CN104933281A - Optimization for selecting oil and gas exploration zones - Google Patents

Abstract

The invention discloses a method for optimizing oil and gas exploration zones. The method comprises the following steps: a hydrocarbon source evolution and recovery step of recovering a hydrocarbon source rock kerogen hydrocarbon generation history, utilizing a reservoir temperature history and a pyrolysis temperature window method to determine the generation time of fossil oil reservoir pyrolysis gas and adopting a paleotectonic map and a Goodwin figure method to obtain a spatiotemporal evolution process of a fossil oil reservoir pyrolysis hydrocarbon kitchen; a caprock seal ability evolution and recovery step of in a building stage, utilizing a porosity-displacement pressure history method to recover a forming process of muddy caprock seal ability in the building stage, and in a transformation stage, utilizing a permeability-displacement pressure history method to recover a displacement pressure evolution history of a muddy caprock in a lifting process and adopting an over-consolidation ration (OCR) history method to quantitatively restrict a seal ability evolution process of the muddy caprock in the lifting process; and a source caprock matching judgment step of judging the precedence relationship among the forming time of the muddy caprock seal ability, the hydrocarbon generation time of the underlying hydrocarbon source rock kerogen of the muddy caprock and the generation time of the fossil oil reservoir pyrolysis gas, and determining whether the caprock is a dynamic effective caprock in geological time.

Description

A kind of method of preferred oil gas exploration zone

Technical field

The present invention relates to oil-gas exploration technical field, specifically, relate to a kind of method of preferred oil gas exploration zone.

Background technology

Through the accumulation of nearly more than 50 years, at present, China have accumulated rich experience in oil-gas exploration, and achieves a lot of breakthrough to the concrete research aspect of " life, storage, lid, circle, fortune, guarantor " six key elements of Hydrocarbon Formation Reservoirs, becomes the basic theory instructing oil-gas exploration.In recent years, the enforcement of National 973 project (2005CB422108), achieves the new knowledge from " source control opinion " to " source-lid control hydrocarbon ".Recognize that marine carbonate sequence Sheng Ting center might not be deposition or subsiding center, oil gas has multi-source many phases raw hydrocarbon, the feature of freight index future of many phases and adjustment and reconstruction of many phases, and, Marine Hydrocarbon Source Rocks, especially often evolution level is high for Lower Palaeozoic marine hydrocarbon source rocks, generally reach the post-mature dry gas evolutionary phase, rock gas becomes the Main Resources of China's marine strata exploration, but natural gas molecule is little, easily scatter and disappear, require harsher to cap rock and preservation condition, the marine oil and gas regularity of distribution comparatively continental basins is more complicated.

How evaluating hydrocarbon source and cap rock from the angle of dynamic evolution, becoming marine carbonate sequence oil-gas exploration selection and appraisal of exploration area needs the urgent problem solved.

Summary of the invention

The present invention is directed to the above-mentioned problems in the prior art, provide a kind of method of preferred oil gas exploration zone, comprising:

Hydrocarbon source evolution recovering step, recovers the raw hydrocarbon history of hydrocarbon protolith kerogen, utilizes the time of reservoir temperature history and cracking temperature window method determination Foregone pool cracking anger, and adopts paleostructural map and palaeogeothermal figure method to obtain the temporal-spatial evolution process of Foregone pool cracking hydrocarbon kitchen;

Enclosing capability evolution recovering step, in the construction phase, utilizes factor of porosity-replacement pressure history method to recover the forming process of construction phase shale Enclosing capability; At alteration stage, utilize permeability-replacement pressure history method to recover the replacement pressure Evolutionary History of shale cap rock in lifting process, adopt over-consolidation ratio OCR history standard measure to constrain in the closure evolutionary process of shale cap rock in lifting process;

Source lid matching judgment step, covers the precedence relationship of the time of hydrocarbon protolith kerogen hydrocarbon generation time and Foregone pool cracking anger under judging the time that shale Enclosing capability is formed and described shale cap rock, determine whether cap rock is dynamic effectively cap rock in the geologic epoch.

According to one embodiment of present invention, in described hydrocarbon source evolution recovering step, the time of reservoir temperature history and cracking temperature window method determination Foregone pool cracking anger is utilized to comprise:

Utilize buried history and Thermal history to calculate Foregone pool reservoir in the palaeotemperature in earth history period, palaeotemperature is contrasted with the crude oil pyrolysis temperature window of being determined by sample experiments data, determines the time of the crude oil pyrolysis anger in Foregone pool.

According to one embodiment of present invention, in described hydrocarbon source evolution recovering step, the temporal-spatial evolution process utilizing paleostructural map and palaeogeothermal figure to obtain Foregone pool cracking hydrocarbon kitchen comprises:

Utilize the locus of paleostructural map determination geology period of history Foregone pool cracking hydrocarbon kitchen, establishment palaeogeothermal figure determination Foregone pool is in the palaeotemperature in earth history period, the time of described Foregone pool cracking anger is obtained in conjunction with described crude oil pyrolysis temperature window, and the dynamic migration process of described Foregone pool cracking hydrocarbon kitchen.

According to one embodiment of present invention, in described Enclosing capability evolution recovering step, in the construction phase, the forming process utilizing factor of porosity-replacement pressure history method to recover construction phase shale Enclosing capability comprises:

In the construction phase, calculate the old Jun procelain history of shale cap rock according to the ancient buried depth of geology period of history, described old Jun procelain history is: $\mathrm{\φ}(Z,t)=P_1{\mathrm{\φ}}_1{e}^{-c_{1}Z}+P_2{\mathrm{\φ}}_2{e}^{-c_{2}Z}+P_3{\mathrm{\φ}}_3{e}^{-c_{3}Z}+...+P_n{\mathrm{\φ}}_n{e}^{-c_{n}Z},$

Wherein, φ (Z, t) is at Geologic Time t, factor of porosity when buried depth is Z, P ₁, P ₂, P ₃..., P _nfor formation lithology percentage composition; c ₁, c ₂, c ₃..., c _nfor corresponding lithology compaction coefficient; φ ₁, φ ₂, φ ₃..., φ _n, be corresponding lithology sediment initial porosity; Z is the buried depth of Geologic Time t;

The variation relation between construction phase shale cap rock replacement pressure history and factor of porosity history is determined: P based on sample measured data _c(Z, t)=f φ (Z, t)=f (φ ₀e ^-cZ),

Wherein, P _c(Z, t) is Geologic Time t, replacement pressure when buried depth is Z, φ ₀for earth's surface factor of porosity, obtain funtcional relationship f by sample actual measurement replacement pressure and porosity data the Fitting Calculation;

According to construction phase shale cap rock replacement pressure history P _c(Z, t) recovers the forming process of closure.

According to one embodiment of present invention, in described Enclosing capability evolution recovering step, at alteration stage, utilize permeability-replacement pressure history method to recover the replacement pressure Evolutionary History of shale cap rock in lifting process and comprise:

At alteration stage, set up the funtcional relationship △ K between the knots modification of shale cap rock permeability and the knots modification of confined pressure _p=-0.2K ₀× ln (△ P)-0.2K ₀, wherein, △ K _pfor the knots modification of permeability, △ P is the knots modification of confined pressure, K ₀for original permeability;

Experimentally data fitting obtains the funtcional relationship P between the replacement pressure history of alteration stage and permeability history _c(Z, t)=0.253 × K (Z, t)- ^0.747, wherein, P _c(Z, t) is Geologic Time t, replacement pressure when buried depth is Z, and K (Z, t) is Geologic Time t, permeability when buried depth is Z;

According to P _c(Z, t)=0.253 × K (Z, t)- ^0.747recover the replacement pressure Evolutionary History of shale cap rock in lifting process.

