SU1084428A1 - Method of determining absorption zone while drilling - Google Patents

Abstract

A METHOD FOR DETERMINING THE ABSORPTION ZONE IN THE DRILLING PROCESS, which includes measuring the flow rate of the washing solution at the well exit during the direct washing process and the absorption intensity corresponding to this flow, characterized in that, in order to improve the accuracy, determine the absorption zone, the process of which the flow rate of the injection fluid is changed into the well until the absorption intensity is equal to the absorption intensity during the direct flushing process, the corresponding etstvuyuschy ztomu intensity value of the solution flow rate at the well outlet before the absorption zone and determining the distance from the wellhead using the following formula: L X. BblX.rtp --- + 1: Qb (H.Obr §: where L is the depth of the well, m (L Qevx.np 6biv-obp-P & P & with washing solution at the exit of the well with - direct and reverse washings, respectively, and measured at equal values of the absorption intensity, l / min.

Description

1 The invention relates to methods for determining the location of the absorption zones of washing solutions and can be used in drilling wells with projectiles with removable core receivers such as CCK and KSSK, the drilling of which is characterized by small annular gaps. Methods are known for determining the location of absorption zones using packers. The studies using these methods were carried out by the forces of the brigade using drilling equipment and special tools. Application is indicated. The method allows to reduce the time between the occurrence of acquisitions and positioning by eliminating the time of organizing the work of the special geophysical service lj. However, the known methods reduce the technical and economic indicators of drilling due to the downtime caused by the implementation of methods. These operations should include lifting the drill string, installing the drill string on them with a special packer tool, as well as performing research during a discrete drilling of the drill string, and lifting the drill at the end of the research. This deficiency is manifested to a greater degree when drilled with projectiles with removable core receptacles, when projectile lifting is rare and the need for lifting is determined only by the resistance of the rock destructive tool. A known method for determining the absorption zone in the drilling process, includes measuring the flow rate of the washing solution at the well exit during the direct washing process and the absorption intensity 2 corresponding to this flow rate. The disadvantage of the known method lies in the low accuracy of determining the location of the absorption zone. The method allows to determine the moment of occurrence of absorption, while the location of the zone may correspond to previously drilled intervals of the well, for example, when the absorption is resumed in previously dumped zones, in violation of the integrity of the casing string Idr. The purpose of the invention is to improve the accuracy of determining the location of the absorption zone of the industrial solution. The goal is achieved by the fact that according to the method of determining the absorption zone in the drilling process, including measuring the flow rate of the washing solution at the well exit during the direct flushing process and corresponding to the flow rate of the absorption intensity, the backwash well is also performed, during which the flow rate of the injection pump is changed the solution until the absorption intensity is reached during the direct washing process, the solution flow rate at the well outlet is measured corresponding to this intensity value s and determined distance ot.ust wells D5 absorption zone with the following formula: Q Ekl V ave Qftbllr. Arr where L - well depth, m; VPS, U VALV, flow rates of the prog-suture solution at the outlet of the well for direct and reverse flushing, respectively, and measured at equal absorption intensity values, l / min. The drawing shows a flow diagram of the washing solution in the well. The drawing denotes a drill pipe string 1, a sealing device 2 (e.g., a preventer), an internal volume of 3 drill pipes, a borehole space 4, a washing fluid absorption zone 5, a direction 1, and a flow of washing fluid for direct and reverse flushing, respectively. According to the known ratios of the hydraulics of the flushing fluids, the fluid pressure in the well and the pressure in the absorbing reservoir are related to the direct flushing of the P, + E nf) H reverse flushing. + Р, - Р LРп Р, (.L-xni гдедР and bPj-pressure drops between the fluid pressure in the well and the pressure in the absorbing reservoir with direct and reverse flow, respectively; р Р - hydrostatic pressure of the washing liquid column; P. - losses pressures corresponding to hydroresistances in the annular space in the X interval during direct washing; P, are pressure losses corresponding to hydrospuns in the annular space in the interval (LX) during backwashing; PJ pressure losses corresponding to hydroelectric constants inside bu If you create direct and reverse washing modes under the condition Д Р | Pjr, taking into account that P and P-2 are equal and taking into account equal-pressure pressures, the right parts of the expressions (and (2) take the form PCOI P (Lx ) ii PV (3 Modes of pumping the wash solution in the forward and reverse directions, in which uPj bPii can be determined by measuring the wellhead information on the equality of the absorption intensities uQj and bQij, respectively, with alternate pumping in the forward and reverse directions. ,; Using the ratios of hydraulics, expression (3) can be written in the following form: (for example, and-X1-0; ,,,, where D, is the coefficient of hydroresistance in the annular space at a given speed of rotation of the projectile and the flow rate. X is the interval from the wellhead to the absorption zone; IKHPRR Flow rate of the washing solution at the well exit during direct flushing; Output of the flushing solution at the exit of the well during reverse flushing; L2 - coefficient of hydroresistance in the annular space at a certain speed of rotation of the projectile and races ode of a liquid; 8.12-10 - coefficient (D-dh). (D d,) cy, D - borehole diameter,} „- outer diameter of the boring To facilitate the practical implementation of the method, the following is admitted: the term P in expression (A) can be neglected, Since, when drilling with a removable core receiver, the pressure loss in the annular space is more than an order of magnitude greater than the loss inside the pipes, which introduces an error of less than 5%, the borehole diameter is taken to be the same throughout the well length (when drilling with removable core receiver, wells minimum and a diameter close to the diameter of the well drilling, considering this value coefficients A in both parts of equation (4) are received by the same, to determine the pressure loss in the annular space of the product 1 (. Q Y) take equal HHMk. QJ, and K. QJ, (constant value), where Lc is the coefficient of hydraulic resistance in the annular space corresponding to the flow rate at a certain rotational speed, K is a constant coefficient. Such assumptions are legitimate for the following reasons. Results of a study of pressure losses in production wells. In these lines, their dependence on the flow rate is noted, which is close to linear, and the dependence on depth is also linear. Therefore, it can be assumed that, as costs change, the product Yap Qn remains constant, and Taking into account the accepted

