CN103926389A - Method for determining source rock free hydrocarbon discharge critical condition - Google Patents

Abstract

The present invention relates to a conception model of a free hydrocarbon discharge critical condition during a source rock evolution process, and a technical method for quantitatively determining the critical condition by adopting four parameters such as the hydrocarbon generation amount, the residual hydrocarbon critical saturation amount, the water-dissolving phase hydrocarbon discharge amount and the diffuse phase hydrocarbon discharge amount. According to the method, when the source rock hydrocarbon generation amount is more than the sum of the residual hydrocarbon critical saturation amount, the water-dissolving phase hydrocarbon discharge amount and the diffuse phase hydrocarbon discharge amount, it is indicated that the source rock enters the free hydrocarbons discharge critical condition; when source rock hydrocarbon generation amount is equal to the sum of the residual hydrocarbon critical saturation amount, the water-dissolving phase hydrocarbon discharge amount and the diffuse phase hydrocarbon discharge amount, it is indicated that the source rock is in the free hydrocarbons discharge critical condition, and the buried depth condition or the evolution degree corresponding to the source rock can characterize the free hydrocarbon discharge critical condition; and when the source rock hydrocarbon generation amount is less than the sum of the residual hydrocarbon critical saturation amount, the water-dissolving phase hydrocarbon discharge amount and the diffuse phase hydrocarbon discharge amount, it is indicated that the source rock does not enter the free hydrocarbon discharge critical condition. According to the present invention, with establishment of the conception model of the free hydrocarbon discharge critical condition and provision of the technical method, the defect of evaluation on source rock quality with the hydrocarbon generation threshold is overcome, and great theoretical technical significance is provided for objective evaluation on resource potential of the source rock and designation of the right oil and gas exploration direction.

Description

A kind of definite hydrocarbon source rock free hydrocarbon is discharged the method for critical condition

Technical field

The present invention relates to a kind of technical method in oil and gas resource evaluation field, a kind of definite hydrocarbon source rock that relates to specifically the magnitude relationship foundation that utilizes computing hydrocarbon generating quantity of source and residual hydrocarbons Critical saturation quantity, water-dissolving phase row's hydrocarbon amount and diffusion phase row hydrocarbon amount three sum starts to arrange in a large number the method for hydrocarbon critical geologic condition

Background technology

The widespread use in exploration of oil and gas field practice at present of raw this concept of hydrocarbon thresholding.It refers in organic matter evolution process and starts the critical geologic condition to oil gas conversion in a large number, generally represents with the vitrinite reflectance Ro in the organic matter under respective conditions.Under general geologic condition, the vitrinite reflectance Ro at hydrocarbon primary rock producing hydrocarbon threshold point place is 0.5%(Tissot B P, Welte D H. 1978. Petroleum Formation and Occurrence. Springer-Verlag.).After this concept proposes, some scholars differentiate source rock and non-source rock, determine that with it source rock starts the critical geologic conditions of giving birth in a large number the hydrocarbon phase and starting a large amount of row's hydrocarbon with it, with its divide ripe raw hydrocarbon rock scope and calculate hydrocarbon resources amount (the .1986. oil source rock pyrolysis rapid quantitatively evaluating such as Wu Liyan. Beijing: Science Press .).

Raw hydrocarbon thresholding is organic transforming degree index, if be not combined with abundance of organic matter and type, it can not reflect the raw hydrocarbon amount of source rock, can not reflect row's hydrocarbon amount of source rock.Critical Standard with it as source rock row hydrocarbon can be met difficulty in theory and in fact all.

Raw hydrocarbon thresholding only shows the transforming degree of source rock, does not show raw hydrocarbon amount size.Do not consider the impact of hydrocarbon primary rock producing hydrocarbon factor as row's hydrocarbon critical geologic condition of source rock with raw hydrocarbon thresholding.Vitrinite reflectance is the scale of hydrocarbon source rock transforming degree.Hydrocarbon source rock transforming degree is high again, if do not contained, organic matter can not be given birth to, oil extraction gas.Hydrocarbon source rock is containing organic, if but abundance is low or type is poor especially can not generate a large amount of oil gas.In the time that can not meeting the residual needs of the forms such as spontaneous absorption, the hydrocarbon amount generating can not start to discharge hydro carbons.On the contrary, the hydrocarbon source rock that some abundances of organic matter are high or type is good is not in the time entering raw hydrocarbon thresholding, owing to having generated more hydrocarbon amount, once they saturated self need just can start to discharge in a large number hydro carbons.