According to one embodiment of present invention, the OCR parameter in described over-consolidation ratio OCR history method is

$\mathrm{OCR}(Z,t)=\frac{{{\mathrm{\σ}}^{\′}}_{v\max }}{{{\mathrm{\σ}}^{\′}}_v}=\frac{({\mathrm{\ρ}}_1-{\mathrm{\ρ}}_w)\×Z_1}{({\mathrm{\ρ}}_2-{\mathrm{\ρ}}_w)\×Z_t},$

Wherein, σ ' _vmaxfor the maximum perpendicular effective pressure that mud stone experiences, σ ' _vfor buried depth is Z _tvertical effective pressure, ρ ₁for stratigraphic rock density during maximum buried depth, ρ ₂for buried depth is Z _tburied depth time rock density, ρ _wfor local water density, Z ₁for maximum buried depth, Z _tfor the ancient buried depth in lifting process.

According to one embodiment of present invention, in described Enclosing capability evolution recovering step, the closure evolutionary process utilizing over-consolidation ratio OCR parameter quantitative to constrain in shale cap rock in lifting process comprises:

When described over-consolidation ratio OCR parameter is greater than or equal to 2.5, shale cap rock breaks, and loses closure.

According to one embodiment of present invention, in the lid matching judgment step of described source, when covering the time of hydrocarbon protolith hydrocarbon generation time and Foregone pool cracking anger under the formation time of shale Enclosing capability is early than described cap rock, described cap rock is dynamic effectively cap rock, and source lid matching relationship is the relation being conducive to Hydrocarbon Formation Reservoirs and preservation.

Present invention offers following beneficial effect: solve the angry history of Foregone pool cracking and recover problem and cracking hydrocarbon kitchen dynamic characterization problem, and solve Enclosing capability dynamic evolution and recover problem, can from the angle rapid quantitatively evaluating oil gas effect preservation condition of dynamic evolution, preferred favourable exploration areas band, fast prediction favorable oil/gas distributive province, and for exploration target evaluation in Favorable Zones with preferably provide foundation, the in the urgent need to address technical bottleneck evaluated about " effective preservation condition " that the oil-gas exploration selection and appraisal of exploration area of the marine facies poly-cyclic basin under preliminary solution many phases tectonic reworking background faces.

Other features and advantages of the present invention will be set forth in the following description, and, partly become apparent from instructions, or understand by implementing the present invention.Object of the present invention and other advantages realize by structure specifically noted in instructions, claims and accompanying drawing and obtain.

Accompanying drawing explanation

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in further detail.

Fig. 1 is the method flow diagram of the preferred oil gas exploration zone of the embodiment of the present invention;

Fig. 2 is the crude oil pyrolysis temperature window of simulated experiment result reflection;

Fig. 3 is the process flow diagram of the sub-step that evolution recovering step in hydrocarbon source comprises;

Fig. 4 is the process flow diagram of the sub-step that Enclosing capability evolution recovering step comprises;

Fig. 5 is rock replacement pressure and the total porosity graph of a relation of lab analysis test;

Fig. 6 a is the variation relation figure of factor of porosity with confined pressure of supracrustal rocks in uplift erosion process;

Fig. 6 b is the variation relation figure of permeability with confined pressure of supracrustal rocks in uplift erosion process;

Fig. 7 is the graph of a relation that under logarithmic coordinate system, shale cap rock permeability changes with confined pressure;

Fig. 8 is the graph of a relation that under linear coordinate system, shale cap rock permeability changes with confined pressure;

Fig. 9 is the graph of a relation of construction phase shale cap rock factor of porosity and permeability;

Figure 10 is shale cap rock permeability and replacement pressure graph of a relation;

Figure 11 is area, Weiyuan prestige 28 well maturity of organic matter history sectional view;

Figure 12 is area, Weiyuan prestige 28 well Cambrian system, the raw hydrocarbon history figure of Permian hydrocarbon source rock;

Figure 13 is the angry history figure of area, Weiyuan prestige 28 well Sinian system Foregone pool cracking;

Figure 14 is prestige 28 down-hole Palaeozoic caprocks buried history;

Figure 15 is prestige 28 down-hole Palaeozoic caprocks factor of porosity history;

Figure 16 is prestige 28 down-hole Paleozoic erathom shale cap rock replacement pressure history;

Figure 17 a and Figure 17 b is prestige 28 well OCR Evolutionary History figure;

Figure 18 is area, Weiyuan prestige 28 Jing Yuan lid dynamic evolution matching relationship figure;

Figure 19 is Leshang-Longnusi Paleo-uplift reservoir water salinity and Metamorphic Coefficient schematic diagram.

Embodiment

Describe embodiments of the present invention in detail below with reference to drawings and Examples, to the present invention, how application technology means solve technical matters whereby, and the implementation procedure reaching technique effect can fully understand and implement according to this.It should be noted that, only otherwise form conflict, each embodiment in the present invention and each feature in each embodiment can be combined with each other, and the technical scheme formed is all within protection scope of the present invention.

For the oil-gas exploration selection and appraisal of exploration area of marine facies poly-cyclic basin that experienced by tectonic reworking of many phases, not only hydrocarbon source condition is important, and cap rock and preservation condition are also most important.The present invention aims to provide a kind of method of preferred oil gas exploration zone, utilize source-lid dynamic evolution assessment technique, with hydrocarbon source rock (comprising Foregone pool) and upper caldding layer thereof for object, to disclose the formation of hydrocarbon primary rock producing hydrocarbon (comprise Foregone pool crude oil pyrolysis angry) process and Enclosing capability and/or destructive process and space-time dynamic matching relationship therebetween for target, evaluate and preserve validity.The dynamic evolution mainly comprising " source " recovers, the dynamic evolution of " lid " recovers and the technology contents of source-lid Dynamic Matching Relationship Prediction three aspects.Its meaning is, for the evaluation of oil gas effective preservation condition, the prediction of favourable oil-gas exploration zone and target preferably provide foundation.

In source-lid dynamic evolution assessment technique, for the dynamic evolution in " source ", carry out the angry history of buried history, thermal history, hydrocarbon primary rock producing hydrocarbon history and Foregone pool cracking and recover; For the dynamic evolution of " lid ", carry out cap rock factor of porosity history, permeability history, cap rock replacement pressure history and over-consolidation ratio OCR (overconsolidationratio) history to recover, on the basis of the dynamic evolution in " source " with the dynamic evolution recovery of " lid ", then carry out source-lid Dynamic Matching relation research.

embodiment one

Fig. 1 is the method flow diagram of the preferred oil gas exploration zone of the embodiment of the present invention, comprising:

Step S101, hydrocarbon source evolution recovering step, recover except the raw hydrocarbon history of hydrocarbon protolith kerogen except adopting maturation method, also utilize the time of reservoir temperature history and cracking temperature window method determination Foregone pool cracking anger, and adopt paleostructural map and palaeogeothermal figure method to obtain the temporal-spatial evolution process of Foregone pool cracking hydrocarbon kitchen;

Step S102, Enclosing capability evolution recovering step, in the construction phase, utilizes factor of porosity-replacement pressure history method to recover the forming process of construction phase shale Enclosing capability; At alteration stage, utilize permeability-replacement pressure history method to recover the replacement pressure Evolutionary History of shale cap rock in lifting process, adopt over-consolidation ratio OCR history standard measure to constrain in the closure evolutionary process of shale cap rock in lifting process;

Step S103, source lid matching judgment step, covers the precedence relationship of the hydrocarbon generation time of hydrocarbon protolith and the time of Foregone pool cracking anger, determines the dynamic validity of closed cap under judging the time that shale Enclosing capability is formed and described shale cap rock;

When covering the time of hydrocarbon protolith hydrocarbon generation time and Foregone pool cracking anger under the formation time of shale Enclosing capability is early than described cap rock, described cap rock is dynamic effective cap rock, and source lid matching relationship is the relation being conducive to Hydrocarbon Formation Reservoirs and preservation.

