RU2164599C2 - Method of investigation of liquid-phase dynamic processes in strata with anomalously low pressure - Google Patents

Abstract

FIELD: hydrogeology. SUBSTANCE: method can be employed to control development of oil-and water- bearing strata. Indicators of several colors are used in this investigation. Indicator of each color is prepared in the form of liquid suspension of microgranules composed of mixture of polycondensated resin and organic luminescent substance. Dispersity degree of microgranules is found by proposed formula. Indicators are mixed with selected volume of stratal fluid in accordance with preset proportion. Central injection wells arranged in certain manner are selected. Prepared suspension of indicator of one color is pumped into each well. There is formula submitted to determine time after which first sample is taken from each observation well. Frequency of sampling of stratal fluid is also found by proposed formula as well as time of termination of sample taking. Concentration of indicator of each color is determined in each taken sample. Concentration of similar indicator entered face zone of stratum corresponding to it is found by proposed formula. Aggregate of values of change of concentration of indicator of each color in time in face zone of stratum is used to determine its capacitive-filtering properties and directions of liquid-phase flows. EFFECT: enhanced authenticity of investigations thanks to proper selection of properties of indicators. 1 cl, 7 dwg, 3 tbl

Description

 The invention relates to hydrogeology, namely to geofluidodynamics, and can be used to control the development of oil and aquifers.

Analysis of the current level of technology showed the following:
There is a known method of studying the movement of oil in the reservoir during the development of a reservoir, which consists in introducing into the reservoir through injection wells an indicator with a carrier (see AS No. 1017794 of June 11, 81, class E 21 B 47/00, published in OB N 18, 1983). Separate fractions of oil selected from the reservoir are used as a carrier, tritium or fluorine as an indicator.

The disadvantage of this method is to obtain inaccurate data on the dynamics of liquid-phase processes, especially when implementing the method in water-saturated reservoirs, since oil, having its physico-chemical properties different from water, moves in the reservoir at a speed different from the rate of oil filtration, and only when exceeding a certain value of saturation. In addition, during the movement of oil in the reservoir, composed in especially terrigenous reservoirs, the fractional and total oil composition changes as a result of interaction with the rocks;
as a prototype, a method for studying the movement of oil in the reservoir during the development of a reservoir is taken, which consists in simultaneously injecting several different indicators into several injection wells together with a carrier, namely industrial water, with one indicator being injected into each of the injection wells, and in the flows leaving the production wells, the content of all used indicators is separately recorded and, according to the time of their passage, they monitor the movement of PTI in water (see. Wagner OR Journal of petroleum technology, 1977, N 11, p. 1410-1416).

 The disadvantage of this method is to obtain false data on the dynamics of liquid-phase processes. The introduction of the indicator in the carrier, which is used as industrial water, violates the natural dynamics of liquid-phase formation flows, and can also lead to swelling of clay minerals in terrigenous reservoirs and a decrease in permeability. In addition, for the registration of various indicators, different recording equipment is required (ionizing radiation counters, facilities for chemical analysis, photo-calorimeters, etc.). It is very difficult to compare the results obtained when using indicators of various types, since each indicator is characterized by individual migration parameters and processes of interaction with the liquid and rock, which determine the individuality of losses and differences in the speeds of movement of the indicator and the carrier.

The technical result that can be obtained by implementing the present invention is as follows: the reliability of studies is increased by choosing the properties of the indicator, which allows to obtain an adequate model that reflects the natural dynamics of liquid-phase reservoir flows under the conditions of the AIP;
the range of technology application is expanding, as an indicator with the claimed properties can be introduced with any liquid carrier.

где h_ин ^max - длина интервала перфорации фильтра наблюдательной скважины, выбранная из условия максимальности из ряда наблюдательных скважин, или мощность пласта, не обсаженного эксплуатационной колонной в наблюдательной скважине, выбранная из условия максимальности из ряда наблюдательных скважин, м;
m - коэффициент открытой пористости, д.ед.;
V_пл - истинная скорость потока подземной жидкости, м/мин;
γ_ж - плотность пластовой жидкости, кг/м³;
d_скв ^min - внутренний диаметр наблюдательной скважины, выбранный из условия минимальности из ряда наблюдательных скважин, м;
g - ускорение свободного падения, м/с²;
Re - число Рейнольдса для подземных жидкостей;
γ_мг - плотность микрогранул индикатора каждого цвета, кг/м³;
d_м - диаметр микрогранул индикатора каждого цвета, м;
d_пор - минимальный размер поровых каналов пород-коллекторов, м;
h_св - толщина слоя связанной жидкости, м,
смешивают с отобранным объемом пластовой жидкости в соотношении об. частей, равном 0,0005 : 0,001 - 1 соответственно, а из множества нагнетательных скважин выбирают центральные нагнетательные скважины, расположенные в одном или нескольких горизонтах исходя из системы расположения наблюдательных скважин по площади, и в каждую из них закачивают полученную взвесь индикатора одного цвета в пластовой жидкости, определяют временной интервал, через который отбирают первую пробу с уровня скважинной жидкости из каждых наблюдательных скважин, расположенных в одном или нескольких горизонтах, по формуле
t_1j-к = bl_i-к/V_пл + t_всплj,
где t_1j-к - временной интервал, через который отбирают первую пробу с уровня скважинной жидкости из j-й наблюдательной скважины, мин;
в - коэффициент, учитывающий макродисперсию в "лобной" части волны индикатора и ошибки определения истинной скорости потока подземной жидкости, д.ед.;
l_j-к - расстояние от середины интервала перфорации к-й центральной нагнетательной скважины до середины интервала перфорации фильтра или середины пласта-коллектора, не обсаженного эксплуатационной колонной, в j-й наблюдательной скважине, м;
t_вспл.j - время, необходимое для всплытия микрогранул индикатора от нижних дыр интервала перфорации фильтра или подошвы пласта-коллектора, не обсаженного эксплуатационной колонной, до уровня жидкости в j-й наблюдательной скважине, мин, равное