Raw hydrocarbon thresholding only shows organic transforming degree, does not show the hydrocarbon exhaust condition of hydrocarbon source rock.Do not consider that as hydrocarbon source rock row hydrocarbon critical geologic condition hydrocarbon source rock residual hydrocarbons ability arranges the impact of hydrocarbon critical geologic condition in a large number on hydrocarbon source rock with raw hydrocarbon thresholding.The identical hydrocarbon source rock of raw hydrocarbon amount, have at just a large amount of row's hydrocarbon of mezzanine level, have enter the high stage of ripeness after can not arrange in a large number hydrocarbon.These othernesses are that Regional Geological Conditions causes the residual action of the different sizes of its raw hydrocarbon amount with hydrocarbon source rock self-characteristic.Undercompacted formation hydrocarbon exhaust condition is poor, arranges in a large number compared with normal compacted formation evening hydrocarbon time; Coal seam residual hydrocarbons ability is strong, and row's hydrocarbon contains the hydrocarbon source rock evening of I type organic matter; Mud stone residual hydrocarbons Critical saturation quantity under similarity condition is large compared with carbonatite, therefore arranges evening hydrocarbon time.These explanations, even if raw hydrocarbon thresholding, having considered under the prerequisite of the raw hydrocarbon factor such as abundance of organic matter and type, if do not consider hydrocarbon exhaust condition, can not be arranged as hydrocarbon source rock the critical mark of hydrocarbon in a large number.

Raw hydrocarbon thresholding cannot be explained the one-tenth Tibetan effect of Non-mature Gas And Oil as hydrocarbon source rock row hydrocarbon critical condition.The discovery of prematurity oil reservoir has not only illustrated that raw hydrocarbon thresholding should not discharge critical condition mark in a large number as oil gas, and to becoming late period oily theory also to propose query.Raw hydrocarbon thresholding is only to become late period oil theoretical to be the call for Votes boundary index in the convenient hydrocarbon stage that is divided into proposing, can not to serve as the critical point of an attribute or feature sudden change.Raw hydrocarbon thresholding should not be served as the starting point of organic matter hydrocarbon generation, also unsuitable as the organic catastrophe point that starts a large amount of raw hydrocarbon.

Based on above-mentioned discussion, raw hydrocarbon is not equal to row's hydrocarbon, and the raw hydrocarbon thresholding of hydrocarbon source rock can not characterize hydrocarbon source rock and whether start to arrange hydrocarbon.Hydrocarbon source rock only has and generates and discharged oil gas and just can be called effective hydrocarbon source rock.Therefore, the concept of raw hydrocarbon thresholding can not be evaluated the quality of hydrocarbon source rock objectively, affects the exploration and development of oil gas.

Petroliferous basin hydrocarbon source rock row hydrocarbon characteristic evaluation method has multiple, as kerogen typological method (Pepper A S, Wang Shiqian, Liu Chenggen. a kind of new method of 1995. quantitative evaluation hydrocarbon source rocks rows hydrocarbon characteristics. gas prospecting and exploitation .), physical simulation experiment method (Sweeney J J, Braun R L, Burnham A K, et al. 1995. Chemical kinetic model of hydrocarbon generation, expulsion, and destruction applied to the Maracaibo Basin, Venezuela. AAPG Bulletin, Nakayama K. 1987. Hydrocarbon-expulsion model and its application to Niigata area, Japan. AAPG Bulletin.), maturity of organic matter method (Zhang Wenzheng, Yang Hua, Li Jianfeng, Deng. leading role---Johnson & Johnson row hydrocarbon feature and the Analysis on Mechanism of the long 7 sections of branded oil source rocks of 2006. opinion Ordos Basin in hypotonic Hydrocarbon Formation Reservoirs enrichment. petroleum prospecting and exploitation .), chemical dynemics (Lu Shuanfang, Xu Liheng, Shen Jianian, Deng. 2006. Futai Oilfields become Tibetan phase and the raw matching relationship of arranging the hydrocarbon phase. Xinjiang oil geology .) and basin modelling method (Shi Guangren. 1994. oil gas basin numerical simulation methods. Beijing: petroleum industry publishing house, Burrus J, Wolf S, Osadetz K, et al. 1996. Physical and numerical mod-elling constraints on oil expulsion and accumulation in the Bakken and Lodgepole petroleum systems of the Williston Basin (Canada-USA). Bulletin of Canadian Petroleum Geology.) etc.