Wherein, the sequencing of step S101 and step S102 is interchangeable.

Before the idiographic flow describing each step in detail, first provide the deterministic process of embodiment of the present invention Crude Oil cracking temperature window numerical range.

At high temperature can there is cracking and generate rock gas in crude oil, but when there is cracking, namely under geologic condition, when how high temperature is will there is cracking in crude oil, and how high the lower limit temperature that petroleum liquid is preserved be, about this problem, many scholars carried out experimental study, although concrete temperature data is because of the difference of experiment condition and specimen material, also there is certain difference in result data, still has property unanimous on the whole understanding generally.Below the general introduction of the achievement in research of some of them scholar:

Someone thinks that crude oil is only stable (Schenk et al. under 150 DEG C, 1997), crude oil is after temperature is more than 150 DEG C, just unstable feature (Hunt is obviously shown, 1979), high molecular hydro carbons and other heterocycle potpourris gradate as low molecule potpourri (white oil and gaseous hydrocarbon) and pyrolyzed bitumen.Also someone thinks that the equilibrium temperature of crude oil can reach 200 DEG C of (Horsfield et al., 1992; Schenk et al., 1997; Domin é et al., 2002), somebody thinks that crude oil starts the temperature of cracking may more early, about 80 DEG C ~ 100 DEG C (Kuo et al., 1994).On Geological Scale, 150 DEG C ~ 200 DEG C become Tibetan to have important control action (Guo Liguo etc., 2008) for crude oil pyrolysis with pyrolysis gas.

The composition of the cracking temperature of crude oil and crude oil itself, Material Source have certain relation, and dissimilar crude oil pyrolysis temperature is also different.High-wax oil cracking starts from 180 DEG C, and cracking peak temperature is 225 DEG C, and Marine Crude Oil cracking starts from 170 DEG C, and cracking peak temperature is 215 DEG C, and lower than under 160 DEG C of conditions, crude oil pyrolysis is difficult to (Schenk et al., 1997 occur; Schenk et al., 2004).

At thermal degradation stage (100 ~ 150 DEG C), liquefied hydrocarbon is more stable, but not the instability thought in the past and have the process resolving into methane and pyrobitumen gradually, if naphthenic hydrocarbon is in the thermal degradation stage, it is still very stable to reach tens years.And in higher temperature (150 ~ 190 DEG C) stage, can there is cracking into gas (Mango, 1991) in high-molecular weight hydrocarbon.Crude oil starts cracking occurs at 160 DEG C, between 170 ~ 195 DEG C, produces white oil and moisture (Ping et al., 2010).A Deep Reservoirs in the middle part of U.K. North Sea shows that the crude oil of reservoir inside is at 174 DEG C, even up to cracking (Pepper et al., 1995) does not occur when 195 DEG C.

Under geologic condition, the crude oil that Marine Carbonate Rocks hydrocarbon source rock generates is 150 DEG C time, and beginnings thermal cracking is generated a large amount of rock gas, and when temperature reaches 220 DEG C, cracking anger terminates substantially, and rock gas just all replaces oil; The generation Easy%Ro of methane is mainly between 1.2 ~ 2.9, and the generation Easy%Ro of C2-C5 hydrocarbon gas mainly between 1.5 ~ 2.5 (Geng Xinhua etc., 2008).Crude oil pyrolysis anger is divided into 3 stages: stabilization of crude oil stage, Oil Cracked Gas generate and the Oil Cracked Gas second pyrolysis stage for the first time.Easy%Ro value corresponding when crude oil starts cracking is about 1.20%, and along with the increase of degree of ripeness, oil lightens, to about 1.70% ~ 1.75% time conversion ratio reach about 51% ~ 62%, independent phase crude oil disappears, and starts to enter white oil and moisture stage; Crude oil is converted into Easy%Ro value corresponding to rock gas completely about 2.40%, and now pyrolysis gas output is maximum, but C1/C1 ~ 3 ratio is about 0.5, belongs to moisture and hides; After this, moisture starts second pyrolysis occurs, and methane is formed in a large number, enters the dry gas stage (Tian Hui etc., 2006).

Under different medium condition, the generation Activated factor Ⅶ of methane is variant, and carbonatite has the greatest impact to oil-breaking condition, can greatly reduce its energy of activation, causes crude oil pyrolysis thermal conditions to reduce, is presented as the reduction of oil-breaking temperature; Mud stone takes second place, and sandstone impact is minimum.The catalytic pyrolysis effect to oil of carbonatite, mud stone and sandstone weakens successively, the Ro value that under different medium condition, the main angry phase is corresponding: pure crude oil 1.5% ~ 3.8%; Dispersion crude oil 1.2% ~ 3.2% in carbonatite; Dispersion crude oil 1.3% ~ 3.4% in mud stone; ; Dispersion crude oil 1.4% ~ 3.6% in sandstone.Therefore, under different medium condition, crude oil pyrolysis temperature range also has different (Zhao Wenzhi etc., 2006).

Table 1

Bury to known oil reservoir in the world the statistics display that temperature does, most of oil is present in the temperature range of 65.5 ~ 149 DEG C, and after reservoir temperature is higher than 200 DEG C, rock gas just all replaces oil, therefore said temperature scope is called " oil window ".

The Well Tashen-1 of the western Tarim Basin of China is at buried depth 8404 ~ 7406m, and temperature 160, has found under the environment of pressure 80MPa in tawny liquid hydrocarbon.In well depth 8406.4m(5 ~ 14/27) and 8407.35m(5 ~ 19/27) in pierite solution cavity, soak through about 30 minutes clear water, and after chloroform solvent dissolves, collect liquid hydrocarbon be respectively about 10mL (Zhai Xiaoxian etc., 2007).

The achievement in research of above achievement in research and some other researcher is summarized in table 1.

Comprehensive above achievement in research, at high temperature there is cracking in crude oil, the initial temperature that cracking occurs controls (Price, 1993 by factors; Behar et al., 1996; Schenk et al., 1997), generally between 150 DEG C ~ 180 DEG C, the maximum temperature that crude oil is preserved is at 200 DEG C ~ 225 DEG C.As shown in Figure 2, above data are thrown on scatter diagram, can clearly be seen that: the initial temperature of crude oil pyrolysis anger is roughly 160 DEG C, the maximum temperature that crude oil pyrolysis anger terminates is approximately 210 DEG C, therefore, for the ease of calculating, it is 160 ~ 210 DEG C that embodiments of the invention get crude oil pyrolysis temperature window.