где h_j - высота пластовой жидкости в j-й наблюдательной скважине от нижних дыр интервала перфорации фильтра или подошвы пласта-коллектора, не обсаженного эксплуатационной колонной, j-й наблюдательной скважины, м,
а для каждой наблюдательной скважины определяют частоту отбора проб пластовой жидкости по выражению
Δt_j-к = (4V_з.к/mh_з.кπ)^0,5(6V_пл)^-1+t_вспл.j,
где Δ t_j-к - временной интервал, через который отбирают каждую последующую пробу после первой, с уровня скважинной жидкости из j-й наблюдательной скважины, мин;
V_з.к - объем закачки индикатора к-го цвета в к-ю центральную нагнетательную скважину, м³;
h_з.к - длина интервала перфорации в к-й центральной нагнетательной скважине, через которую введен в пласт индикатор к-го цвета, м,
а время окончания отбора проб для каждой наблюдательной скважины находят по формуле
t_Σj-к = в′l_j-к/V_пл+t_вспл.j+(4V_з.кπ)^0,5V $\genfrac{}{}{0ex}{}{\text{-1}}{\text{пл}}$ ,
где t_Σj-к - время окончания отбора проб для j-той наблюдательной скважины, мин;
в' - коэффициент, учитывающий макродисперсию в "хвостовой" части волны концентрации индикатора и ошибки определения истинной скорости потока подземных жидкостей, д.ед.,
причем в каждой отобранной пробе определяют концентрацию индикатора каждого цвета, находят соответствующую ей концентрацию аналогичного индикатора, ранее поступившего в призабойную зону пласта, по формуле

где C_ij(t_ij-к) - концентрация в призабойной зоне индикатора к-го цвета в i-й пробе, отобранной с уровня скважинной жидкости из j-й наблюдательной скважины, микрогранулы/м³, причем t_ij-к определяют из выражения,
где C_ij(t_ij-к) - концентрация в призабойной зоне индикатора к-го цвета в i-й пробе, отобранной с уровня скважинной жидкости из j-й наблюдательной скважины, микрогранулы/м³, причем t_ij-к определяют из выражения
t_ij-к = t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-к-t_вспл.j,
где t_ij-к - время поступления индикатора к-го цвета в призабойную зону, соответствующее времени отбора i-й пробы с уровня скважинной жидкости j-й наблюдательной скважины, мин;
t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-к - время отбора i-й пробы с уровня скважинной жидкости в j-й наблюдательной скважине, мин;
h_уст - высота устройства для отбора проб скважинной жидкости с уровня j-й наблюдательной скважины, м;
C $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-к(t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-к) - концентрация индикатора к-го цвета в i-й пробе, отобранной с уровня скважинной жидкости из j-й наблюдательной скважины, микрогранулы/м³;
C $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _-lj-к(t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _-lj-к) - концентрация индикатора к-го цвета в i-1-й (предыдущей) пробе, отобранной с уровня скважинной жидкости из j-й наблюдательной скважины, микрогранулы/м³;
d_уст - внутренний диаметр устройства для отбора проб скважинной жидкости с уровня j-й наблюдательной скважины, м;
V $\genfrac{}{}{0ex}{}{\text{*}}{\text{п}}$ _лj-к - истинная скорость потока пластовой жидкости по направлению от к-й нагнетательной скважины к j-й наблюдательной скважине, м/мин, определяемая из выражения
V $\genfrac{}{}{0ex}{}{\text{*}}{\text{п}}$ _лj-к = l_j-кm^-1(t_l $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-к-t_вспл.j)^-1
где t $\genfrac{}{}{0ex}{}{\text{*}}{\text{l}}$ _ij-к - время отбора первой пробы с уровня скважинной жидкости в j-й наблюдательной скважины, в которой C $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-к(t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-к) ≠ 0, мин;
h_ин.j - длина интервала перфорации фильтра или мощность пласта-коллектора, не обсаженного эксплуатационной колонной j-й наблюдательной скважины, м;
t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _-lj-к - время отбора i-1-й (предыдущей) пробы, отобранной с уровня скважинной жидкости в j-й наблюдательной скважине, мин,
и далее по найденному множеству значений изменения концентрации индикатора каждого цвета во времени в призабойной зоне пласта определяют его емкостно-фильтрационные свойства и направления жидкофазных потоков.The technical result is achieved using a known research method based on the introduction of indicators in a liquid carrier into the formation, each of which is pumped into an appropriate injection well, formation fluid sampling with subsequent interpretation of the results in time, in which an indicator of each color is obtained in the form of a liquid suspension of microgranules consisting of a mixture of polycondensation resin and an organic luminescent substance with a degree of dispersion selected from the inequality

