CN1344911A - Generalized tracing and diluting method for monoporate penetration flow rate measurement - Google Patents

Abstract

The present invention is one generalized tracing and diluting method for monoporate penetration flow rate measurement. The method includes: measuring perpendicular flow inside the pore via peak-peak method; injecting tracer agent to the measured section of the pore in spot or sectional feeding mode; data acquisition to record density and variation of tracer agent; and calculating the osmotic flow rate and horizontal flow rate of underground water by applying generalized diluting method. Compared with prior art, the present invention is superior in that by means of the simple method, precise hydrogeological parameters may be obtained without stopping water flow.

Description

Measure the seepage velocity generalized tracing and diluting method in the single hole

One, affiliated technical field

The present invention relates to the measuring method of seepage velocity in the hydrogeological parameter, measure the seepage velocity generalized tracing and diluting method in particularly a kind of single hole.

Two, background technology

With the measuring seepage velocity that draws water is traditional method.The experiment of drawing water is by field measurement data such as aquifer yield, drawdown, times of pumping, adopts relevant well stream theory to inquire into hydrogeological parameters such as the infiltration coefficient in water-bearing zone, coefficient of transmissibility.But, the bailing test disturbance natural flow field, make its infiltration coefficient that determines can not reflect real underground water flow field, and, the theoretical problem that exists precision and usable range of the applied well stream of bailing test itself.In addition, also there is troublesome poeration in force in the experiment of drawing water, often will spend the problem of great amount of manpower and material resources.

More advanced seepage velocity means of testing is all being sought to alleviate the burden that bailing test is brought to people by the many countries of contemporary world, and tracing method is exactly wherein a kind of.Country's " THE HYDROGEOLOGICAL RECONNAISSANCE OF WATER-SUPPLY standard " that China revised in 2000 is the widely-used legal basis that provides of this technology with the regularization of isotopic dilution velocimetry.Its principle is to utilize the groundwater flow in the boring in tracer agent mark natural flow field or the artificial flow field, it is moved in the water-bearing zone, thereby measure some hydrogeological parameter of water-bearing zone with spike or dilution principle.Since people such as Moser had proposed to measure the some dilution process of groundwater seepage flow velocity in the individual well, single hole point dilution method had obtained very big development.The measuring principle of single hole dilution method be with the spike probe placement at measuring section, inject tracer agent, evenly stir, but the dilution rate of METHOD FOR CONTINUOUS DETERMINATION tracer agent like this, thereby measure phreatic seepage velocity, the computing formula of its seepage velocity is: $V_f=\frac{\mathrm{\πr}}{2\mathrm{\α}\·t}\ln \frac{N_0}{N},$ V wherein _fBe groundwater seepage flow velocity (m/d); R is pore radius (m); N ₀Tracer concentration when beginning to measure; Tracer concentration when N is time t; α is the flow distortion correction coefficient; T is a Measuring Time.The applicable elements of this method is: 1, can not there be vertical current in measuring section in the hole; The concentration of 2, dilution section each point keeps equating; 3, tracer concentration must be very low, otherwise the influence that will produce density difference.People's solutions to the problems described above such as W.Drost of Germany are: 1, the dilution chamber at the spike probe designs two inflation sealing embolisms up and down, and has designed an equalizing pipe, avoids the influence of vertical flow; 2, in the dilution cavity, stirrer is installed, is kept the concentration of each point in the dilution cavity to equate all the time; 3, select for use radioactive isotope as tracer agent, reduce the influence that density difference produces.Though this tracing method has solved the problems referred to above in theory, also developed corresponding probe and be applied to actual measurement, still, this probe manufacturing is very complicated, use is also extremely inconvenient, adopts radioactive isotope can not promote on a large scale as tracer agent.The most important is in the boring that strainer tube is installed, this method can not really stop vertical flow, because vertical flow may flow by the gravel of filling out between strainer tube and boring, even used equalizing pipe, the interference of avoiding vertical flow fully also is very difficult, particularly, when measured water-bearing zone was the water burst water-bearing zone, equalizing pipe had just lost effect.

