A kind of Fluid Identification Method being applicable to Sandstone Gas ReservoirTechnical field
The invention belongs to fluid identification of reservoir technical field, relate to a kind of Fluid Identification Method being applicable to Sandstone Gas Reservoir, the method can be used for oil well logging data interpretation.
Background technology
Fluid identification is the important problem that Sandstone Gas Reservoir well log interpretation faces.Sandstone Gas Reservoir degree of porosity is little, and irreducible water saturation is high, cause electric logging and porosity logging less for the response difference of oil reservoir, oil-water common-layer, water layer, even cannot distinguish, bring difficulty to fluid identification.
The people such as Shi Fengxiang (first dam CONTINENTAL FACIES IN Sandstone Gas Reservoir flow net model method, inland river science and technology, 2012, (7): 101-101,157) for the geology characteristic of first dam CONTINENTAL FACIES IN tight sand, utilize Using Conventional Logs, investigated three porosity differential technique and the properties of fluid in bearing stratum recognition methods such as ratio method, water saturation and degree of porosity intersection, apparant formation water resistivity normal distribution method (P ~ 1/2), depth al-lateral resistivity differential technique, achieve good effect when this block is applied.
Li Zhong equality people (must two sections of gas reservoir well log interpretation new methods inquire into by new field, petroleum gas journal, 2011, (11): 98-102) utilize FZI (fluxion strap index) to set up well logging fluid identification that log interpretation model and " five terminal unit six factors " method carry out reservoir.Research shows, can improve the Explanation Accuracy of porosity and permeability with the log interpretation model that FZI sets up; " five terminal unit six factors " comprehensive recognition mode of well logging fluid covers lithology, physical property, hydrocarbonaceous characteristic, fracture development probability and the removable ability of hydro carbons, effectively can improve the degree of accuracy of properties of fluid in bearing stratum identification.
The people such as Wang Zhilei (log correlation analysis and the application in Methed of Tight Sandstone Gas Layers identification thereof, Journal of Engineering Geophysics, 2011, (1) the Methed of Tight Sandstone Gas Layers Logging Identification Method based on neutron well logging and density log, resistivity logging and density log dependency relation: 68-71) is proposed, then corresponding computer program is worked out, achieve the index of correlation that full well section calculates log automatically, and then reach the object identifying Methed of Tight Sandstone Gas Layers.More than 80% is reached to 7 mouthfuls of identifying processing well log interpretation formation testing coincidence rates having the gas well of test to carry out of central area in Sichuan Xu jiahe.
The people such as Li Chaoliu (a kind of new method and application thereof evaluating Sandstone Gas Reservoir pore structure, AppliedGeophysics, 2010, (3): 283-291,294) propose the impact of pore structure on resistivity to be normalized correction and the evaluation method based on the complete moisture resistivity R0 of nuclear magnetic resonance log predicting reservoir, thus outstanding properties of fluid in bearing stratum changes the electrical change caused, and provide a kind of new Sandstone Gas Reservoir fluid identification thinking.
The people such as Li Shaoxia (utilize nuclear magnetic resonance information to evaluate Methed of Tight Sandstone Gas Layers, oil instrument, 2008, (3): 54-57) analyze nuclear magnetic resonance log, in tight sand formation evaluation, there is special rule, based on rock sample nuclear magnetic resonance experiment is analyzed, set forth NMR logging data and solved the problems and solutions such as tight sand lithology classification, fluid identification, geologic parameter calculating and pore Structure Analysis.
Can find out, in existing Sandstone Gas Reservoir well log interpretation, fluid identification depends on the special well logging such as nuclear magnetic resonance, electromagnetic wave logging more, or relies on log data, and uses conventional logging to carry out Sandstone Gas Reservoir fluid identification also not have reliable method at present.
Summary of the invention
Technical problem to be solved by this invention is for the deficiencies in the prior art, provides a kind of Fluid Identification Method being applicable to Sandstone Gas Reservoir.The method is by calculating the nonuniformity coefficient of the apparant formation water resistivity of reservoir, and set up the corresponding relation of the phase attribute of known reservoir and the nonuniformity coefficient of apparant formation water resistivity, thus the phase attribute of the nonuniformity coefficient of the apparant formation water resistivity of reservoir to reservoir to be explained is utilized to identify.