where h _in ^max is the length of the filter perforation interval of the observation well, selected from the maximum condition from a number of observation wells, or the thickness of the reservoir not cased by the production string in the observation well, selected from the maximum condition from a series of observation wells, m;
m is the coefficient of open porosity, d.ed .;
V _PL - the true flow rate of the underground fluid, m / min;
γ _W - the density of the reservoir fluid, kg / m ³ ;
d _well ^min - the internal diameter of the observation well, selected from the minimum condition from a number of observation wells, m;
g is the acceleration of gravity, m / s ² ;
Re is the Reynolds number for underground fluids;
γ _mg — density of indicator microgranules of each color, kg / m ³ ;
d _m - the diameter of the microspheres of the indicator of each color, m;
d _then - the minimum size of the pore channels of the reservoir rocks, m;
h _St - the thickness of the layer of bound fluid, m,
mixed with the selected volume of reservoir fluid in a ratio of about. parts equal to 0.0005: 0.001 - 1, respectively, and from the number of injection wells, central injection wells are located located in one or more horizons based on the area of the observation wells, and the suspension of the same color indicator is pumped into each of them in the reservoir fluid, determine the time interval through which the first sample is taken from the level of the wellbore fluid from each observation well located in one or more horizons, according to the formula
t _1j-k = bl _i-k / V _pl + t _pop-up ,
where t _1j-k - the time interval through which the first sample is taken from the level of the wellbore fluid from the j-th observation well, min;
in - coefficient taking into account macrodispersion in the "frontal" part of the indicator wave and errors in determining the true velocity of the underground fluid flow, d.ed .;
l _j-k - the distance from the middle of the perforation interval of the k-th central injection well to the middle of the interval of perforation of the filter or the middle of the reservoir, not cased by the production string, in the j-th observation well, m;
t _pop.j - time required for the indicator microgranules to _emerge from the lower holes of the filter perforation interval or the bottom of the reservoir, not cased by the production string, to the liquid level in the j-th observation well, min, equal

where h _j is the height of the reservoir fluid in the j-th observation well from the lower holes of the perforation interval of the filter or the bottom of the reservoir, not cased by production casing, j-th observation well, m,
and for each observation well, the sampling frequency of the reservoir fluid is determined by the expression
Δt _j-k = (4V _z.k / mh _z.k π) ^0.5 (6V _pl ) ^-1 + t _pop.j ,
where Δ t _j-k - the time interval through which each subsequent sample is taken after the first, from the level of the wellbore fluid from the j-th observation well, min;
V _s.k - the indicator injection volume of the k-th color in the k-th central injection well, m ³ ;
h _z.k - the length of the perforation interval in the k-th central injection well, through which the indicator of the k-th color is introduced into the formation, m,
and the sampling end time for each observation well is found by the formula
t _Σj-k = v′l _j-k / V _pl + t _{float j} + (4V _З.к π) ^0.5 V $\genfrac{}{}{0ex}{}{\text{-1}}{\text{pl}}$ ,
where t _Σj-k is the sampling completion time for the j-th observation well, min;
in '- coefficient taking into account macrodispersion in the "tail" part of the wave concentration of the indicator and errors in determining the true flow rate of underground liquids, unit
moreover, in each sample taken, the indicator concentration of each color is determined, the corresponding indicator concentration of a similar indicator, previously received in the bottomhole formation zone, is found by the formula

where C _ij (t _ij-k ) is the concentration in the bottom-hole zone of the indicator of the k-th color in the i-th sample, taken from the level of the wellbore fluid from the j-th observation well, microgranules / m ³ , and t _ij-k is determined from the expression ,
where C _ij (t _ij-k ) is the concentration in the bottom-hole zone of the indicator of the k-th color in the i-th sample, taken from the level of the wellbore fluid from the j-th observation well, microgranules / m ³ , and t _ij-k is determined from the expression
t _ij-k = t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-to -t _pop.j ,
where t _ij-k is the arrival time of the indicator of the k-th color in the bottomhole zone, corresponding to the time of sampling of the i-th sample from the level of the borehole fluid of the j-th observation well, min;
t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-k — time of sampling of the i-th sample from the level of the borehole fluid in the j-th observation well, min;
h _mouth - the height of the device for sampling borehole fluid from the level of the j-th observation well, m;
C $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _jk (t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-k ) is the concentration of the indicator of the k-th color in the i-th sample taken from the level of the wellbore fluid from the j-th observation well, microgranules / m ³ ;
C $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _-lj-k (t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _-lj-k ) is the concentration of the indicator of the k-th color in the i-1st (previous) sample, taken from the level of the borehole fluid from the j-th observation well, microgranules / m ³ ;
d _mouth - the inner diameter of the device for sampling well fluid from the level of the j-th observation well, m;
V $\genfrac{}{}{0ex}{}{\text{*}}{\text{P}}$ _lj-k - the true flow rate of the reservoir fluid in the direction from the k-th injection well to the j-th observation well, m / min, determined from the expression
V $\genfrac{}{}{0ex}{}{\text{*}}{\text{P}}$ _lj-k = l _j-k m ^-1 (t _l $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-to -t _pop.j ) ^-1
where t $\genfrac{}{}{0ex}{}{\text{*}}{\text{l}}$ _ij-k - time of the first sampling from the level of the borehole fluid in the j-th observation well, in which C $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _jk (t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-k ) ≠ 0, min;
h _in.j is the length of the filter perforation interval or the thickness of the reservoir, not cased by the production casing of the j-th observation well, m;
t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _-lj-k is the sampling time of the i-1st (previous) sample taken from the level of the borehole fluid in the j-th observation well, min,
and then, by the found set of values of the change in the concentration of the indicator of each color over time in the bottom-hole zone of the formation, its capacitive-filtration properties and the directions of liquid-phase flows are determined.

The blue indicator uses an organic luminescent substance based on dixanthylene, general formula C ₂₆ H ₁₆ O ₂ according to TU 6-09-1964-77, the green indicator uses fluorescein (resorcinophthalein), the general formula C ₂₀ H ₁₂ O ₅ according to TU 6-09-2464-77 (TU 7P-35-72), in the yellow indicator - rhodamine F according to TU 6-09-2463-77, in the red indicator - rhodamine 200B, of the general formula C ₂₇ H ₂₉ N ₂ NaO ₇ S ₂ , according to TU 6-09-07-67-73. As the polycondensation resin, melamine-formaldehyde resin is used: K-79-79 melalit (VTU MHP M-733-56) or VEI-11 melamine-urea-formaldehyde resin (VTU 4107-53 and TU MHP M-692-56) .