Three, summary of the invention

1, goal of the invention:

The present invention to draw water experiment and the existing the problems referred to above of single hole point dilution process and has proposed in the single hole mensuration seepage velocity generalized tracing and diluting method in order to solve, its purpose is: 1, set up the spike method of testing of measuring hydrogeological parameter under a kind of more than water condition, the design of simplified measurement instrument and corresponding operating are as can be without the sealing embolism at tagging probe; 2, break the restriction that tracer agent can only use radioisotope tracer, increase available selection range of tracer, make the spike measuring technology be convenient to promote; 3, reduce of the influence of tracer concentration size to test result, must remain on the condition that the measuring section each point equates as tracer concentration in the former single hole point dilution method, the caused molecular diffusion of high concentration can be influential to test result simultaneously, and it is just right that these are difficult to accomplish in practical operation.

2, technical scheme: for achieving the above object, measuring the seepage velocity generalized tracing and diluting method in the single hole of the present invention is when carrying out the spike measurement, if adopt radioactive isotope as tracer agent, then use tagging probe, handle by the automatic record data of the computer-controlled data acquisition system (DAS) line correlation of going forward side by side; If adopt other material as tracer agent, then use corresponding surveying instrument image data, as salt during as tracer agent by high-precision conductivity meter record data.The concrete operations step is:

The first step: adopt the vertical flow in the peak-to-peak method mensuration hole.Understood in the underground water after the distribution situation of vertical flow, just can determine the source of throwing in wherein and carry out METHOD FOR CONTINUOUS DETERMINATION and calculating.If there is not vertical flow just can adopt the method for full hole or segmentation markers, if there is vertical flow, then tracer agent is thrown in vertical flow produces section zone, hole in the more uniform stratum several meters of general suitable selections, adopt point to throw when flow velocity is very big, be convenient to vertical flow and measure.Flow velocity hour can suitably increase the distance in throwing source, is used for measuring vertical flow but must leave enough hole sections.Obtain mistiming and distance between every adjacent two peak values after each peak value finds, can be similar to two peak-to-peak water-bearing zones as one deck, thickness is two peak-to-peak distances.

Second step, tracer agent is injected in the measured hole measured section, can adopt a throwing mode or segmentation to throw in the tracer agent mode.

In the 3rd step, carry out data acquisition, record tracer concentration size and variation.If previous step adopts some throwing mode, then can adopt fixed point to measure tracer concentration, or the mode METHOD FOR CONTINUOUS DETERMINATION tracer concentration of mobile probe is with the variation of the degree of depth; If previous step adopts segmentation to throw in mode, then can adopt of the variation of the mode METHOD FOR CONTINUOUS DETERMINATION tracer concentration of mobile probe with the degree of depth.

In the 4th step, use following broad sense dilution process and calculate the groundwater seepage flow velocity.

In the first step, can adopt the vertical flow velocity in the peak-to-peak method mensuration hole, according to the vertical flow velocity of being measured preliminary division is carried out in the disclosed water-bearing zone of holing.

Broad sense dilution process:, might as well establish its vertical flow direction and serve as reasons down upwards, referring to accompanying drawing 1 for arbitrary water-bearing zone that has vertical flow.Tracer agent is thrown between 2 of A, B, and continuous probe comprises that the tracer concentration of 2 of A, B changes.Current with respect to the downstream flow velocity in hole are: ${\mathrm{\ν}}_D=\frac{\mathrm{\πr}}{2\{t-\frac{({\mathrm{\ν}}_A-{\mathrm{\ν}}_B)t^2}{2h}+\frac{t^3}{6}{\[\frac{({\mathrm{\ν}}_A-{\mathrm{\ν}}_B)}{h}\]}^2-\frac{t^4}{24}{\[\frac{({\mathrm{\ν}}_A-{\mathrm{\ν}}_B)}{h}\]}^3+\·\·\·\·\·\·\}}\ln \frac{N_0}{N}---\left(1\right)$ In the formula: V _DBe groundwater seepage flow velocity (m/d); R is pore radius (m); N ₀Tracer concentration when beginning to measure; Tracer concentration when N is time t; T is a Measuring Time; V _AAnd V _BBe respectively the vertical flow velocity (m/d) of 2 of A, B