Fig. 3 is the process flow diagram of the sub-step that evolution recovering step in hydrocarbon source comprises.In one preferred embodiment, evolution recovering step in step S101 hydrocarbon source can comprise following sub-step:

Step S1011, utilizes the time of reservoir temperature history and cracking temperature window method determination Foregone pool reservoir cracking anger;

Particularly, utilize buried history and Thermal history to calculate the palaeotemperature of Foregone pool reservoir in earth history period, then palaeotemperature is contrasted with the crude oil pyrolysis temperature window of being determined by sample experiments data, determine the time of Foregone pool cracking anger;

As mentioned above, analyze the experimental data of forefathers about crude oil pyrolysis temperature by compiling, the cracking temperature window of having determined crude oil is 160 ~ 210 DEG C;

Step S1012, utilizes paleostructural map and palaeogeothermal figure to obtain the temporal-spatial evolution process of Foregone pool cracking hydrocarbon kitchen;

Particularly, utilize the locus of paleostructural map determination geology period of history Foregone pool cracking hydrocarbon kitchen, establishment palaeogeothermal figure determination Foregone pool is in the palaeotemperature in earth history period, the time of described Foregone pool cracking anger is obtained in conjunction with described crude oil pyrolysis temperature window, and the dynamic migration process of described Foregone pool cracking hydrocarbon kitchen;

It should be noted that, in the present embodiment, the time of Foregone pool cracking refers to the time of the crude oil pyrolysis in Foregone pool reservoir, when Foregone pool generation cracking is angry, is called cracking hydrocarbon kitchen; The temporal-spatial evolution of cracking hydrocarbon kitchen had both comprised the time of crude oil pyrolysis anger, also comprised the transition of cracking hydrocarbon kitchen in geologic epoch locus;

District is pointed in the favourable migration being early stage oil due to palaeohigh, and palaeohigh controls the distribution of Foregone pool, and paleostructural map can disclose the locus of palaeohigh, that is the distribution of Foregone pool cracking hydrocarbon kitchen.The preparation method of paleostructural map is conventional method, need not describe in detail;

The preparation method of palaeogeothermal figure is as follows: based on a large amount of drilling well and artificial well data, recovers on basis at basin palaeo-heat flow, in conjunction with buried history, calculates the temperature history on reservoir top circle and end circle, adopts method of interpolation establishment palaeogeothermal isoline planimetric map.Like this, paleostructural map discloses the position of earth history Foregone pool in period cracking hydrocarbon kitchen, palaeogeothermal figure discloses the palaeotemperature of Foregone pool reservoir in earth history period, the two is superimposed, again in conjunction with crude oil pyrolysis temperature window, can determine that the Foregone pool controlled by palaeohigh is in the angry state of cracking in earth history period, discloses the crucial moment of oil gas conversion and the dynamic migration feature of crude oil pyrolysis hydrocarbon kitchen.

Fig. 4 is the process flow diagram of the sub-step that Enclosing capability evolution recovering step comprises.In one preferred embodiment, step S201 Enclosing capability evolution recovering step can comprise following sub-step:

Step S2011, in the construction phase, utilizes factor of porosity-replacement pressure history method to recover the forming process of construction phase shale Enclosing capability;

The formation porosity that the present embodiment is mentioned refers to stratum total porosity.Total porosity reflects the compaction of mud stone.Formation porosity develops very complicated, by many factors, as diagenesis epigenetic changes, secondary porosity, low compaction, tectonic movement, uplift erosion, and tectoclase etc.In simulation process, to consider that the effect of each factor in porosity evolution is almost impossible comprehensively.For shale cap rock, burying compaction is the topmost factor affecting factor of porosity change, and diagenesis epigenetic changes is relatively weak on the impact of factor of porosity, and therefore, this research is only considered to bury the impact of compaction on porosity evolution.

The factor of porosity of petroclastic rock reduction gradually with the increase of the degree of depth when normal compaction, the die-away curve of sand shale factor of porosity is approximate follows exponential distribution:

φ=φ ₀e ^-cZ（ ₁）

By burial history reconstruction, mudstone porosity Evolutionary History can be calculated:

φ(Z,t)=φ ₀e ^-cZ（2）

Because the compaction coefficient of different lithology is different, the compaction coefficient difference such as between sandstone and mud stone is very large.Different times stratum is often made up of different kinds of rocks, even may comprise petroclastic rock and carbonatite simultaneously.Under the complex lithology condition that stratum is made up of different kinds of rocks, formation porosity can be improved to change in depth relational expression:

$\mathrm{\φ}(Z,t)=P_1{\mathrm{\φ}}_1{e}^{-c_{1}Z}+P_2{\mathrm{\φ}}_2{e}^{-c_{2}Z}+P_3{\mathrm{\φ}}_3{e}^{-c_{3}Z}+...+P_n{\mathrm{\φ}}_n{e}^{-c_{n}Z}---\left(3\right)$

In formula, wherein, φ (Z, t) is at Geologic Time t, factor of porosity when buried depth is Z;

P ₁, P ₂, P ₃..., P _n, be formation lithology percentage composition;

φ ₁, φ ₂, φ ₃..., φ _n, be corresponding lithology sediment initial porosity;

C ₁, c ₂, c ₃..., c _n, be corresponding lithology compaction coefficient;

Z represents the buried depth of Geologic Time t, and Z is the variable changed with Geologic Time t.

The then replacement pressure history of construction phase cap rock:

P _c(Z,t)＝fφ(Z,t)=f(φ0e ^-cZ) （4）

Funtcional relationship f can survey replacement pressure by sample and porosity data the Fitting Calculation obtains.

In formula (1), (2), (3) and (4): φ and φ ₀be respectively formation porosity and the earth's surface factor of porosity at degree of depth Z place, unit is %; Z is the degree of depth, and unit is m; C is formation physical parameters, is equivalent to compaction coefficient, and unit is 1/m.φ (z, t) is namely at Geologic Time t(Ma), buried depth is Z(m) time factor of porosity (%); P _c(Z, t) i.e. Geologic Time t(Ma), buried depth is Z(m) time replacement pressure (MPa).

Experimental data shows, and there is obvious correlativity between formation porosity and replacement pressure.Total porosity is less, and compaction is higher, and pore constriction radius is less, and mud stone hole capillary force is larger, and permeability is lower, and replacement pressure is larger, and closed performance is better.Therefore, mud shale cap rock total porosity is the important parameter of reflection closed cap quality.

Fig. 5 is rock replacement pressure and the total porosity graph of a relation of lab analysis test.As can see from Figure 5, total porosity of shale and replacement pressure are that nonlinear function changes.The relational expression of factor of porosity and replacement pressure is obtained according to the 120 pairs of factor of porosity-replacement pressure data fitting collected:

P _c(Z,t)=24.799×φ(Z,t) ^-0.8189（5）

In formula, P _c(Z, t) is replacement pressure, MPa; φ (Z, t) is stratum total porosity, %.

Hereto, in embodiments of the invention, introduce the concept of Geologic Time, calculate old Jun procelain by the ancient buried depth of different times, thus obtain the evolutionary process of burying stage factor of porosity.The relation of foundation factor of porosity and replacement pressure again, calculates replacement pressure history by factor of porosity history, thus recovers the forming process that shale cap rock buries stage closure.

Step S2012, at alteration stage, utilizes permeability-replacement pressure history method to recover the replacement pressure Evolutionary History of shale cap rock in lifting process;

In tectonic reworking process, as uplift erosion, stratum release effect, makes the supracrustal rocks of original buried underground to produce microfracture, causes permeability to increase, and replacement pressure reduces.How obtaining the relation between replacement pressure and stratum release, is the key of Enclosing capability dynamic evolution in research tectonic reworking process.Existing test data analysis shows, in uplift erosion process, as shown in Figure 6 a, the factor of porosity of supracrustal rocks is little with confined pressure change; As shown in Figure 6 b, in close relations between permeability and confined pressure.Therefore, do not considering that other complicated factors such as rupture failure effect are in the sex situation of closed cap, the replacement pressure history of alteration stage can be used: P _c(Z, t)=fK (Z, t) asks for.K (Z, t) is namely at Geologic Time t(Ma), buried depth is Z(m) time permeability (millidarcy).By cap rock permeability data under the confined pressure condition of test analysis stratum, ask for the correlationship between permeability and confined pressure, again confined pressure is associated with uplift and erosion amount, just can obtain the Evolution of replacement pressure in uplift and erosion process, thus obtain and grandly rise alteration stage Enclosing capability Evolutionary History.