 Known methods for researching wells, which include injecting into the well a luminescent solution, mainly fluorescein, followed by measuring the intensity of luminescence along the wellbore in order to increase the reliability of detection of asbestos cores (see V. Ferronsky et al. Radioisotope research methods in engineering geology and hydrology . - M .: Atomizdat, 1977, p. 168; A.S. N 987554 dated July 28, 81 according to class G 01 V 9/00, published in OB N 1, 1983), the technical solutions indicated are of particular interest. in A.S. N 1639123, publ. 02.28.94 and N 1473405 publ. 01/30/94. According to available sources of information (patent documentation and scientific and technical literature), no methods for studying liquid-phase dynamic processes in formations with abnormally low pressure according to the claimed technical result, which coincide with the distinguishing features of the present invention, have been identified. The claimed technical solution has an inventive step.

 The use of several colors of the indicator allows simultaneous injection of the indicator into different wells and unambiguously determines in quantitative terms from which central injection well the indicator has migrated. Using an indicator of only one color is impossible (unpromising), because it leads to ambiguity in the final interpretative results. The injection of a single color indicator into each central injection well is due to the largest coverage of the well stock under study, which ultimately allows a more adequate areal picture of the liquid-phase migration processes in the formation with an abnormally low pressure.

раз) за счет увеличения эффективного сечения фильтрации и затухают микропульсации скорости. В таких условиях индикатор становится седиментационно неустойчивым и за счет меньшей плотности и незначительного диаметра микрогранулы всплывают вверх, накапливаясь на уровне жидкости.An observation well plays the role of not only a fluid sampling point, but also a “trap” for a finely dispersed indicator consisting of microgranules of a given color. When migrating in the reservoir, the indicator according to Chen's equation (see Monin AS, Yaglom AM Statistical hydromechanics. Turbulence mechanics. - M .: Nedra, 1965, - 639 s.) Is in sedimentation stability, although characterized by a lower density of microgranules in comparison with the reservoir fluid. This is ensured by micropulsations both in time and in the space of the velocity of the underground stream. When an underground stream crosses a wellbore, its speed decreases sharply (in

times) by increasing the effective cross-section of the filtration and attenuating the micropulsation rate. Under such conditions, the indicator becomes sedimentationally unstable and, due to its lower density and insignificant diameter, microgranules float upward, accumulating at the liquid level.

The degree of dispersion of the indicator microgranules is selected in such a way that the time for the microgranules to emerge in the interval of the perforation filter of the observation well or in the interval of the reservoir not cased by the production string, t _pop ^max , determined by the Stokes equation, is less than or equal to the time required for the underground fluid to cross the barrel wells, t _pp , i.e.

При получении микрогранул индикатора по размерам более установленной максимальной нормы часть индикатора уйдет вместе с потоком пластовой жидкости из ствола наблюдательной скважины, что приведет к искажению значений исследования.t _float ^max ≅ t _pp or

Upon receipt of indicator microbeads in sizes larger than the established maximum norm, a part of the indicator will go away together with the flow of formation fluid from the observation well bore, which will lead to a distortion of the study values.

 Upon receipt of indicator microbeads in sizes less than the established minimum norm, a technical result is possible (i.e., the microbeads are fully surfaced), but additional energy and time costs are incurred to obtain indicator microbeads, which is not economically feasible.

 Polycondensation resin, which is the main component of indicator microgranules, is characterized by inertness with respect to formation fluids (water, oil, condensate) and rocks, i.e. does not enter into reactions with them, which may entail a change in its properties.

 Mixing indicator with formation fluid in a ratio of vol. parts equal to 0,0004: 1, impractical due to the receipt of a large degree of dilution, which will lead to insensitivity of the method.

 Mixing indicator with formation fluid in a ratio of vol. parts equal to 0.002 - 1 will lead to coagulation of the microgranules, their agglomeration and precipitation with loss of degree of dispersion.

 The start time of the first sampling characterizes the minimum time interval through which the “frontal” part of the concentration wave of the indicator can come. When choosing a time interval less than the proposed calculation formula, obviously "zero" values of the indicator concentration are obtained. In the above examples of the method, obtaining "zero" concentrations of the indicator in the first samples indicates a variation in the area of the rate of migration of formation fluids and does not affect the universality of this formula.

 The frequency of sampling reservoir fluid is determined by an expression that takes into account the concentration wavelength of the indicator and satisfies Kotelnikov’s inequality (see Kanasevich ER, Analysis of Time Sequences in Geophysics. - M .: Nedra, 1985, - 300 p.) On the number of points on concentration wave necessary for its sufficient description. The formation fluid sampling frequency thus determined ensures the optimal study of liquid-phase dynamic processes in formations with abnormally low pressure.

 When the sampling frequency is lower than the proposed calculation, an incomplete description of the concentration wave is obtained with the loss of one of its parts, which will lead to a distortion of the obtained values of capacitance-filtration properties. The sampling frequency, which is higher than the proposed estimate, is not economically feasible.

 The presented formula for determining the sampling time fully characterizes the concentration wave of the indicator recorded in each observation well. The maximum transcendental values of the calculated value will only lead to the "zero" results.

Recalculation of the concentration of a similar indicator, which had previously entered the bottomhole formation zone, through the concentration determined in the fluid sample taken from the level of the j-th observation well, allows to increase the reliability of studies due to the fact that:
- no distortion is introduced into the underground fluid flow in the reservoir with an abnormally low reservoir pressure due to the presence of a device for sampling fluid in the interval of filter perforation or reservoir thickness not cased by the production string;
- the passage of the concentration wave (or part thereof) through the cross section of the wellbore is not allowed, which is especially important for deep wells with a high column of fluid in the wellbore, since under such conditions considerable time is spent on lowering the device for sampling fluid into the perforation zone and its subsequent rise;
- since the observation well is used as a “trap” for this type of indicator, the method is applicable for large dilution values (up to 10 ¹³ times) of the starting portions, i.e. in its sensitivity, it approaches methods in which radioactive elements are used as an indicator.