Then phreatic horizontal flow velocity can calculate with following formula: $V_f=\frac{\mathrm{\πr}}{2\mathrm{\α}\{t-\frac{({\mathrm{\ν}}_A-{\mathrm{\ν}}_B)t^2}{2h}+\frac{t^3}{6}{\[\frac{({\mathrm{\ν}}_A-{\mathrm{\ν}}_B)}{h}\]}^2-\frac{t^4}{24}{\[\frac{({\mathrm{\ν}}_A-{\mathrm{\ν}}_B)}{h}\]}^3+\·\·\·\·\·\·\}}\ln \frac{N_0}{N}---\left(2\right)$ In the formula: α be the flow distortion correction coefficient (method of determining is referring to document: the discussion of isotope single hole dilution method side reaction coefficient in the research of crack rock seepage flow, the prospecting science and technology, 2000 the 6th phases, pp3-7).

As can be seen from the above equation, in the hole, there is not vertical flow or work as V _A=V _BThe time, just become the formula that a dilution process is measured seepage velocity: $V_f=\frac{\mathrm{\πr}}{2\mathrm{\α}\·t}\ln \frac{N_0}{N}---\left(3\right)$

The vertical flow velocity V that measures _AAnd V _BRelative size relation different, corresponding current are with respect to the upstream flow rate V in hole _UWith downstream flow velocity V _DBe different, can divide 3 kinds of situations to analyze: 1) V _U=V _D, the hydrostatic head in water-bearing zone is identical with hole mixing water level, calculate flow velocity be exactly real seepage velocity.This moment V _A=V _B, in this case, the water-bearing zone between A, the B may be that permeable layer also may be an aquiclude, if N _A=N _B(N _AAnd N _BBe respectively A and B order the tracer agent counting rate that detected and), belong to aquiclude; If N _A＞N _B, belong to pervious bed; N _A＜N _BSituation be non-existent.Work as N _A＞N _BThe time satisfied the desired condition of broad sense dilution process in theory, but should satisfy N at least _A〉=5 N _BCould obtain result accurately.2) V _U＞V ₀, the vertical flow velocity V that measure this moment _B＞V _A, because some from the flow supply in water-bearing zone in the hole, cause vertical flow to increase.Upstream flow rate with respect to the hole is: $V_U=V_D+\frac{\mathrm{\πr}}{2h}\[(V_B-V_A)\]---\left(4\right)$

Have two kinds of different flow patterns in this case: the current part of (1) upstream, water-bearing zone has flowed into the water-bearing zone in downstream, become vertical flow in another part ostium, Kong Shui in the downstream supply to the water-bearing zone less, (Fig. 3 is a this flow pattern synoptic diagram in the horizontal direction) as shown in Figure 2, the dilution formula (4) that only can use broad sense under this condition calculates seepage velocity; (2) all supplies in the hole of the water of the upstream and downstream in water-bearing zone, there is not the dilution of horizontal direction in (Fig. 5 is a this flow pattern synoptic diagram in the horizontal direction) in the hole as shown in Figure 4, and just can not determine seepage velocity this moment.These two kinds of flow patterns can and be differentiated by 2 counting rates that detect of A, B: the former is N _A＞N _BLatter N _A=N _B3) V _U＜V _D, opposite with last a kind of situation, vertical flow velocity V _A＞V _B, the water-bearing zone is suction, Kong Shui has entered the water-bearing zone, causes the minimizing of vertical flow.