For this reason, the invention provides a kind of recognition methods for Sandstone Gas Reservoir fluid, comprising:
Steps A, calculates the nonuniformity coefficient of the apparant formation water resistivity of known reservoir;
Step B, determines the phase attribute of known reservoir according to the test data of known reservoir, and sets up the corresponding relation of the phase attribute of known reservoir and the nonuniformity coefficient of apparant formation water resistivity;
Step C, calculates the nonuniformity coefficient of the apparant formation water resistivity of reservoir to be explained, and according to the phase attribute of known reservoir set up in step B with the corresponding relation of the nonuniformity coefficient of apparant formation water resistivity to determine the phase attribute of reservoir to be explained.
According to the present invention, in steps A and C, the nonuniformity coefficient calculating the apparant formation water resistivity of reservoir comprises:
Step M, makes the integral distribution curve of the apparant formation water resistivity of reservoir;
Step N, calculates the nonuniformity coefficient of the apparant formation water resistivity of reservoir according to formula (I);
F=Rk1/ Rk2formula (I)
Wherein, k1be the first cumulative frequency percentage, its span is 60%-90%;
K2be the second cumulative frequencies percentage, k2=k1-50%;
Rk1apparant formation water resistivity corresponding to first cumulative frequency percentage;
Rk2apparant formation water resistivity corresponding to second cumulative frequency percentage;
F is the nonuniformity coefficient of the apparant formation water resistivity of reservoir.
In a preferred embodiment of the invention, k1be 60%, k2be 10%.
In an embodiment of the invention, the nonuniformity coefficient calculating the apparant formation water resistivity of reservoir also comprises step L, calculates the apparant formation water resistivity of each sampling depth point of reservoir according to formula (II);
Formula (II)
Wherein, Rwafor apparant formation water resistivity;
Rtfor deep investigation resistivity;
Ф is degree of porosity, is calculated by porosity logging curve;
A, m are Archie formula coefficient, are determined by regional rock-electric test.
In the present invention, the computational methods of degree of porosity Ф are according to " geophysical information integrated interpretation " (Sun Jianmeng, Wang Yonggang, publishing house of University of Petroleum, calendar year 2001,18-20 page).
In the present invention, the defining method of Archie formula coefficient a, m is according to defining method certificate " geophysical information integrated interpretation " (Sun Jianmeng, Wang Yonggang, publishing house of University of Petroleum, calendar year 2001,23 pages).
In one embodiment of the invention, described deep investigation resistivity comprises deep lateral resistivity or deep induction resistivity.
In another embodiment of the present invention, described porosity logging curve comprises density, neutron or acoustic logging.
Term described in the present invention " fluid properties " i.e. phase attribute, described phase attribute kit oil scraper layer, water layer or oil-water common-layer.
Term described in the present invention " known reservoir " refers to the reservoir of test data, and described test packet draws together the yield data (oil production, aquifer yield), test result etc. that oil well test obtains.
Term described in the present invention " reservoir to be explained " refers to be needed to determine its phase attribute with well-log information, that is determines that it is the reservoir of oil reservoir, water layer or oil-water common-layer.
In well log interpretation, reservoir apparant formation water resistivity is the parameter of reflection formation fluid property.For water layer, the fluid in reservoir comprises irreducible water and moveable water, and therefore water layer apparant formation water resistivity uniformity better (all close to formation water resistivity); And for oil reservoir, the fluid in reservoir comprises irreducible water and moveable oil, due to the non-homogeneity of Sandstone Gas Reservoir, different depth point RESERVOIR PORE STRUCTURE is variant, irreducible water saturation is different, and corresponding oil saturation is also different, and therefore oil reservoir apparant formation water resistivity uniformity is relatively poor.The present inventor, through large quantity research, for the difficult point of the phase Attribute Recognition of Sandstone Gas Reservoir, develops a kind of Fluid Identification Method being applicable to Sandstone Gas Reservoir.The method based on the integral distribution curve of the apparant formation water resistivity of reservoir, by calculating the apparant formation water resistivity R corresponding to the first cumulative frequency percentagek1with the apparant formation water resistivity R corresponding to the second cumulative frequency percentagek2ratio as the nonuniformity coefficient of the apparant formation water resistivity of reservoir, and set up the corresponding relation of the phase attribute of known reservoir and the nonuniformity coefficient of apparant formation water resistivity, thus the phase attribute of the nonuniformity coefficient of the apparant formation water resistivity of reservoir to reservoir to be explained is utilized to identify.
The phase attribute of the inventive method identification reservoir does not rely on resistivity absolute value, and adopts the nonuniformity coefficient of apparant formation water resistivity, better can identify fluid properties in Sandstone Gas Reservoir.