где Q_пл - объем пластовой жидкости, прошедшей через ствол j-й наблюдательной скважины за отрезок времени между ближайшими отборами проб, м³;
S_ф - фактическая площадь половины поверхности скважины в интервале перфорации фильтра или в интервале пласта, не обсаженного эксплуатационной колонны, м²,
из которого выделяется индикатор, количество которого составит

где M_ij-к - количество индикатора, выделившегося из Q_пл, микрогранулы.During the time interval between the nearest sampling through the j-th observation well at the time t _{ij-k, the} volume of reservoir fluid equal to

where Q _PL - the volume of reservoir fluid that passed through the barrel of the j-th observation well for the length of time between the nearest sampling, m ³ ;
S _f - the actual area of half the surface of the well in the interval of perforation of the filter or in the interval of the reservoir, not cased production casing, m ² ,
from which an indicator stands out, the amount of which will be

where M _ij-k - the amount of indicator released from Q _PL microgranules.

Приравняв два последних равенства, найдем концентрацию индикатора, C_ij, в подземном потоке на момент времени t_ij-к

В окончательном виде, учтя, что

получим формулу (1).For the same period of time at time t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-k = t _ij-k + t _popj at the level of the well fluid, the total number of indicator will change by

Equating the last two equalities, we find the concentration of the indicator, C _ij , in the underground stream at time t _ij-к

In final form, considering that

we obtain the formula (1).

 The determination of capacitance-filtration parameters is carried out according to well-known methods of processing the results of indicator studies of liquid-phase dynamic processes in the reservoirs (see, for example, L. Lukler, V.M. Shestakov, Modeling groundwater migration. - M .: Nedra, 1986, - 208 p. )

 In more detail, the essence of the claimed invention is described by the following example.

Example
1. Preparation of indicator microspheres
Polycondensation resin: melamine-formaldehyde resin or melamine-urea-formaldehyde resin (the composition is identical) is mixed with acetone and an organic luminescent substance: fluorescein (green indicator) or rhodamine B (red indicator, you can mix with other indicators: blue and yellow. indicators of the colors of the claimed technology is identical) in the ratio of wt. hours, equal to 1: 1: 0.1, respectively, until a homogeneous mass is formed, which cures within 24 hours. The resulting solid mass is ground in a ball mill (LE-101.1 Hungary) and sieved to a fraction of not more than 2 mm. The powder is mixed with solutions of ammonia and anionic surfactant brand Crystal in the ratio of wt. hours equal to 1: 0.6: 0.05, respectively. Next, grinding is done on a ball mill (LE-101.1 Hungary) to the calculated degree of dispersion (see below).

In FIG. 1 is a graph of the dispersion of the indicator microgranules from the grinding time, approximated by the expression
t _pom = -5.7998ln (d _mg ) - 35.853,
where t _pom is the grinding time of the polycondensation resin in a ball mill, necessary to achieve the dispersion of microspheres (d _mg ), h

The average density of indicator microgranules, γ _mg , is 800 kg / m ³ . The shape of the microgranules is close to spherical.

2. The study of liquid-phase dynamic processes in formations with abnormally low pressure
The studies were conducted on the state farm area of the Orenburg region in the super-productive stratum (terrigenous strata of rocks lying above the underground gas storage) in layers II and IV.

Collector rocks of formations II and IV are represented by sand;
open porosity coefficient, m, 0.15;
formation water related to the sodium chloride type, have a density, γ _W , kg / m ³ , 1008;
true groundwater flow rate, V _pl (according to hydrodynamic studies), m / min, 0.006; m / s, 0.0001;
the minimum size of the pore channels of the sands of the II and IV formations, d _pores (according to the results of core analysis), microns, 15;
the thickness of the layer of bound water, h _St , microns, 0.25;
maximum length of the filter perforation interval or reservoir thickness, uncased production casing, observation wells, h _in ^max , m, 15;
minimum internal diameter of observation wells, d _well ^min , mm, 152.

3,2·10^-6 < d_мг < 14,5·10^-6
и готовят индикатор, диаметр микрогранул которого составляет 5·10^-6 м.For these conditions, the diameter of the indicator microgranules of any color is chosen from the inequality

3.2 · 10 ^-6 <d _mg <14.5 · 10 ^-6
and prepare an indicator, the diameter of the microgranules of which is 5 · 10 ^-6 m

35 ч
Далее суспензию индикатора в количестве 0,007 м³ смешивают с 7 м³ пластовой воды, осуществляя соотношение об. ч. , равное 0,001 - 1 соответственно.Why carry out grinding for a time equal to
t _pom = -5.7998 (5 · 10 ^-6 ) -35.853 = 34.99

35 h
Next, a suspension of the indicator in an amount of 0.007 m ^{3 is} mixed with 7 m ^{3 of} produced water, realizing a ratio of vol. hours equal to 0.001 - 1, respectively.

 Based on the four-point non-uniform arrangement of the observation wells by area, two central injection wells located in two horizons are selected from the set of injection wells: well N 2K - formation II (see Fig. 2, which shows the layout of the central injection and observation wells , as well as a diagram of the directions of the movement of liquid-phase flows over the area of formation II) and well N 7КР - formation IV (see Fig. 3, which shows the layout of the central injection and wells, as well as a diagram of the directions of movement of liquid-phase flows over the area of the IV layer).

Using a cement mixing unit CA-320M, the obtained suspension of a red indicator (rhodamine 200B, color code, k-1) with formation fluid with a volume of 7.007 m ³ through a central injection well N 2K (perforation interval 84-91 m) is pumped into the second formation. The starting concentration of the indicator is 10 ¹³ microgranules / m ³ .