Also there are two kinds of flow patterns in this case: (1) and V _U＞V _DThe time first kind of flow pattern similar, difference only is that this moment Kong Shui is bigger to the increment in water-bearing zone, can adopt this moment broad sense dilution formula (2) to calculate, (4) formula of employing is revised result of calculation; (2) upstream in suction water-bearing zone also is suction, and (Fig. 7 is a this flow pattern synoptic diagram in the horizontal direction) as shown in Figure 6 can adopt broad sense dilution formula (1) to calculate flow velocity this moment.It is very simple distinguishing these two kinds of patterns: the flow that hole water flows into water-bearing zone between A, B is Q '=π r ²(v _A-v _B), and the flow velocity that utilizes (1) formula to obtain calculates the flow Q=π rhv that flows into this water-bearing zone _DIf, Q '=Q, then the whole horizontal flow in this water-bearing zone of explanation inflow all comes from Kong Shui, belongs to second kind of pattern; If Q '＜＜Q, belong to first kind of pattern, the flow velocity that is calculated this moment can be represented the actual seepage velocity of this layer basically; If Q ' is slightly less than Q, represent that the existing horizontal flow in this water-bearing zone has vertical flow again, this water-bearing zone hydrostatic head is little with the difference of mixing water level in the hole, also belongs to first kind of pattern, but this flow velocity has only reflected the phreatic seepage velocity of part.

3, beneficial effect: the present invention compared with prior art, its remarkable advantage is to adopt broad sense single hole point dilution method obtaining the higher hydrogeological parameter of precision under the water condition incessantly, and this method operates easier.The generalized tracing and diluting method of measuring seepage velocity in the single hole has relaxed three applicable elements of single hole point dilution method, detection method has been done following improvement: 1, tracer agent is not limited to isotope, also can adopt other material as tracer agent, as compounds such as salt; 2, adopt the method for integral measurement, utilize the spike surveying instrument under the situation of sealing not, the tracer concentration in the METHOD FOR CONTINUOUS DETERMINATION hole is obtained gross-count rate, calculates seepage velocity thereby use broad sense dilution formula; 3, adopt some input mode, can be applicable to the evenly section of distribution of water-bearing zone; 4, adopt vertical flow in the tracing method METHOD FOR CONTINUOUS DETERMINATION water-bearing zone such as peak-peak method, this is all applicable at the measuring section that vertical flow is distributed as straight line; 5, only require that tracer concentration each point on the boring section equates, do not require that the concentration between each section equates, this is satisfiable at internal diameter in less than the hole of 100mm basically, and this has also enlarged the range of application of tracer technique.

4, drawing explanation

Fig. 1 is the motion synoptic diagram of water in the hole when having vertical flow.The height of Kong Zhu is h between tested segment A, the B, and the radius in hole is r, and vertical flow is respectively V in the speed of 2 of A, B _AAnd V _BAB section water column supply source respectively from the horizontal flow q of upstream, water-bearing zone one side _UWith from A point vertical flow q from bottom to top _AThe same path that flows out water column also has two, flows out the q that B is ordered _BWith the q that flows to downstream, water-bearing zone one side _DArrow is represented water (flow) direction.

Fig. 2 represents V _B＞V _AThe time groundwater flow first kind of flow pattern, promptly the current part of upstream, water-bearing zone has flowed into the water-bearing zone in downstream, becomes vertical flow in another part ostium, Kong Shui in the downstream supply to the water-bearing zone less;

Fig. 3 is a this flow pattern synoptic diagram in the horizontal direction.

Fig. 4 represents V _B＞V _AThe time groundwater flow second kind of flow pattern, i.e. all supplies in the hole of the water of the upstream and downstream in water-bearing zone;

Fig. 5 is a this flow pattern synoptic diagram in the horizontal direction.

Fig. 6 represents V _A＞V _BThe time groundwater flow second kind of flow pattern, promptly Kong Shui flows to the water-bearing zone in the upstream and downstream both sides, the water level in water-bearing zone is lower than the hole water level; Fig. 7 is a this flow pattern synoptic diagram in the horizontal direction.

