RU2566160C1 - Water loss control method for circulating fluid - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: while implementing the method, when producing formation is drilled from access point of the rock cutting tool, in circulating system of the well moisture and density of circulating fluid are measured simultaneously and continuously, against these measurements current volume content of free water is calculated for circulating fluid as per the specified formula, and water loss is defined with well deepening against difference in volume content of water for circulating fluid at inlet into the drilled formation and at outlet from it.

EFFECT: increased information content and control authenticity, reduced time and labour costs for performance of auxiliary operations.

Description

The invention relates to the drilling of oil and gas wells and can be used for automatic continuous monitoring of the parameters of drilling fluids in the process of drilling rocks.

A known method of controlling the fluid loss of a washing fluid with visual measurement readings during well drilling is based on the determination of the volume of free (not chemically related to the dispersed phase) water that is capable of penetrating into the reservoir under the influence of pressure differences from an arbitrarily specified volume of the studied washing fluid withdrawn from well circulation system. The essence of this method consists in periodically measuring the volume of free water (filtrate) removed from the next test portion of the washing liquid through a paper filter by squeezing with the help of a piston system that creates excess pressure for a selected period of time. By changing the filtrate volumes thus obtained, one can judge the rate of filtration of free water from the wash liquid into the reservoir. To implement this method, BM-6 devices, widely known in drilling practice, are used, which allow for a pressure difference of 0.1 MPa to determine, on a linear scale, the volume of free water in cm ³ released from the washing liquid sample in 30 minutes through a paper filter with a diameter of 75 mm [ 12].

The specified method does not have sufficient informativeness and reliability of control, which leads to the opening of productive formations with the parameters of the flushing fluid, very far from optimal. This is because the simulation of the control of water loss carried out by squeezing out the volume of the filtrate depends on the design features of the device used and, when transferred to downhole conditions, it does not reflect the real ability of the washing liquid to water loss during drilling. This is due to the dependence of the water loss on such factors as the composition of the washing liquid, the dispersion of solid particles, the pressure drop, temperature, the filtration resistance of the formation, the flow rate of the washing liquid, etc. It is obvious that the main factor characterizing the ability of the washing liquid to water loss is the quantity the free water contained in it, the determination (allocation) of which by the considered method does not have the required accuracy. The frequency of monitoring, associated with the manual selection of washing liquid from the circulating system, equipping the device with a paper filter and manually performing other auxiliary technological operations, leads to the loss of valuable information about the dynamics contained in the washing liquid of free water, and, as a result, to problems associated with with the adoption of operational measures for the effective management of the drilling regime. With all this, this method leads to an increase in the complexity of the control and to a large investment of time in obtaining and documenting the required information.

There is also known a method that differs from the foregoing by monitoring the fluid loss of the washing fluid with automatic recording of measurement readings during drilling [3]. This method, implemented with the help of a sufficiently complex measuring device of the RPGR-10 type, with the exception of automatically periodically recording and documenting the measurement results, has all the disadvantages inherent in the above method.

Closest to the proposed one is a method for controlling the loss of washing fluid with automatic registration of measurement readings during well drilling, based on determining the rate of filtration of free water from the washing fluid into the reservoir.

The invention solves the problem of increasing the information content and reliability of monitoring the fluid loss of the washing fluid, as well as reducing the complexity and reducing the time spent on auxiliary technological operations related to the measurement process.

To achieve the technical result in the proposed method for controlling the fluid loss of the washing fluid with automatic recording of measurement readings during well drilling, based on determining the rate of filtration of free water from the washing fluid into the reservoir, when drilling the reservoir from the moment the rock-cutting tool approaches it in the circulation the well system simultaneously and continuously measure the humidity and density of the flushing fluid, according to to which the current volumetric free water content in said liquid is calculated by the formula

, $${\text{V}}_{\text{AT}}=\text{0}\text{01}\text{η}\frac{{\text{ρ}}_{\text{P}}}{{\text{ρ}}_{\text{AT}}}{\text{V}}_{\text{P}}\left(\text{one}\right)$$

,

where η is the humidity of the washing liquid;

ρ _P , ρ _B - respectively, the density of the washing liquid and water;

V _P - arbitrarily specified volume of flushing fluid,

and water loss is determined as the well deepens according to the difference in volumetric content of free water in the flushing fluid at the inlet to and from the outlet of the drilled productive formation.

Distinctive features of the proposed method for monitoring the flow of washing fluid with automatic recording of measurement data during drilling, based on determining the rate of filtration of free water from the washing fluid into the reservoir, from the above closest to it are: simultaneous and continuous measurement of humidity and density of the washing fluid in the circulation system of a well when drilling a reservoir from the moment the rock-destroying approach to it begins about the tool; calculation according to the formula (1) according to the readings of a moisture meter and a densitometer, the current volumetric content of free water in the circulating washing liquid; determination of water loss as the well deepens according to the difference in volumetric content of free water in the flushing fluid at the inlet to and from the outlet of the drilled productive formation.

The essence of the proposed method is as follows.