Using CA-320M, the obtained suspension of the green indicator (fluorescein, color code, k-2) and formation fluid with a volume of 7.007 m ^{3 is} pumped through a central injection well N 7КР (perforation interval 420-427 m) into reservoir IV. The starting concentration of the indicator is 10 ¹³ microgranules / m ³ .

 Water samples are taken from the level of the wellbore fluid using the GGP-20 borehole from observation wells: wells N 1, 2, 3, 4 — reservoir II, wells N 5, 6, 7, 8 — reservoir IV.

 For convenience, information and calculated data for each observation well of 2 layers are presented in table No. 1.

 Illustration of specific calculations for well N 1.

Первый отбор пробы воды с уровня в скважине осуществляют через 4664 мин после запуска взвеси индикатора красного цвета в скважину N 2K.The time interval through which the first sample is taken from the level of the borehole fluid is determined

The first sampling of water from the level in the well is carried out after 4664 min after the suspension of the red indicator suspension in well N 2K.

Отбор каждой последующей пробы воды с уровня скважинной жидкости осуществляют через каждые 578 мин.Determine the frequency of formation fluid sampling

Each subsequent water sample is taken from the level of the well fluid every 578 minutes.

Последняя проба воды с уровня скважинной жидкости будет отобрана через 15149 мин после запуска индикатора красного цвета в скважину N 2K.Determine the end time of water sampling from the level of the well fluid

The last water sample from the borehole fluid level will be taken 15149 min after the start of the red indicator in well N 2K.

 In selected water samples, the indicator content is determined by filtering the sample through a fine-porous Vladipor filter with a pore diameter of 0.4 μm. On a fine-porous filter, the microgranules of the indicator of each color are quantified using a Lumam-P2 luminescent microscope.

 The indicator is identified by five parameters: 1) the color of the microgranules, 2) the shape of the microgranules, 3) the nature of the surface of the microgranules, 4) the intensity of the glow, 5) the size of the microgranules. In the most difficult cases, quantitative fluorimetry is used, which is realized using a fluorescence-microscopic fit FMEL-1A, while an FEU-79 photomultiplier with a set of light filters SS 15, KS 11, OS 11, NS 10, ZS 12, ZS 1, is used as a spectrum analyzer. UFS 6-3, UFS 6-5, FS 1-1, FS 1-2, FS 1-4, FS 1-6, SS 15-2, SS 15-4, SZS 24-4, SZS 21-2. A SVDSh-250 mercury lamp is used as a source of ultraviolet radiation.

 In well N 1, 20 water samples were taken from the level of the well fluid. The results of the determination of the red indicator in these samples are presented in table No. 2.

According to the values of the concentrations of the red indicator in water samples taken from the level of the wellbore fluid, the corresponding concentrations of a similar indicator that had previously entered the bottomhole formation zone were determined. For convenience, information on the concentration of the red indicator that entered the bottomhole zone of the well N 1 is also presented in table N 2 and in FIG. 4 (in Fig. 4 shows a graph of the concentration of the red indicator in reservoir conditions in the bottomhole zone of the observation well N 1 from time to time). The dilution ratio is 1.02 · 10 ⁹ . Studies of wells N 2, 3, 4 showed the absence of a red indicator for the estimated time in all samples taken from the level of the well fluid.

 Illustration of specific calculations for well N 7.

 The time interval through which the first sample is taken from the level of the well fluid is determined.

Первый отбор пробы воды с уровня в скважине осуществляют через 8177 мин после запуска взвеси индикатора зеленого цвета в скважину N 7КР.

The first sampling of water from a level in the well is carried out 8177 minutes after the suspension of the green indicator is launched into well N 7КР.

Отбор каждой последующей пробы воды с уровня скважинной жидкости осуществляют через каждые 1175 мин.Determine the frequency of formation fluid sampling

Each subsequent water sample is taken from the level of the well fluid every 1175 minutes.

Последняя проба воды с уровня скважинной жидкости будет отобрана через 25663 мин после запуска индикатора зеленого цвета в скважину N 7КР.Determine the end time of water sampling from the level of the well fluid

The last water sample from the level of the borehole fluid will be taken 25663 minutes after the start of the green indicator in well N 7КР.

 In well N 7, 14 water samples were taken from the level of the well fluid.

The results of determining the green indicator in these samples are presented in Table No. 3. Using the values of the green indicator concentrations in the water samples taken from the level, the corresponding concentrations of a similar indicator that had previously entered the bottom-hole zone of well N 7 were determined (see also table N 3). The dilution ratio is 1.46 · 10 ⁹ . Studies of wells N 5, 6, 8 showed the absence of a green indicator for the estimated time in all samples taken from the level of the well fluid.

Первый отбор пробы воды с уровня в скважине осуществляют через 39760 мин после запуска взвеси индикатора красного цвета в скважину N 2К.Interstratal liquid-phase dynamic processes
Illustration of specific calculations for well N 7
The time interval through which the first sample is taken from the level of the well fluid of the second series of water sampling for the analysis of the red indicator is determined

The first sampling of water from a level in the well is carried out 39760 minutes after the suspension of the red indicator in the well N 2K is started.

Отбор каждой последующей пробы воды с уровня скважинной жидкости осуществляют через каждые 1175 мин.Determine the frequency of formation fluid sampling

Each subsequent water sample is taken from the level of the well fluid every 1175 minutes.

 Determine the end time of water sampling from the level of the well fluid.

Последняя проба (вторая серия) воды с уровня скважинной жидкости будет отобрана через 133046 мин после запуска индикатора красного цвета в скважину N 2К.

The last sample (second series) of water from the borehole fluid level will be taken 133046 min after the start of the red indicator in well N 2K.

