-like substance with a basic substance content of 6-8%; in the experiments, a 2% aqueous solution was used;
Japanese-made polyacrylamide brands DK-DrillA-1, A-15, Polydia, a dry, powdery substance of white color, in the experiments a 0.5% aqueous solution was used;
carboxymethyl cellulose (CMC), KMTs-500, KMTs-600 or KMTs-700, fine-grained, powdery or fibrous substance of white color, 5% aqueous solution was used in the experiments;
carboxymethyl cellulose - SMS В-805 of Japanese manufacture, a white powder substance, in the experiments a 5% aqueous solution was used;
hydroxyethyl cellulose (OEC), a white powdery substance, used in the experiments a 5% aqueous solution;
metas - acrylic polymer reagent, white powder, in the experiments we used a 2% aqueous solution prepared in a 0.5% NaOH solution;
copolymer M-14 — suspension methacryl-14 copolymer is a highly viscous, white powdery substance; in the experiments we used a 1% aqueous solution prepared on a 0.3% NaOH solution;
aluminum sulfate, white powder, in the experiments used a 10% aqueous solution;
potassium sulfate - aluminum, white powder, in the experiments used a 5th aqueous solution;
ferric chloride, a crystalline substance of dark yellow color, in the experiments used a 10% aqueous solution;
iron sulfate, a yellow crystalline substance, in the experiments used a 10% aqueous solution;
aluminum chloride, a white powdery substance, in the experiments used a 10% aqueous solution.

In the course of laboratory studies, the following properties of clay-free drilling fluid were determined: density (δ, kg / m ³ ), conditional viscosity (UV ₁₀₀ , s), filtration rate (Φ, cm ³ for 0.5 h using a VM-6 device). During laboratory studies, the flocculating properties of the clay-free drilling fluid were also determined, and the filtration rate and the conditional viscosity of the clay-free mud after exposure to drill cuttings were measured (the properties of clay-free mud were judged by changing the values of the filtration index and conditional viscosity after exposure to the cuttings).

 To obtain comparative data in the course of laboratory studies, similar properties of known clay-free drilling fluids were determined.

 The study of the flocculating properties of clay-free drilling fluids and the assessment of the stability of their filtration and rheological properties in relation to the cuttings were carried out according to the following method. After preparation of the clay-free drilling fluid, its density, filtration rate, and viscosity were measured. Then, the flocculating properties of the drilling fluid were determined; for this, 6% clay powder was added to the solution with stirring (Almetyevsk clay powder was used in the experiments). The solution with clay powder was stirred for 0.5 h on a high-speed laboratory stirrer at a speed of 2500 rpm.

 After stirring, the density of the solution was measured and the solution was poured into 4 graduated cylinders with a volume of 100 ml each having openings in the middle closed by a stopper. The stopwatch was turned on and the density of the upper half of the solution was measured after 3, 10, 30 and 60 minutes. The change in the density of clay-free drilling mud over time was used to judge the rate of deposition of the solid phase, i.e. about flocculating properties of clay-free drilling fluids.

 After measuring the flocculating properties, the density, the filtration rate, and the conditional viscosity of the solution were measured after the clay powder was precipitated from it.

Analysis of the data presented in table. 1 and 2, shows that the solution has low values of the filtration index (from 2.5 to 10 cm ³ ), low viscosity values (from 3.6 to 4.2 s), the solution has high flocculating properties (after 3 min it precipitates 94.2-100% of the solid phase introduced into the solution) and is resistant to filtration and rheological properties to the effect of cuttings (after sedimentation and removal of the solid phase, the properties of the solution remain unchanged).

 Since the solution can also be prepared with produced water (PV), the solution obtained in this case has high inhibitory properties due to the presence of electrolytes contained in the produced water, as a result of which such a drilling fluid ensures the stability of the borehole walls during drilling.

