SU972328A1 - Rotary viscometer - Google Patents

Description

(54) ROTATIONAL VISCOSIMETER

one

The invention relates to devices for measuring the physicomechanical properties of the liquids under investigation, in particular to devices for measuring the rheological characteristics of drilling fluids.

A rotary viscometer is known, which contains an outer cylinder located in a housing, an inner cylinder mounted on a torsion bar, which in turn is attached to the housing through a turning mechanism 1.

The disadvantage of this viscometer is low accuracy in measuring liquids with a thixotropic structure.

Closest to the present invention is a fluid viscosity measuring device which contains three coaxially disposed cylinders, a first cylinder connected to a measuring system, a second cylinder made with radial openings in the upper part and connected to an electric drive, and the third is a sampler. When the second cylinder rotates in a coaxial gap, an axial flow is created under the action of centrifugal forces.

the drilling fluid is transported through the radial holes into the sampler, and from the sampler into the coaxial gap, i.e., circulation begins to prevent heavy dispersed particles (loose fluid) of the test mud from falling out. Thereby, the error in measuring the rheological characteristics of the drilling fluid 2 is reduced.

The described above circulation of the drilling mud 10 leads to uneven destruction of the thixotropic structure in the coaxial gap between the cylinders and the sampler, which leads to errors in determining the rheological characteristics.

The purpose of the invention is to improve the accuracy of measuring the rheological characteristics of the test solution by creating conditions for uniform destruction of the thixotropic structure of the liquid.

This goal is achieved by the fact that in a 20 rotational viscometer containing three coaxially arranged cylinders, the first of which is connected to the measuring system, the second is rotatable and contains radial holes in the upper part, the second cylinder is located between the first and third, coaxial gaps cylinders are selected based on the ratio (- 1- (V where T BI is RH is the inner and outer radii of the second cylinder; g is the outer radius of the first cylinder; Poison is the inner radius of the third cylinder. Necessity The relationship follows from the following considerations: The degree of destruction of the thixotropic structure of dispersed systems can generally be characterized by the energy expended to deform.The energy expended / is proportional to the shear stress, shear rate, deformation time. Consequently, for a particular fluid during the measurement on the viscometer the deformations are equal, and the kinematic characteristic of the deformation process is the shear rate. The shear rate for coaxial cylinders can be expressed as follows for a pair of measuring cylinders 15 l- (fJ1 where n is the rotational speed of the outer cylinder, rpm. For a pair of loosing cylinder is a sampler. Un / Based on the identical destruction speed of the thixotropic structure of the CN UE a constructive relation 1 - (- 1 -f f. CV Rn

The drawing shows a schematic diagram of the device.

The viscometer contains two coaxial cylinders, one of which is rotating, the second cylinder 2 with radial holes 3 in the upper part is connected to the electric motor 4, and the other fixed first cylinder 1 is connected to the measuring system . Both cylinders 1 and 2 with a coaxial gap 7 are placed in the third cylinder 8, which serves as a sampler for the liquid under study.

The device works as follows

The third cylinder 8 is filled with the test liquid. Turn on the electric motor

 - 1 - (B; f,

f

where r is the outer radius of the first cylinder; RB and RH-internal and external radii

second cylinder;

Rn is the inner radius of the third cylinder.

Sources of information taken into account in the examination

1. USSR author's certificate number 328375, cl. G 01 N 11/14, 1970.

2. US patent number 4077251,

Claims (2)

cl. G 01 N 11/14, 1979 (prototype). 4, which transmits rotation to the second cylinder 2. In the coaxial gap 7, a vertical flow of liquid is created through the radial holes 3, made in the upper part of the rotating second cylinder 2, which prevents the dispersion of dispersed particles (ut g) from settling. At the same time, fresh portions of the test solution coming from the sampler — the third cylinder 8 — into the coaxial gap 7 between cylinders 1 and 2 have an identical degree of destruction of the thixotropic structure of the test solution. In the coaxial gap 7, the fluid is deformed, creating a torque on the stationary cylinder 1, which twists the compensation spring 5 at a certain angle fixed by the clamp 6. The scale parameters of rotation of the scale 6 at several speeds of rotation of the second cylinder 2 are calculated, but the dependencies are calculated according to the known characteristics fluid. The use of the proposed rotational viscometer with a predetermined gap ratio will reduce the measurement error of the rheological parameters of drilling fluids, which contributes to an increase in the mechanical drilling rate and a reduction in emergency situations. Claims of the invention: A rotational viscometer comprising three coaxially arranged cylinders, the first of which is connected to the measuring system, the second one is rotatable and contains radial holes in the upper part, the second cylinder being located between the first and the third, in order to increase accuracy of measurements of liquids with a tick of a sotropic structure, coaxial gaps of cylinders are selected, based on the ratio