 In the well, 80 water samples were taken from the level of the well fluid.

 In FIG. 5 is a graph of the concentration of the red indicator in samples taken from the level of the wellbore fluid, well N 7 versus the time since it was launched into well N 2K. Based on the values of the concentrations of the red indicator in water samples taken from the level, the corresponding concentrations of a similar indicator (red), previously received in the bottomhole zone of well N 7, were determined.

In FIG. 6 is a graph of the concentration of the red indicator under reservoir conditions in the bottomhole zone of well N 7 versus time since it was launched into well N 2K. The dilution ratio is 1.18 · 10 ¹¹ .

 In observation wells N 1, 2, 3, 4, which opened the II stratum, in the water samples, a green indicator, pumped into the well N 7КР in the IV stratum, is not installed. This indicates the absence of water flows from the IV layer to the II layer of the suprasalt complex of the State Farm Square.

 The red indicator, pumped into reservoir II through well No. 2K, was recorded only in water samples from observation well No. 7, which opened reservoir IV. In water samples taken from the level of observation wells N 5,6,8 (reservoir IV), a red indicator is not installed. This indicates interstratal flows from layer II to IV in the direction from the central injection well N 2K to the observation well N 7, probably along man-made migration routes.

The most characteristic parameters of the reservoir properties of the reservoirs are permeability and the true flow rate of the underground fluid. To determine them by a known method (indicated above in the "Summary of the Invention" section), the entire set of indicator concentrations of each color in the bottomhole zone is used depending on time. In the direction from well N 2K to well N 1 V $\genfrac{}{}{0ex}{}{\text{*}}{\text{1}}$ _-1 will be 0.006088 m / min, and the average permeability is 560 · 10 ^-15 m ² ; in the direction from well N 7КР to well N 7 V $\genfrac{}{}{0ex}{}{\text{*}}{\text{7}}$ _-2 will be 0.006014 m / min, and the average permeability is 426 · 10 ^-15 m ² ; in the direction from well N 2K to well N 7 V $\genfrac{}{}{0ex}{}{\text{*}}{\text{7}}$ _-1 will be 0.005202 m / min, and the average permeability is 38 · 10 ^-15 m ² .

With the dilutions given in the example of the implementation of the proposed method (~ 10 ⁹ times), the vast majority of indicators cannot be recorded in liquid samples, which is due to the sensitivity limit of the recording equipment and determination methods. Most indicators (the chemical and biological groups represented in the prototype) can be determined in liquid samples with dilutions of only about 10 ⁶ - 10 ⁷ times. Thus, the known method (prototype) of studying liquid-phase flows in the examples given would give “zero” C _ij-k (t _ij-k ), i.e. wrong conclusion about the absence of flows between wells NN 2K and 1, 7KP and 7, 7KP and 1.

 In the claimed technical solution, the observation well is used not only as a structure in which fluid samples are taken, and as a "trap", but also as an "amplifier" of the indicator transmission signal in the bottomhole zone with a gain proportional to the flow rate of the underground fluid through the wellbore.

 A device for taking deep samples of formation fluid from a perforation interval when implementing a known method, for example, a PDM-3M flow-through depth sampler, introduces disturbance into the formation fluid flow migrating across the wellbore up to 8-10%, which leads to errors in determining the reservoir filtration parameters of reservoir rocks according to indicator studies reaching 10-15% (see Akulinchev B.P. Study of ways to increase the information content of hydrogeological data from testing deep wells for production petrogas and searches for oil and gas deposits (for example Ciscaucasia) / Dissertation for the degree of KG -m.n. - Stavropol: SevKavNIIgaz, 1982 - 152)..

 In addition, omissions of a part of the indicator’s concentration wave during the implementation of the known method are caused by significant time costs required for lowering the device for selecting reservoir fluid from the interval of filter perforation in wells with a high fluid column in the well and subsequent lifting of this device to the surface, which can lead to significant errors in determining first the concentration of the indicator in the bottomhole zone, and then to the errors calculated by their values of capacitive-filtration steam meters of reservoirs. This in the known method is achieved by sampling formation fluid on the surface during continuous pumping from an observation well, which leads to disruption of natural liquid-phase migration flows and poses the problem of disposal of the selected formation fluid.

For example, in FIG. 4, the dashed line shows the concentration wave of the indicator, characterizing the implementation of the known method (without taking into account the influence of the device for sampling liquid on the results of indicator studies) under the specific conditions of the state farm area when using isotopes of hydrogen and oxygen, which are the most efficient (informative) at large dilutions exceeding 10 ⁶ - 10 ⁷ times. Comparing the curves of the concentration waves of the indicators obtained during the implementation of the proposed and known methods, the following can be noted:
- the concentration wave of the indicator of the known method is less differentiated, which is characterized by displacement and "erosion" of the maximum of this wave relative to the maximum of the concentration wave according to the proposed method;
- the concentration wave of the indicator of the known method is characterized by a height less than 22.2 times the height of the concentration wave of the indicator of the indicator of the proposed method.

 Thus, certain capacitance-filtration properties of reservoirs by a known method when implemented in formations with abnormally low reservoir pressure contain a significant percentage of error.