(4) accepts

The expression assumptions are as follows:

Lee's)

K.Q

VYU.Ovr

(5) out P | you. The ratio of the flow rate at the outlet and the well to the additional operation measured by the flow rate at the outlet of the well during backwashing characterizes the ratio of hydraulic resistances and the length of sections of the circulating system separated by the absorption zone, therefore, the proposed method can be used to refine the location of the absorption zone. The method is carried out as follows. / The well is drilled with a shell with a removable core receiver. The interval of the well is cased with pipes of a depth of 220 m. A clay fluid is used as the flushing medium. The drilling is carried out in the mode with the following parameters: load-on bottomhole kgf; Often the rotation of the projectile and c 620 rpm is the flow rate of the Q flushing solution 60 l / min At a well depth of 800 m, partial absorption of the flushing fluid was noted with a refining intensity of 4 Qoep 30 l / min, while at the well exit the solution exits with a flow rate Q Bbjx.np 30 l / min. To determine the location of the partial absorption of the proposed method, the reverse npoj (BKY) is organized. By controlling the injection flow rate Qax. OBR 3 l / mi at the entrance of Qex; gadget 43 l / min; using the absorption (6), determine the location of the absorption zone, Qebin.41 "k -" - 4-1 EXT.

(7)

235 m, taking into account information about the well design and drilling technology, it is easy to assume that the washing solution is suitable for casing (depth 220 m). The downhole flow meter confirmed that the absorption zone is at a depth of 220 m. Assumptions taken to simplify the implementation of the method introduce an error in the result of determining the location of the absorption zone, however, taking into account information about the well design and the actual technology of its drilling , plugging of well intervals, etc.) the application of the method allows specifying the location of the absorption zone with sufficient accuracy for successful elimination of the absorption. After determining the location of the absorption zone, it is isolated by pumping a plugging solution directly through the drill pipe: or using special tools. The proposed method for determining the location of the absorption zone is carried out by the drilling crew and excludes the organization time of the work of the special services. In addition, the implementation of the proposed method for determining the location of the absorption zone is carried out by the drilling crew using commercially available drilling equipment and does not require: special geophysical equipment and highly skilled specialists (determination of the location of the absorption zone by the proposed method is carried out under actual conditions of circulation of the washing fluid in the process of drilling, under actual conditions of the interaction of the circulating wash solution with the absorption zone The application of this method allows to increase the productivity of drilling operations and their technical and economic indicators due to the operational location

Claims (1)

METHOD FOR DETERMINING THE ABSORPTION ZONE IN THE DRILLING PROCESS, which includes measuring the flow rate of the flushing solution at the well outlet during direct flushing and the absorption intensity corresponding to this flow rate, characterized in that, in order to increase the accuracy and determination of the absorption zone, the wells are additionally flushed during the process which change the flow rate of the solution injected into the well to achieve an absorption intensity equal to the absorption intensity in the process of direct washing, measure accordingly this conductive solution flow rate value at the outlet hole to the absorption zone and determine the distance from the wellhead using the following formula: Q BbfX-Pr —------ + f H OUTPUT. OBr. Where b - well depth, m; QBVx.np ^{11 Q} out. or ^races ~ ^ ^{ode P} R ° "myvochnogo solution at the outlet hole when iz_ -straight and backflushing respectively, and measured at equal values of the absorption intensity l / min.