Further experimental data shows, there is obvious correlativity between shale cap rock permeability and confined pressure.As shown in Figure 7, under logarithmic coordinate system, the permeability of shale cap rock increases with the reduction of confined pressure.

Under identical release condition, the mud stone of different original permeability, final permeability is also different.Permeability after the complete release of the mud stone that under high confining pressure, permeability is higher is also higher, the mud stone that under high confining pressure, permeability is lower, and the permeability after complete release is also lower.Obvious correlativity is there is between the knots modification of visual penetration rate and the knots modification of confined pressure.

As shown in Figure 8, under linear coordinate system, the mud stone that original permeability is larger, under identical confined pressure loading environment, permeability variation is also comparatively large, and the mud stone that original permeability is less, permeability variation is less.Visible, load with under release condition in identical confined pressure, the change of permeability is relevant with original permeability.

Shale cap rock permeability changes with the change of confined pressure, and confined pressure increases, permeability reduction, and in stress-relief process, permeability increases.Found by further investigation: in pressurization, stress-relief process, between the knots modification of shale cap rock permeability and the knots modification of confined pressure, there is following funtcional relationship:

△K _P=-0.2K ₀×ln(△P)-0.2K ₀（6）

In formula, △ K _pfor the knots modification of permeability, mD; △ P is the knots modification of confined pressure, MPa; K ₀for original permeability (permeability under normal pressure), mD.

Therefore, as long as know original permeability, the knots modification of confined pressure, can obtain the permeability under the knots modification of permeability and different confined pressure.

As shown in Figure 9, original permeability K ₀can be calculated by factor of porosity-Permeability fit relation.By the factor of porosity-permeability data pair of 137 samples, under logarithmic coordinate system, draw scatter diagram, matching obtains permeability-factor of porosity correlationship formula:

K(Z,t)=exp[0.5147×φ(Z,t)]×0.00594 （7）

K (Z, t) is at Geologic Time t(Ma), buried depth is Z(m) time permeability, mD.

The knots modification △ P of confined pressure can be calculated by uplift and erosion gauge and obtain, that is:

△P=0.010133×(ρ _r-ρ _w)×△Z

△ P is confined pressure knots modification, MPa; △ Z is denudation, m; ρ _rand ρ _wbe respectively the density of rock and local water, g/cm ³.

Thus shale cap rock permeability evolution history in uplift processes can be obtained.Based on the measured data data of 141 shale cap rock samples, under logarithmic coordinate system, replacement pressure linearly changes (Figure 10) with permeability, and data fitting obtains the correlationship formula between replacement pressure and permeability:

P _c(Z,t)=0.253×K(Z,t) ^-0.747（8）

In formula: P _c(Z, t) is at Geologic Time t(Ma), buried depth is Z(m) time replacement pressure, MPa; K (Z, t), at Geologic Time t(Ma), buried depth is Z(m) time permeability, mD.

Visible, in power exponential function relation between replacement pressure and permeability, coefficient R ²up to 0.919.

According to formula (6), (7) and (8), the replacement pressure Evolutionary History of shale cap rock in lifting process can be recovered.

Hereto, establish the funtcional relationship between the variable quantity of mud shale confined pressure and permeability variation amount and the funtcional relationship between replacement pressure and permeability, and introduce the function of time, recover the history of evolution of cap rock replacement pressure in lifting.

Step S2013, adopts over-consolidation ratio OCR history standard measure to constrain in the closure evolutionary process of shale cap rock in lifting process;

In clay mechanics, through conventional over-consolidation ratio OCR(overconsolidation ratio) parameter comes plasticity and the fragility of quantitative description clay.In rock mechanics, to be in buried depth process always, later stage never suffers mud stone when constructing lifting transformation to be called NC(normal consolidation) mud stone, if mud stone is called OC(overconsolidation after being raised to the shallow even earth's surface of the earth's crust from the maximum buried depth in earth history period) mud stone.Continue the NC mud stone of buried depth and have plastic behavior, the NC mud stone suffering lifting release is fragility by plastic deformation gradually, becomes OC mud stone.

Plastic shale is different with the deformational behavior of fragile shale generation shear failure.When shear stress is greater than shear resistance, rock generation shear failure.But not all shear failure all forms shearing crack.Whether shearing crack is formed, also relevant with plasticity with the fragility of rock.During fragile shale generation shear failure, form crack, and produce diffusion deformation during plastic shale generation shear failure.During fragile shale generation shear fracture, along with the increase of detrusion, permeability increases; During plastic shale generation shear failure, along with the increase of distortion, permeability reduction.Because the former shows as expansion and momentary breakdown, and the latter shows as compression deformation.Thus the mud stone of different fragility and plasticity closes the ability also complete difference of oil gas in the tectonic reworking process in later stage.

From the thin angle seen, adopt OCR(overconsolidation ratio) the grand closure dynamic evolution risen in transformation, stress-relief process of history standard measure constraint cap rock.In earth history period, the maximum perpendicular effective pressure that mud stone experiences is called precosolidation pressure (pre-consolidation stree) σ ' _vmax, unit is MPa.For NC mud stone, vertical effective pressure σ ' now _v(MPa) maximum perpendicular effective pressure σ ' is _vmax; For OC mud stone, vertical effective pressure σ ' now _v(MPa) maximum perpendicular effective pressure is less than.In clay mechanics, OCR is defined as maximum perpendicular effective pressure σ ' _vmax(MPa) with vertical effective pressure σ ' now _v(MPa) ratio, that is:

OCR=σ' _vmax/σ' _v(9)

The precondition of above OCR parameter definition does not consider tectonic stress effect, and maximum perpendicular effective pressure is maximum principal effective stress, and horizontal direction effective pressure is minimum principal effective stress.

Parameter OCR can reflect the degree of brittleness of mud stone.OCR is larger, and the fragility of high evolution mud stone is also larger.The OCR value that the OCR of NC mud stone equals 1, OC mud stone is greater than 1, and along with the increase of uplift erosion amplitude, OCR increases gradually, and after OCR increases to certain value, mud stone breaks, thus loses the ability of closed rock gas completely.

The introducing of rill evolution over-consolidation ratio OCR, evaluates significant to alteration stage Enclosing capability., easily there is non-plastic fracture, thus lose closure in the mudstone caprock of experience later stage uplift erosion, release transformation.Such as, the earth's surface shale cap rock that outcrop is observed, usually can observe fracture development phenomenon; The mud stone core taken out from down-hole, also usually chipping phenomenon, the pelyte of fracture development all loses the ability of closed rock gas.But no matter be surface occurence sample or down-hole core sample, usually avoid fracture developing zone during collection, their replacement pressure test data of experiment is often very high, demonstrates the closure of high-quality.Like this, there is the contradiction that test data of experiment and actual conditions are not inconsistent.The introducing of mud stone over-consolidation ratio OCR parameter, can solve this contradiction preferably, compensate for the deficiency of the Pc of replacement pressure parameter.