The above values of the ingredients are boundary, i.e. their changes to a greater or lesser extent do not allow to achieve the set goal of the invention. So, when the concentration of cellulose ethers is less than 0.1% and the content of acrylic polymers is less than 0.001% (solution 4), the clay-free solution, although it has satisfactory values for the filtration rate of the initial solution (12 cm ³ ), is not resistant to drill cuttings, since the filtration rate after flocculation increases to 17 cm ³ . With a concentration of cellulose ethers of more than 0.3% and acrylic polymers of more than 0.035% (solutions 9, 12, 13 and 16), clayless drilling fluids have low flocculating properties. When the concentration of salts of trivalent metals is less than 0.003% and more than 0.03%, clay-free solutions have high values of the filtration rate (solutions 20 and 22). When using only one polymer, either acrylic (solutions 2 and 3) or cellulose ether (solution 13) in combination with salts of trivalent metals, the object of the invention is not achieved, since these solutions have either low flocculating properties or high values of the filtration rate.

 A comparison of the properties of this solution with the known ones (see Table 3) shows that the latter (solutions 1, 2, and 3) do not retain their properties after removing the solid phase from them. They possess this property only when a solid phase is included in their composition (their flocculating properties are low), but it is worth removing it and the properties sharply worsen.

 In addition, in known solutions, cellulose ether (in particular KMC-600) without lignosulfonates does not provide low filtration rates even in the original clay-free solutions, i.e. solutions obtained according to the well-known recipe excluding lignosulfonates are characterized by a high filtration rate (see table. 3, solutions 3 and 6).

 The effect achieved by the described drilling fluid, as shown by the following experiments, is ensured by the combined action of all three components of the system (acrylic polymer, cellulose ether and salts of trivalent metals) and does not follow from the known properties (direct functional purpose) of each of these components.

When conducting experiments, first prepared a composition of two ingredients of the claimed solution, then 6 wt.% Almetyevsk clay powder (AG) was added there, and then the third component was introduced. Then, the flocculating properties of the resulting solution and its properties after removal of the solid phase were determined. The data obtained during the tests are given in table. 4. Their analysis shows that when clay powder is introduced into a mixture of two solution components [PAA + + Al ₂ (SO ₄ ) ₃ ; CMC + Al ₂ (SO ₄ ) ₃ or PAA + CMC] it is not possible to obtain the described drilling fluid by additives of the third component (CMC, PAA or Al ₂ (SO ₄ ) ₃ , since a drilling fluid resistant to drill cuttings can be obtained only with the simultaneous interaction of all three components of the solution, in this case a stable system is formed, which is characterized by quality indicators even after removal of the cuttings.

 In all three experiments (see Table 4), the cellulose ether did not exhibit a stabilizing effect, and the synergistic effect did not also appear when combined with polyacrylamide and cellulose ether (see experiment 3 in Table 4).

 The indicated technical advantages of this non-clay drilling mud when using it allow you to: improve the quality of opening of reservoirs by reducing by 1.5 times compared with the known solutions of the penetration of the dispersion medium and the dispersed phase of the drilling fluid into the reservoir (due to the low values of the filtration rate during drilling and high flocculating properties of the solution); to improve the performance of the bits (increase penetration to the bit and mechanical speed by 15-20%) due to the high flocculating properties of the solution; to reduce by 2-3 times the cost of drilling fluid by reducing the consumption of chemicals (due to the high stability of the filtration and rheological properties of the fluid to the effects of drill cuttings and the high flocculating ability of the fluid).

Claims (1)

A CLAY-FREE DRILLING Mud including an acrylic polymer, a trivalent metal salt and water, characterized in that, in order to increase the ability to restore technological properties after removing drill cuttings while increasing flocculation rate, it additionally contains cellulose ether in the following ratio of ingredients, wt.%:
Acrylic polymer - 0.001 - 0.035
Trivalent metal salt - 0.003 - 0.030
Cellulose ether - 0.100 - 0.300
Water - Else

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