Fig. 8 develops the spike sonde configuration synoptic diagram of surveying vertical flow for W.Drost.Throwing source device is installed in probe middle part, and 4 radioactivity seekers such as G-M counter or NaI crystal scintillation counter are installed in the probe, and two are positioned at device top, throwing source, and two are positioned at the below in addition.

Fig. 9 is the mobile in time variation diagram of peak value of tracer concentration in the Bei Jiang of the Guangdong Province Shijiao Section experimental port.The right side is corresponding stratigraphic distribution among the figure.

The seepage velocity that Figure 10 measures when do not exist vertical flow in the hole low water season for this experimental port is with the hole depth change curve.The left side is a corresponding stratigraphic distribution in the hole among the figure.

Five, embodiment

With the Bei Jiang of Guangdong Province tracer experiment that Shijiao Section is carried out is example.

At first whether there is vertical flow in the hole, validating experiment hole.Probe and the method using the W.Drost development and propose, spike sonde configuration and method of testing are referring to Fig. 8.(the peak-to-peak method is measured vertical flow: if there is from bottom to top vertical flow behind the throwing source in the hole, two detectors on top will successively receive the GAMA ray that tracer agent sends, this intensity is directly proportional with tracer concentration, the peak value of concentration changes with time has been represented the tracer concentration center, and the distance between two detectors just can calculate vertical flow velocity divided by the mistiming of two peak values.If vertical flow moves downward, in like manner two of the bottom detectors will detect vertical flow velocity.Detector about when not having vertical flow to influence does not all receive tracer agent).

When application generalized tracing point dilution process carries out the spike test, adopt segmentation to throw in tracer agent mobile probe circulation measuring method, being about to tracer agent throws on the path of vertical flow, adopt of the variation of the mode METHOD FOR CONTINUOUS DETERMINATION tracer concentration of mobile probe with the degree of depth, up to the tracer agent cloud fully till this water-bearing interval disappears, obtain the concentration profile of many different times, the peak value of tracer concentration moves variation as shown in Figure 9 in the hole.The seepage velocity curve that Figure 10 measures when not having vertical flow for this hole.

Stratum that test hole discloses is divided into 5 " water-bearing zones ", and the meaning of peak point is the interphase in two " water-bearing zones ", the vertical flow velocity that thickness and the time to peak difference by " water-bearing zone " can calculate each peak point; Calculate the vertical current difference between two peak values then, actually obtain 6 groups of speed differences.Also to calculate each gross-count rate, and the deduction background.Its result of calculation has been displayed in Table 1 " water-bearing zone 2 " and has satisfied v referring to table 1 _i=v _I-1Condition; " water-bearing zone 1 " satisfies v _i＜v _I-1Condition; " water-bearing zone 3,4,5 " satisfies v _i＞v _I-1Condition.Adopt broad sense dilution formula (2) formula and some dilution formula (3) to calculate respectively.Also listed the relative error of formula (2) in the table 1 with (3) result of calculation.

The result of calculation that compares (2), (3) two formulas, the result who is obtained by (2) formula is very near actual conditions, through not having under the situation of vertical flow duplicate measurements repeatedly, the perviousness of " 3,4,5 layers " is approaching substantially, and Fig. 6 is the seepage velocity distribution curve that this hole measures when do not exist vertical flow in the hole low water season.Obviously be subjected to the influence of vertical flow by dilution formula (a 3) result calculated, reached 2.5 times with the maximum relative error of formula (2) result of calculation.

As can be seen, listed in the table 1 (Q '-Q)/and the ratio of Q ' is very little, and the maximal value shared from vertical flow be 2.63% only, and horizontal flow definitely is dominant, and the result of calculation of (2) formula is believable.(3) formula is to be applied to the situation that vertical flow exists, although it is very little to participate in the vertical flow of dilution, it is very big to the influence of adopting (3) formula result of calculation.Broad sense dilution formula (2) has been considered the variation of dilution volume, and it is the variable of time, and is relevant with the difference of vertical flow velocity.If vertical flow can accurately be measured, can obtain good result.