When not considering abnormal pore fluid pressure, between vertical effective pressure and buried depth, there is following relation:

σ _vmax=0.010133×(ρ ₁-ρ _w)×Z ₁（10）

σ _v=0.010133×(ρ ₂-ρ _w)×Z _t（11）

$\mathrm{OCR}(Z,t)=\frac{{{\mathrm{\σ}}^{\′}}_{v\max }}{{{\mathrm{\σ}}^{\′}}_v}=\frac{({\mathrm{\ρ}}_1-{\mathrm{\ρ}}_w)\×Z_1}{({\mathrm{\ρ}}_2-{\mathrm{\ρ}}_w)\×Z_t}---\left(12\right)$

In formula:

σ ' _vmaxfor the maximum perpendicular effective pressure that mud stone experiences, σ ' _vfor buried depth is Z _tvertical effective pressure, ρ ₁for stratigraphic rock density during maximum buried depth, ρ ₂for buried depth is Z _tburied depth time rock density, ρ _wfor local water density, Z ₁for maximum buried depth, Z _tfor the ancient buried depth in lifting process.

Do not considering (as regional lateral extrusion stress causes stratum deformation and the factor such as fold, fracture) under tectonic stress effect, when only considering uplift erosion, this factor of stratum release, when OCR is greater than (equaling) 2.5, mud stone breaks, thus lose closure (Nygard et al., 2006).Therefore, can judge whether non-plastic fracture occurs in shale cap rock lifting process by OCR history, whether lose the ability of closed oil gas.

embodiment two

For area, Weiyuan, Sichuan Basin prestige 28 well, the beneficial effect of the method for preferred oil gas exploration zone of the present invention is described.

Figure 11 and Figure 12 is that area, Weiyuan prestige 28 well is in step S101, raw hydrocarbon history result of calculation in hydrocarbon source evolution recovering step: oil generation phase of prestige 28 well Lower Cambrian Series Niutitang group hydrocarbon source rock be Early Permian Epoch-late Triassic epoch, the kerogen main angry phase be Early Jurassic Epoch-Paleocene epoch, the dispersion hydrocarbon pyrolysis angry phase be Middle Jurassic epoch-Oligocene epoch.Oil generation phase of Lower Permian Series hydrocarbon source rock be Middle Triassic epoch-Early Creataceous Epoch, the kerogen main angry phase be Early Creataceous Epoch-Oligocene epoch, the dispersion hydrocarbon pyrolysis angry phase be the Paleocene epoch-Oligocene epoch.

Figure 13 is the angry history figure of area, Weiyuan prestige 28 well Sinian system Foregone pool cracking.With prestige 28 well Sinian system reservoir for research object, on the basis of Thermal history, in conjunction with buried history, calculate the temperature history of reservoir.As seen from Figure 13, at the bottom of prestige 28 well Sinian system reservoir, boundary reaches 160 DEG C in late Triassic epoch temperature, top circle temperature is reaching 210 DEG C in the Eocene era, determine thus: the angry start time of the crude oil pyrolysis in prestige 28 well Sinian system Foregone pool is late Triassic epoch (~ 235Ma), and the time upper limit that cracking anger terminates is the Eocene era (38Ma).

Figure 14 is prestige 28 down-hole Palaeozoic caprocks buried history, discloses: Weiyuan structure prestige 28 well Cambrian system cap rock, southwest, river (∈ 1n) and Ordovician system Meitan group cap rock (O ₁m) experienced by lifting by a relatively large margin at Caledonian, Silurian is all degraded, until the Permian period just sedimentation buried depth again again, Indosinian movement experienced by of short duration lifting and degrades by a small margin, after this, be in deposition for a long time and bury process, until just again experience lifting process time Neogene Period Oligocene epoch end (~ 23.3Ma), and after this there is no sedimentation and buried depth again again.In step S102, in Enclosing capability evolution recovering step, in the construction phase, factor of porosity-replacement pressure history method is utilized to recover the forming process of construction phase shale Enclosing capability.

As can be seen from Figure 15, to Paleozoic Era Mo after prestige 28 well Cambrian system cap rock (bottom) auto-deposition, factor of porosity is reduced to 15.6% by initial porosity 59.6%; During Neopaleozoic, owing to being in uplift erosion process, factor of porosity remains unchanged; The Permian period-early-middle Cambrian factor of porosity reduces fast, and end of the Early Triassic factor of porosity is down to 8.5%, and Middle Triassic epoch end is down to 7.0%; Late Triassic epoch-Oligocene epoch during factor of porosity slowly reduce, Oligocene epoch end (23Ma), factor of porosity stop continue reduce, be down to minimum (1.77%).Ordovician system Meitan group shale cap rock (O ₁m) have the porosity evolution history basically identical with Cambrian system Niutitang group cap rock (∈ 1n), Silurian last factor of porosity is down to 27.3%, and Middle Triassic epoch end is down to 10.9% respectively, the Oligocene epoch Mo factor of porosity be 2.3%.

At alteration stage, permeability-replacement pressure history method is utilized to recover the replacement pressure Evolutionary History of shale cap rock in lifting process, as can be seen from Figure 16, the replacement pressure of bottom, area prestige 28 well Lower Cambrian Series shale cap rock, Weiyuan, southwest, river (∈ 1n) is 1.4MPa in Cambrian period Mo, possesses oil sealing ability, be greater than 5MPa at end of the Early Triassic, possess closed rock gas ability; To Middle Triassic epoch Mo, replacement pressure is greater than 10MPa, can seal PRESSURE GAS RESERVOIR; Mid-term in Early Creataceous Epoch, replacement pressure reached 15MPa, can seal UHV (ultra-high voltage) gas reservoir, and Oligocene epoch end reaches maximal value (20.5MPa).Since the Oligocene epoch, due to lifting release effect, cap rock replacement pressure reduces, and Neogene Period end replacement pressure is down to 13.5MPa, from the angle evaluation of this micro-parameter of replacement pressure, prestige 28 well Lower Cambrian Series shale cap rock still possesses the ability (Figure 16) of closed PRESSURE GAS RESERVOIR now.

The another set of shale cap rock of prestige 28 well is Ordovician system Meitan group mud shale.Ordovician system Meitan group shale cap rock (O ₁m) late period in late Triassic epoch replacement pressure reach 5MPa, start to possess closed rock gas ability; Latter stage late Jurassic epoch replacement pressure reach 10MPa, can PRESSURE GAS RESERVOIR be sealed; Reach 15MPa at Latest Cretaceous replacement pressure, UHV (ultra-high voltage) gas reservoir can be sealed; To Oligocene epoch Mo, replacement pressure reaches maximal value (17.4MPa).Since the Oligocene epoch, due to lifting release effect, cap rock replacement pressure reduces, and Neogene Period end replacement pressure is down to 10.9MPa, from the angle evaluation of this micro-parameter of replacement pressure, prestige 28 well Ordovician system Meitan group shale cap rock still possesses the ability (Figure 16) of closed PRESSURE GAS RESERVOIR now.

In a subsequent step, over-consolidation ratio OCR history standard measure is adopted to constrain in the closure evolutionary process of shale cap rock in lifting process.Southwest, the river Weiyuan area lifting time in late period is more late, and Oligocene epoch end, (23Ma) just started uplift erosion, and prestige 28 well erosion sediment thickness is 2889m.Buried depth during prestige 28 well Lower Cambrian Series Niutitang group Oligocene epoch Mo is 5868.5m, is now NC mud stone, OCR=1; Buried depth is 2980.5m now, is transformed into OC mud stone, OCR=1.799, not yet reaches threshold value 2.5 of breaking.Meitan group cap rock buried depth 2112m, OCR=2.248 now, also not yet reaches threshold value 2.5 of breaking.Therefore, from the thin angle seen, the prestige 28 down-hole Paleozoic erathom two overlaps shale cap rock, and after experience lifting release, all not yet break (Figure 17 a, Figure 17 b).From microcosmic angle, before set forth, this two covers mud stone pressure is now respectively 13.5MPa and 10.9MPa, has the ability of closed PRESSURE GAS RESERVOIR.

