Measuring and testing – Borehole or drilling – Downhole test
Patent
1980-05-22
1982-07-27
Myracle, Jerry W.
Measuring and testing
Borehole or drilling
Downhole test
E21B 4700
Patent
active
043411150
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the preparation and regeneration of drilling mud. More particularly, the invention relates to a method of monitoring structural and mechanical properties of drilling mud and a device for realizing same.
The present invention can be most advantageously used in petroleum and gas industries for preparation of mud.
This invention can also be successsfully employed for regeneration of mud, that is for regeneration of initial properties of mud.
2. Prior Art
At present, clay mud is extensively used in drilling holes of various depths.
Structural and mechanical properties of drilling mud based on clay are often characterized by the viscosity of mud, which is determined by rotary viscosimeters of various designs. Besides, such properties can be characterized by shear strength which can be found by means of laboratory methods.
Structural and mechanical properties of clay drilling mud are currently often defined by the so-called "coagulation index" (CI) which is in fact the ratio of the shear strength to the viscosity of mud. This index characterizes the degree of coagulation of mud.
In modern practice, both characteristics are measured manually and independently, that is, the viscosity is measured by viscosimeters of any type, whereas the shear strength is found by means of a special instrument for measuring the shear strength. Manual measurements are time consuming and irregular, so that accuracy is unavoidably impaired. This, as may be expected, permits no uninterrupted monitoring of mud condition in the process of preparation and during circulation in the hole, which are vital prerequisites of successful hole sinking.
This is also a disadvantage as far as automation of mud preparation is concerned.
SUMMARY OF THE INVENTION
The principal object of the invention is to provide a method and apparatus for monitoring structural and mechanical properties of drilling mud which permit continuous comparison of the values of the shear strength and the viscosity of the drilling mud.
An object of the invention is to provide a method and appartus for the continuous monitoring of the structural and mechanical properties of drilling mud, whose parameters vary fairly frequently, with measurements of high accuracy, thereby providing for better quality and stability of drilling mud.
Another object of the invention is to provide a method and apparatus for the continuous monitoring of the structural and mechanical properties of drilling mud wherein the regeneration of the properties and parameters of mud in the process of circulation is accomplished in considerably less time than in known methods.
The method of monitoring structural and mechanical properties of drilling mud of the invention comprises measurement of the viscosity of the mud by a viscosimeter featuring a driven sensitive element and measurement of the shear strength of the mud via an instrument for measuring the shear strength, having a driven sensitive element. The driven sensitive elements are immersed in the drilling mud in order to obtain figures characterizing each parameter being measured. Later, the figures thus obtained are compared. in accordance with the invention, the sensitive elements are connected to the same pole of the power source. An electrode connected to the opposite pole of this power source is immersed in the drilling mud. Current flowing between the electrode and the sensitive elements is measured. When the current is stabilized, electrical signals are obtained, which are proportional to the viscosity and shear strength of the mud. A first ratio of the shear strength and viscosity signals is determined and then the polarity of the power source poles is reversed and a second ratio of the shear strength and viscosity signals is determined. Then, the arithmetical mean of the first and second ratios is calculated.
It is advisable that the method of the invention be realized by apparatus comprising a viscosimeter having a driven sensitive element immersed in the
REFERENCES:
patent: 2266733 (1941-12-01), Bays et al.
patent: 3289467 (1966-12-01), Parker et al.
Alekhin Stanislav A.
Bakhir Vitold M.
Born Raisa I.
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