Claims (2)

1. A method for studying liquid-phase dynamic processes in formations with an abnormally low pressure, based on the introduction of indicators in the liquid carrier, each of which is injected into the corresponding injection well, sampling the formation fluid with subsequent interpretation of the results in time, characterized in that the indicators are used several colors, get an indicator of each color in the form of a liquid suspension of microspheres, consisting of a mixture of polycondensation resin and an organic luminescent substance with degree of dispersion, selected from the inequality

where h _in ^max is the length of the filter perforation interval of the observation well, selected from the maximum condition from a number of observation wells or the thickness of the reservoir, an uncased production casing in the observation well, selected from the maximum condition from a series of observation wells, m;
m is the coefficient of open porosity, d.ed .;
V _PL - the true flow rate of the underground fluid, m / min;
γ _W - the density of the reservoir fluid, kg / m ³ ;
d _well ^min - the internal diameter of the observation well, selected from the minimum condition from a number of observation wells, m;
g is the acceleration of gravity, m / s ² ;
Re is the Reynolds number for underground fluids;
γ _mg — density of indicator microgranules of each color, kg / m ³ ;
d _mg is the diameter of the indicator microgranules of each color, m;
d _then - the minimum size of the pore channels of the reservoir rocks, m;
h _St - the thickness of the layer of bound fluid, m,
mixed with the selected volume of reservoir fluid in a volume ratio of 0.0005: 0.001 - 1, respectively, and from the set of injection wells, central injection wells are located located in one or more horizons based on the area of the observation wells in terms of area, and each of them is injected the obtained suspension of the indicator of the same color in the reservoir fluid, determine the time interval through which the first sample is taken from the level of the wellbore fluid from each observation well located x in one or more horizons, according to the formula
t _lj-k = in l _j-k / V _pl + t _{float j} ,
where t _lj-k - the time interval through which the first sample is taken from the level of the wellbore fluid from the j-th observation well, min;
in - coefficient taking into account macrodispersion in the "frontal" part of the indicator concentration wave and errors in determining the true flow rate of the underground liquid, d.ed;
l _j-k - the distance from the middle of the perforation interval of the k-th central injection well to the middle of the interval of perforation of the filter or the middle of the reservoir layer without a casing in the j-th observation well, m;
t _pop.j is the time required for the indicator microgranules to _emerge from the lower holes of the filter perforation interval or the bottom of the reservoir, not cased by the production string, to the fluid level in the j-th observation well, min, equal

where h _j is the height of the reservoir fluid in the j-th observation well from the lower holes of the perforation interval of the filter or the bottom of the reservoir, not cased by production casing, j-th observation well, m,
and for each observation well, the sampling frequency of the reservoir fluid is determined by the expression
Δt _jk = (4V _z.k / mh _z.k π) ^0.5 (6V _pl ) ^-1 + t _pop.j ,
where Δ t _j-k - the time interval through which each subsequent sample is taken after the first from the level of the wellbore fluid from the j-th observation well, min;
V _c.c. - the injection volume of the indicator of the k-th color in the k-th central injection well, m ³ ;
h _c.c. - the length of the perforation interval in the k-th central injection well, through which the indicator of the k-th color, m, is introduced into the formation,
and the sampling end time for each observation well is found by the formula

where t _Σj-k is the end time of sampling for the j-th observation well, min;
in '- coefficient taking into account macrodispersion in the "tail" part of the wave concentration of the indicator and errors in determining the true flow rate of underground liquids, unit
moreover, in each sample taken, the indicator concentration of each color is determined, the corresponding indicator concentration of a similar indicator, previously received in the bottomhole formation zone, is found by the formula

where C _ij (t _ij-k ) is the concentration in the bottom-hole zone of the indicator of the k-th color in the i-th sample, taken from the level of the wellbore fluid from the j-th observation well, micro granules / m ³ , and t _ij-k is determined from the expression
t _ij-k = t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-to -t _pop.j ,
where t _ij-k is the time of arrival of the indicator of the k-th color in the bottomhole zone corresponding to the time of sampling of the i-th sample from the level of the borehole fluid of the j-th observation well, min;
t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-k — time of sampling of the i-th sample from the level of the borehole fluid in the j-th observation well, min;
h _mouth - the height of the device for sampling borehole fluid from the level of the j-th observation well, m;
C $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _jk (t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-k ) is the concentration of the indicator of the k-th color in the i-th sample taken from the level of the wellbore fluid from the j-th observation well, microgranules / m ³ ;
C $\genfrac{}{}{0ex}{}{\text{*}}{\text{1}}$ _jk (t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _1j-k ) is the concentration of the indicator of the k-th color in the i-1-st previous sample taken from the level of the wellbore fluid from the j-th observation well, microgranules / m ³ ;
d _mouth - the inner diameter of the device for sampling well fluid from the level of the j-th observation well, m;
V $\genfrac{}{}{0ex}{}{\text{*}}{\text{P}}$ _{l j-to} - the true flow rate of the reservoir fluid in the direction from the k-th injection well to the j-th observation well, m / min, determined from the expression
V $\genfrac{}{}{0ex}{}{\text{*}}{\text{P}}$ _{l j-k} = l _j-k m ^-1 (t $\genfrac{}{}{0ex}{}{\text{*}}{\text{l}}$ _ij-to -t _pop.j ) ^-1 ,
where t $\genfrac{}{}{0ex}{}{\text{*}}{\text{l}}$ _ij-k - time of the first sampling from the level of the borehole fluid in the j-th observation well, in which C $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _jk (t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _j-k ) ≠ 0, min;
h _in.j is the length of the filter perforation interval or the thickness of the reservoir, not cased by the production casing of the j-th observation well, m;
t $\genfrac{}{}{0ex}{}{\text{*}}{\text{i}}$ _-lj-k - sampling time of the i-1st previous sample taken from the level of the wellbore fluid in the j-th observation well, min,
and then, by the found set of values of the change in the concentration of the indicator of each color over time in the bottom-hole zone of the formation, its capacitive-filtration properties and the directions of liquid-phase flows are determined.  2. The method according to claim 1, characterized in that an organic luminescent substance based on dixanthylene is used in a blue indicator, fluorescein is used in a green indicator, rhodamine F is in a yellow indicator, rhodamine 200 V is in a red indicator, and melamine formaldehyde or melamine urea formaldehyde resin is used as the polycondensation resin.

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