Associating rill evolution OCR and micro-parameter replacement pressure comprehensive evaluation, it is good that the prestige 28 down-hole Paleozoic erathom two overlaps shale cap rock Dynamic Closed performance.

In step S103, in the lid matching judgment step of source, judge formation time and the precedence relationship of underlie hydrocarbon primary rock producing hydrocarbon time and Foregone pool cracking angry time of prestige 28 well Enclosing capability.The Weiyuan area Paleozoic hydrocarbon source rock in prestige 28 down-hole mainly Lower Cambrian Series Niutitang group (Bamboo Temple group) black shale.The oil gas that Lower Cambrian Series Bamboo Temple group dark mud rock generates enters Sinian system crust reservoirs of weathering Aggregation indica by unconformity surface side direction.Sinian system lamp four, lamp three sections of pierites are main payzone.Steep mountain of uniting of lower shake dawn sticks together group hydrocarbon source rock in the agensis of palaeohigh region, and therefore, comparatively speaking, four sections, lamp is more conducive to accepting the oil gas from above covering Bamboo Temple group hydrocarbon source rock and generating than three sections, lamp and two sections, lamp, and the probability of Aggregation indica is higher than lamp three, two sections, lamp.The Sinian system aerogenesis interval found so far is mainly on four sections, lamp and lamp three sections of tops, and the phenomenon that bottom product water increases is exactly an illustration (Wei state is neat, 2010).Lower Cambrian Series Bamboo Temple group hydrocarbon source rock is at thick about the 300m in area, Weiyuan, and organic carbon average content 2%, be sapropelic organic matters, evolution level is higher.Reservoirs of Dengying Formation generally grows pitch.According to Zhang Lin (2005) statistics, the dark 1 well pitch average content of nest of geotectogene is 0.41%; What be positioned at slope belt is 1.13% from dark 1 well pitch average content, and prestige 117 well is 0.93%; In palaeohigh core portion, pitch average content is the highest with female Ji Jing, reaches 8.12%, and Anping 1 well is 2.40%, and high-tech 1 well is 5.41%, and providing 2 wells is 5.29% (Zhang Lin etc., 2005).Show at paleo-uplift region, Sinian Dengying group once grew fairly large Foregone pool, according to Sun Wei (2007) estimation, once formed 17 × 10 within the scope of Ziyang-area, Weiyuan 1900km ⁸the Foregone pool of t, Foregone pool cracking forms ancient gas reservoir, and the original cracking tolerance of ancient gas reservoir can reach 10576 × 108m ³(Sun Wei etc., 2007).

Prestige 28 well lid layer is Lower Cambrian Series Niutitang group (Bamboo Temple group) and Lower Ordovician Series Meitan group (point township's group) shale cap rock mainly, and thickness is respectively 433.5m and 165.5m.Also grow certain thickness middle upper Cambrian series containing cream laccolith layer, but it be unclear that due to gypsum-salt rock Enclosing capability dynamic evolution mechanism, this does not relate to its dynamic evolution history and recovers.

Recovered by raw hydrocarbon history and cap rock replacement pressure history, the formation time of prestige 28 well Enclosing capability is early than underliing hydrocarbon primary rock producing hydrocarbon time and Foregone pool cracking angry time.The oil generation phase of Niutitang group (Bamboo Temple group) hydrocarbon source rock is Permian-triassic, and the kerogenic main angry phase is Jurassic and Cretaceous, the Sinian system Foregone pool cracking angry phase be late Triassic epoch-Eocene era.And Lower Cambrian Series Niutitang group shale cap rock just can oil sealing in Cambrian period Mo, just possesses the ability of closed rock gas, once once possessing the ability of closed UHV (ultra-high voltage) gas reservoir to the early Triassic Epoch.Since the Oligocene epoch, although cause replacement pressure to decrease because of lifting release effect, replacement pressure is still greater than 10MPa now, possesses the ability of closed PRESSURE GAS RESERVOIR.And in lifting transformation process since the Oligocene epoch, OCR value is less than threshold value 2.5 of breaking, and OCR is 1.799 now, not yet non-plastic fracture occurs, therefore, unanimously since closure self-forming to have kept so far (Figure 18).

Prestige 28 well Ordovician system Meitan group shale cap rock can oil sealing at latest Ordovician, starts to possess closed rock gas ability in late period in late Triassic epoch.Since the Oligocene epoch, due to lifting release effect, cap rock replacement pressure reduces, and Neogene Period end replacement pressure is down to 10.9MPa, but still possesses the ability of closed PRESSURE GAS RESERVOIR now.And in transformation process since the Oligocene epoch, OCR value is less than threshold value 2.5 of breaking, and OCR is 2.248 now, not yet breaks, therefore, unanimously since closure self-forming to have kept so far.Visible, having good Dynamic Matching relation between prestige 28 down-hole Palaeozoic Source Rock and cap rock, is the source lid dynamic evolution part being conducive to Hydrocarbon Formation Reservoirs.

the efficiency analysis of result of calculation

By force, superior hydrocarbon preservation environment is defined just because of area Lower Cambrian Series Niutitang group, Weiyuan (Bamboo Temple group) and Lower Ordovician Series Meitan group (point township's group) shale Enclosing capability.Weiyuan and area, Ziyang drilling stratum water chemistry property show, this area's Conservation environment is good, and Sinian system is in local water and replaces zone of stagnation.In the Sinian system local water sample of 17 mouthfuls of prospect pits, the week public 1 well salinity being only positioned at pelvic floor hernia is low, for 0.743g/L, and Metamorphic Coefficient high (up to 3.4), Su Lin classification water type is bicarbonate sodium form, the Sinian system reservoir water salinity of all the other drilling wells is very high, be generally 60 ~ 80g/L, Metamorphic Coefficient is lower, is generally less than 1.0, close to or the Metamorphic Coefficient (0.87) of a little higher than normal seawater, Su Lin water type of classifying is chloride-calcium type (Figure 19).

Owing to experienced by the uplift erosion of paulownia gulf phase after Denying Formation deposition, area, Weiyuan on a large scale in lamp four sections of Local residues, Ziyang paleotrap is except money 1 well lamp four bottom is residual, all the other prospect pits are all degraded to three sections, lamp, form palaeokarst geomorphologic landscape, metrical water infiltrates the primary pore water making the seawater origin cause of formation and was once once transformed by desalination, therefore, and the Metamorphic Coefficient of a little higher than connate formation water of Metamorphic Coefficient.After the motion of paulownia gulf, Lower Cambrian Series mud stone covers on it, and under compaction, Lower Cambrian Series pore water must add in Denying Formation pore layer and Fracture-cavity system.Along with buried depth strengthens, ground temperature rise, Lower Cambrian Series organic matter generates oil gas and migrates in Denying Formation Reservoir Body downwards, the a large amount of organic acids produced in oil-gas generation process also migrate in Denying Formation Reservoir Body thereupon, under organic acid effect, local water and the interaction of country rock generation water petrofacies, make hole better be transformed, be conducive to preserving of oil gas.Along with the continuation of buried depth strengthens, the continuous rising of ground temperature, pore water is in relative dead state, and the metamorphism of main generation evaporation and concentration, makes the salinity of local water constantly raise (Yang Jiajing, 2002).Added that the closure of Cambrian system cap rock is since Cambrian period Mo is formed, replacement pressure constantly increases, and keeps for a long time, not yet destroys so far, prevents overlying strata water and metrical water to enter.Therefore, Sinian system reservoir formation water shows as high salinity, and water type is chloride-calcium type feature, reflects the Conservation environment of high-quality.