Before drilling, usually in the receiving tank of the mud pumps or in the outlet pipe of the sieve-hydrocyclone unit, which are integral parts of the borehole circulation system, a measuring complex is installed, which includes humidity and density sensors of the washing fluid in the circulation system. In relation to the location of the measuring complex, it can be made flowing or submersible, and the sensors used can be based on various known methods for measuring humidity and density of solutions. Depending on the technological tasks to be solved and the design features of the drilling rig, other locations of the measuring complex can be determined, unlike the aforementioned. Given that the essence of the proposed method does not change, we consider its technical implementation using the example of the installation of a measuring complex with humidity and density sensors in the outlet pipe of a hydrocyclone [3].

In the process of drilling a well during the flow of flushing fluid in the circulation system, the sensors of the measuring complex simultaneously and continuously measure the moisture and density of the specified fluid, determined by the expressions:

where η is the humidity of the washing liquid,%;

m _P , m _B - respectively, the mass of an arbitrarily specified volume of washing liquid and the mass of free water contained in the specified volume of this liquid;

ρ _P is the density of the washing fluid;

V _P - arbitrarily specified volume of flushing fluid.

Indications of humidity and density of the washing liquid in the form of sensor signals associated with expressions (2) and (3) are sent to the microprocessor processing unit (or computer), in which the mass content of free water is calculated in accordance with the formula

further, taking into account the expression m _B = ρ _B V _B (where ρ _B and V _B are the density and volumetric content of free water in an arbitrarily specified volume of washing liquid), the measurement readings determined by formula (4) are brought to the form (1), more user friendly. The readings of the density ρ _P and the volume fraction of free water V _B contained in an arbitrarily specified volume of washing liquid, brought, for example, to the value of V _P = 1 cm ³ , are displayed on the printer and indicator board.

The information obtained in this way allows, in real time, along with other controlled parameters to judge the quality of the circulating flushing fluid. When drilling a permeable object and, first of all, a productive formation from the beginning of the approach of the rock cutting tool (chisel) to it, information on the water yield of the flushing fluid is especially important. To obtain this information, before entering the bit into the roof of the reservoir, the previously calculated volumetric content of free water in the washing liquid is recorded (stored). After the bit enters the reservoir until the exit from it, the current volumetric content of free water is continued to be determined and, as the well deepens, in accordance with the expression below, the water yield of the flushing fluid is determined:

- объемное содержание свободной воды в промывочной жидкости на входе в разбуриваемый продуктивный пласт;Where $${\text{V}}_{{\text{AT}}_{\text{in}}}$$

- volumetric content of free water in the flushing fluid at the entrance to the drilled productive formation;

- текущее объемное содержание в промывочной жидкости на выходе из разбуриваемого продуктивного пласта. $${\text{V}}_{{\text{AT}}_{\text{out}}}$$

- the current volumetric content in the flushing fluid at the outlet of the drilled productive formation.

If we take into account that during drilling at the wellhead using a sieve-hydrocyclone installation, the flushing fluid is cleaned of cuttings and sand fragments, and a change in the volume content of free water in this fluid can only occur when it rises to the wellhead in the depth interval “bottom hole - casing shoe ”in the annular space between the drill string and the walls of previously exposed rocks having practically unchanged characteristics, it becomes clear that algorithm (5) can be Recognize providing a completely reliable control of the flow rate of the flushing fluid during the drilling of the reservoir. It should be noted that the above method does not exclude the possibility of exploring the well, regardless of the attachment to the reservoir. In accordance with the algorithm (5), the flow rate of the washing liquid can also be carried out by step-by-step fixing during the drilling process a number of upper (input) and lower (output) values of the volumetric content of free water both at equal and time intervals Δt determined by penetration by a bit. In this case, the rate of fluid loss of the washing liquid will be determined by the ratio ΔV _B / Δt, and a change in its sign to the opposite will indicate the influx of formation water.

The proposed method for monitoring the flow rate of flushing fluid will allow using the continuously recorded readings of density ρ _P and the volumetric content of free water V _{B to} monitor the dynamics of the composition of the flushing fluid used in the drilling process, and quickly obtain the instantaneous flow rate to solve the problems of trouble-free control of the drilling mode at high penetration quality horizons.

Information sources

1. Sereda N.G., Soloviev E.M. Drilling oil and gas wells. - M.: "Nedra", 1974, 456 s, p. 142-143.

2. "Methodology for monitoring the parameters of drilling fluids." RD 39-00147001-773-2004, p. 3.4,

3. Reference drill master. P.T. Ptichkin, V.L. Prokschits. Publishing house "Nedra", 1968, 477 p. 356-358, p. 366.

Claims (1)

A method of controlling fluid loss of a washing fluid with automatic recording of measurement readings while drilling a well, based on determining the rate of filtration of free water from the washing fluid into the reservoir, characterized in that when drilling the reservoir from the moment the rock cutting tool approaches it in the well circulation system and continuously measure the humidity and density of the washing liquid, according to the readings of which the current volumetric the free water content in the specified liquid according to the formula

where η is the humidity of the washing liquid;
ρ _P , ρ _B - respectively, the density of the washing liquid and water;
V _P - arbitrarily specified volume of flushing fluid,
and water loss is determined as the well deepens according to the difference in volumetric content of free water in the flushing fluid at the inlet to and from the outlet of the drilled productive formation.