Sandstone Gas Reservoir is the important exploration targets in current oil and gas exploration.The present invention is directed to the fluid identification difficult point in Sandstone Gas Reservoir well log interpretation, new fluid identification coefficient is proposed, utilize the phase attribute of this coefficient to reservoir to identify, effectively can be applied to Sandstone Gas Reservoir well log interpretation research and production work, have wide practical use.
Accompanying drawing explanation
Below in conjunction with accompanying drawing, the present invention is described.
Fig. 1 is the flow chart in embodiment 1, certain tight sand oil field being carried out to fluid identification.
Fig. 2 is the apparant formation water resistivity cumulative distribution table of two layers to be explained.
Detailed description of the invention
For making the present invention easier to understand, describe the present invention in detail below in conjunction with embodiment and accompanying drawing, these embodiments only play illustrative effect, are not limited to range of application of the present invention, NM specific experiment method in the following example, conveniently experimental technique carries out usually.
Embodiment
Embodiment 1:
The inventive method is utilized to carry out the flow process of fluid identification as shown in Figure 1 in tight sand oil field, somewhere.
1. make the integral distribution curve of the apparant formation water resistivity of known reservoir, and calculate the nonuniformity coefficient of known reservoir apparant formation water resistivity.
(1) apparant formation water resistivity R is calculated to the known reservoir (having the reservoir of test data) of 16 mouthfuls of well C8 layer positions, this oil fieldwa, do the integral distribution curve of the apparant formation water resistivity of this known reservoir.
(2) the nonuniformity coefficient f of the apparant formation water resistivity of reservoir is calculated according to formula (I):
F=Rk1/ Rk2formula (I)
Wherein, k1be the first cumulative frequency percentage, its span is 60%;
K2be the second cumulative frequencies percentage, k2=10%;
Rk1apparant formation water resistivity corresponding to first cumulative frequency percentage;
Rk2apparant formation water resistivity corresponding to second cumulative frequency percentage;
F is the nonuniformity coefficient of the apparant formation water resistivity of reservoir.
2. determine the phase attribute of known reservoir according to the test data of known reservoir, and set up the corresponding relation of the phase attribute of known reservoir and the nonuniformity coefficient of apparant formation water resistivity, in table 1.
The corresponding relation of the phase attribute of the known reservoir of table 1 and the nonuniformity coefficient of apparant formation water resistivity
3. make the integral distribution curve of the apparant formation water resistivity of reservoir to be explained, and calculate the nonuniformity coefficient of reservoir CX5 well 2135-2149 rice (No. 1 floor) to be explained and CX9 well 2266-2279 rice (No. 2 floor) apparant formation water resistivity.
(1) calculate the apparant formation water resistivity of two reservoirs to be explained respectively, and make apparant formation water resistivity integral distribution curve (as shown in Figure 2).
(2) as shown in Figure 2, corresponding during accumulated value 60% on No. 1 floor apparant formation water resistivity cumulative distribution table apparant formation water resistivity R60=0.160 ohm meter, apparant formation water resistivity R corresponding during aggregate-value 10%10=0.055 ohm meter, calculates the nonuniformity coefficient f=2.91 obtaining its apparant formation water resistivity thus.
(3) as shown in Figure 2, corresponding during accumulated value 60% on No. 2 floor apparant formation water resistivity cumulative distribution tables apparant formation water resistivity R60=0.335 ohm meter, apparant formation water resistivity R corresponding during aggregate-value 10%10=0.185 ohm meter, nonuniformity coefficient f=1.81.
4. utilize the corresponding relation of the phase attribute of the known reservoir in table 1 and the nonuniformity coefficient of apparant formation water resistivity to carry out fluid identification to CX5 well 2135-2149 rice (No. 1 floor) and CX9 well 2266-2279 rice (No. 2 floor).
(1) the nonuniformity coefficient f=2.91 of reservoir CX5 well 2135-2149 rice (No. 1 floor) apparant formation water resistivity to be explained, according to the corresponding relation of the phase attribute of the known reservoir in table 1 and the nonuniformity coefficient of apparant formation water resistivity, No. 1 floor is judged as oil reservoir.
(2) the nonuniformity coefficient f=1.81 of reservoir CX9 well 2266-2279 rice (No. 2 floor) apparant formation water resistivity to be explained, according to the corresponding relation of the phase attribute of the known reservoir in table 1 and the nonuniformity coefficient of apparant formation water resistivity, No. 2 floor are judged as water layer.
No. 1 floor test day produce oil 16.28 side, produce water 0.77 side, test result is oil reservoir; No. 2 floor test day produce oil 0.15 sides, daily output water 1.58 side, test result is water layer.The result utilizing the present invention to carry out fluid identification to two layers is equal consistent with test result.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.