Visible, the source lid matching relationship of area, Weiyuan prestige 28 Jing Gongyeqiliujing is good.The formation time of Lower Paleozoic strata regional caprock closure is early than the hydrocarbon generation time of hydrocarbon source rock and Sinian system Foregone pool cracking angry time, and closure keeps not wrecking so far always, possesses Dynamic Closed validity.

In 107 mouthfuls of drilling wells of area, Weiyuan probing, the gas well that daily gas is greater than 10,000 sides has 72 mouthfuls, and prestige 28 well is one of them.Visible, according to the assessment technique method of this patent, to the evaluation result of prestige 28 well Enclosing capability and source lid Dynamic Matching relation, match with actual oil-gas exploration result.

Although the embodiment disclosed by the present invention is as above, the embodiment that described content just adopts for the ease of understanding the present invention, and be not used to limit the present invention.Technician in any the technical field of the invention; under the prerequisite not departing from the spirit and scope disclosed by the present invention; any amendment and change can be done what implement in form and in details; but scope of patent protection of the present invention, the scope that still must define with appending claims is as the criterion.

Claims (8)

1. a method for preferred oil gas exploration zone, is characterized in that: comprising:

Hydrocarbon source evolution recovering step, recovers the raw hydrocarbon history of hydrocarbon protolith kerogen, utilizes the time of reservoir temperature history and cracking temperature window method determination Foregone pool cracking anger, and adopts paleostructural map and palaeogeothermal figure method to obtain the temporal-spatial evolution process of Foregone pool cracking hydrocarbon kitchen;

Enclosing capability evolution recovering step, in the construction phase, utilizes factor of porosity-replacement pressure history method to recover the forming process of construction phase shale Enclosing capability; At alteration stage, utilize permeability-replacement pressure history method to recover the replacement pressure Evolutionary History of shale cap rock in lifting process, adopt over-consolidation ratio OCR history standard measure to constrain in the closure evolutionary process of shale cap rock in lifting process;

Source lid matching judgment step, covers the precedence relationship of the time of hydrocarbon protolith kerogen hydrocarbon generation time and Foregone pool cracking anger under judging the time that shale Enclosing capability is formed and described shale cap rock, determine whether cap rock is dynamic effectively cap rock in the geologic epoch.

2. the method for claim 1, is characterized in that: in described hydrocarbon source evolution recovering step, utilizes the time of reservoir temperature history and cracking temperature window method determination Foregone pool cracking anger to comprise:

Utilize buried history and Thermal history to calculate Foregone pool reservoir in the palaeotemperature in earth history period, palaeotemperature is contrasted with the crude oil pyrolysis temperature window of being determined by sample experiments data, determines the time of the crude oil pyrolysis anger in Foregone pool.

3. method as claimed in claim 2, it is characterized in that, in described hydrocarbon source evolution recovering step, the temporal-spatial evolution process utilizing paleostructural map and palaeogeothermal figure to obtain Foregone pool cracking hydrocarbon kitchen comprises:

Utilize the locus of paleostructural map determination geology period of history Foregone pool cracking hydrocarbon kitchen, establishment palaeogeothermal figure determination Foregone pool is in the palaeotemperature in earth history period, the time of described Foregone pool cracking anger is obtained in conjunction with described crude oil pyrolysis temperature window, and the dynamic migration process of described Foregone pool cracking hydrocarbon kitchen.

4. method as claimed in claim 3, is characterized in that, in described Enclosing capability evolution recovering step, in the construction phase, the forming process utilizing factor of porosity-replacement pressure history method to recover construction phase shale Enclosing capability comprises:

In the construction phase, calculate the old Jun procelain history of shale cap rock according to the ancient buried depth of geology period of history, described old Jun procelain history is: $\mathrm{\φ}(Z,t)=P_1{\mathrm{\φ}}_1{e}^{-c_{1}Z}+P_2{\mathrm{\φ}}_2{e}^{-c_{2}Z}+P_3{\mathrm{\φ}}_3{e}^{-c_{3}Z}+...+P_n{\mathrm{\φ}}_n{e}^{-c_{n}Z},$

Wherein, φ (Z, t) is at Geologic Time t, factor of porosity when buried depth is Z, P ₁, P ₂, P ₃..., P _nfor formation lithology percentage composition; c ₁, c ₂, c ₃..., c _nfor corresponding lithology compaction coefficient; Z is the buried depth of Geologic Time t; φ ₁, φ ₂, φ ₃..., φ _n, be corresponding lithology sediment initial porosity;

The variation relation between construction phase shale cap rock replacement pressure history and factor of porosity history is determined: P based on sample measured data _c(Z, t)=f φ (Z, t)=f (φ ₀e ^-cZ),

Wherein, P _c(Z, t) is Geologic Time t, replacement pressure when buried depth is Z, φ ₀for earth's surface factor of porosity, obtain funtcional relationship f by sample actual measurement replacement pressure and porosity data the Fitting Calculation;

According to construction phase shale cap rock replacement pressure history P _c(Z, t) recovers the forming process of closure.

5. method as claimed in claim 4, is characterized in that, in described Enclosing capability evolution recovering step, at alteration stage, utilizes permeability-replacement pressure history method to recover the replacement pressure Evolutionary History of shale cap rock in lifting process and comprises:

At alteration stage, set up the funtcional relationship △ K between the knots modification of shale cap rock permeability and the knots modification of confined pressure _p=-0.2K ₀× ln (△ P)-0.2K ₀, wherein, △ K _pfor the knots modification of permeability, △ P is the knots modification of confined pressure, K ₀for original permeability;

Experimentally data fitting obtains the funtcional relationship P between the replacement pressure history of alteration stage and permeability history _c(Z, t)=0.253 × K (Z, t)- ^0.747, wherein, P _c(Z, t) is Geologic Time t, replacement pressure when buried depth is Z, and K (Z, t) is Geologic Time t, permeability when buried depth is Z;

According to P _c(Z, t)=0.253 × K (Z, t)- ^0.747recover the replacement pressure Evolutionary History of shale cap rock in lifting process.

6. method as claimed in claim 5, it is characterized in that, the OCR parameter in described over-consolidation ratio OCR history method is

$\mathrm{OCR}(Z,t)=\frac{{{\mathrm{\σ}}^{\′}}_{v\max }}{{{\mathrm{\σ}}^{\′}}_v}=\frac{({\mathrm{\ρ}}_1-{\mathrm{\ρ}}_w)\×Z_1}{({\mathrm{\ρ}}_2-{\mathrm{\ρ}}_w)\×Z_t},$

Wherein, σ ' _vmaxfor the maximum perpendicular effective pressure that mud stone experiences, σ ' _vfor buried depth is Z _tvertical effective pressure, ρ ₁for stratigraphic rock density during maximum buried depth, ρ ₂for buried depth is Z _tburied depth time rock density, ρ _wfor local water density, Z ₁for maximum buried depth, Z _tfor the ancient buried depth in lifting process.

7. method as claimed in claim 6, it is characterized in that, in described Enclosing capability evolution recovering step, the closure evolutionary process utilizing over-consolidation ratio OCR parameter quantitative to constrain in shale cap rock in lifting process comprises:

When described over-consolidation ratio OCR parameter is greater than or equal to 2.5, shale cap rock breaks, and loses closure.

8. method as claimed in claim 7, it is characterized in that, in the lid matching judgment step of described source, when covering the time of hydrocarbon protolith hydrocarbon generation time and Foregone pool cracking anger under the formation time of shale Enclosing capability is early than described cap rock, described cap rock is dynamic effectively cap rock, and source lid matching relationship is the relation being conducive to Hydrocarbon Formation Reservoirs and preservation.