" water-bearing zone "		??1	??2	??3	????4	??5
								The corresponding well depth (m) of concentration curve peak value	??21.5	??24.25	??26.45	??28.8	????31.2	??33.8	??37.9
The thickness in " water-bearing zone " (m)		??2.75	??2.2	??2.35	????2.4	??2.6	??4.1
								The time interval between two peak values (Min)	??0	??16.4	??14.4	??15.6	????15.0	??13.6	??12.3
" water-bearing zone " vertical flow (m/Min)	??0.17	??0.15	??0.15	??0.16	????0.19	??0.33
								The vertical current differences of two " layers " (m/Min)		??0.02	??0	??-0.01	????-0.03	??-0.14
Gross-count rate behind the deduction background	??8575	??8439	??8395	??6794	????5199	??2966	??1998
								Horizontal flow Q ' (L/Min)		??2.915	??0.868	??34.65	????46.54	??116.85
Vertical flow Q (L/Min)		??0.0769	??0	??-0.0387	????-0.115	??-0.539
								(Q’-Q)/Q’		??0.9737	??1	??1.00112	????1.0025	??1.0046
Vf adopts (10) formula to calculate (m/d)		??0.070	??0.014	??0.45	????0.46	??0.47
								Vf adopts (9) formula to calculate (m/d)		??0.039	??0.014	??0.54	????0.71	??1.63
(9) with the relative error of (10) formula		??44％	??0	??-20％	????-54％	??-250％

Claims (1)

1, a kind of single hole is measured the seepage velocity generalized tracing and diluting method, and its characteristics are that its assay method comprises the steps:

The first step: adopt the vertical flow in the peak-to-peak method mensuration hole;

Second step, tracer agent is injected in the measured hole measured section, adopt some throwing mode or segmentation to throw in the tracer agent mode;

In the 3rd step, carry out data acquisition, record tracer concentration size and variation;

In the 4th step, use following broad sense dilution process and calculate the groundwater seepage flow velocity:

Tracer agent is thrown between 2 of A, B, and continuous probe comprises that the tracer concentration of 2 of A, B changes, and calculates the downstream flow velocity by following numerical expression: ${\mathrm{\ν}}_D=\frac{\mathrm{\πr}}{2\{t-\frac{({\mathrm{\ν}}_A-{\mathrm{\ν}}_B)t^2}{2h}+\frac{t^3}{6}{\[\frac{({\mathrm{\ν}}_A-{\mathrm{\ν}}_B)}{h}\]}^2-\frac{t^4}{24}{\[\frac{{\mathrm{\ν}}_A-{\mathrm{\ν}}_B}{h}\]}^3+\·\·\·\·\·\·\}}\ln \frac{N_0}{N}---\left(1\right)$ In the formula: V _DBe groundwater seepage flow velocity (m/d); R is pore radius (m); N ₀Tracer concentration when beginning to measure; Tracer concentration when N is time t; T is a Measuring Time; v _aAnd v _bBe respectively the vertical flow velocity (m/d) of 2 of A, B

Calculate phreatic horizontal flow velocity by following numerical expression: $V_f=\frac{\mathrm{\πr}}{2\mathrm{\α}\{t-\frac{({\mathrm{\ν}}_A-{\mathrm{\ν}}_B)t^2}{2h}+\frac{t^3}{6}{\[\frac{({\mathrm{\ν}}_A-{\mathrm{\ν}}_B)}{h}\]}^2-\frac{t^4}{24}{\[\frac{({\mathrm{\ν}}_A-{\mathrm{\ν}}_B)}{h}\]}^3+\·\·\·\·\·\·\}}\ln \frac{N_0}{N}---\left(2\right)$ In the formula: α is the flow distortion correction coefficient.

Images