These methods are all to set up on the basis of the raw hydrocarbon thresholding of tradition, have ignored the contribution of Component of Premature-imature oil gas etc., have certain drawback.

Summary of the invention

Object of the present invention overcomes the defect that " raw hydrocarbon thresholding " this traditional concept can not objective evaluation hydrocarbon source rock row hydrocarbon potentiality exactly, the concept of hydrocarbon source rock " free hydrocarbon discharge critical condition " has been proposed, start to arrange in a large number the critical geologic condition of hydrocarbon in order to characterize hydrocarbon source rock, think that hydrocarbon source rock is burying in evolutionary process, only have met that self absorption, pore water are dissolved, oil dissolves and the retaining of the various ways such as kapillary shutoff after, just start to discharge in a large number oil gas with free phase, this critical point that starts to discharge in a large number free phase oil gas is called free hydrocarbon and discharges critical condition.

Based on this concept, set up free hydrocarbon in hydrocarbon source rock buried depth evolutionary process and discharged critical condition conceptual model (Fig. 1).

Free hydrocarbon is discharged critical condition three features compared with raw hydrocarbon thresholding: 1. this critical condition is subject to the control of hydrocarbon primary rock producing hydrocarbon effect, residual hydrocarbons effect and the effect of row's hydrocarbon, and the change of arbitrary factor all affects a large amount of discharges of oil gas or the variation of this critical condition; 2. to discharge critical condition be primary rock producing hydrocarbon to free hydrocarbon, stay the turning point of oil gas contradiction effect.Before this, the raw hydrocarbon amount of hydrocarbon source rock is less than residual hydrocarbons Critical saturation quantity; After this, the raw hydrocarbon amount of hydrocarbon source rock is greater than residual hydrocarbons Critical saturation quantity; 3. free hydrocarbon is discharged the critical transition point that critical condition is hydrocarbon source rock row hydrocarbon phase-state change.Before this, hydrocarbon source rock can only be with water-dissolving phase and diffusion phase row hydrocarbon; After this, hydrocarbon source rock, divided by outside water-dissolving phase, diffusion phase row hydrocarbon, is mainly arranged hydrocarbon with free phase in a large number.

The proposition that free hydrocarbon is discharged critical condition concept has not only shown the objectivity that hydrocarbon source rock row hydrocarbon critical geologic condition exists, and has disclosed the mutual relationship of raw hydrocarbon effect, residual hydrocarbons effect and row's hydrocarbon effect and hydrocarbon source rock row hydrocarbon critical geologic condition.The raw hydrocarbon effect of hydrocarbon source rock is abundance of organic matter TOC, type KTI and vitrinite reflectance R _odetermine etc. factor.The residual hydrocarbons ability of hydrocarbon source rock with hydrocarbon source rock under actual geologic condition the suction-operated to oil gas, water-soluble effect, oily molten effect and kapillary plugging action relevant.

Free hydrocarbon is discharged critical condition concept and discrimination standard has been determined the mutual relationship between above-mentioned various geologic agent and geologic function scientifically, quantitatively, thereby is that approach has been opened up in the quantitative examination of arranging hydrocarbon critical geologic condition.Hydrocarbon source rock effectively arrange hydrocarbon start be entered free hydrocarbon discharge critical condition.

The method of discrimination whether hydrocarbon source rock enters free hydrocarbon discharge critical condition is mainly based upon relatively going up of computing hydrocarbon generating quantity of source and hydrocarbon source rock residual hydrocarbons amount magnitude relationship, and fundamental formular is:

Q _p-Q _rm-Q _ew-Q _ed< 0 does not enter free hydrocarbon and discharges critical condition

Q _p-Q _rm-Q _ew-Q _ed=0 discharges critical condition in free hydrocarbon

Q _p-Q _rm-Q _ew-Q _ed> 0 enters free hydrocarbon and discharges critical condition

Wherein, Q _pfor unit volume computing hydrocarbon generating quantity of source, kg/m ³or m ³/ m ³; Q _rmfor unit volume hydrocarbon source rock residual hydrocarbons saturating capacity, kg/m ³or m ³/ m ³; Q _ewfor the water-soluble row's hydrocarbon of unit volume hydrocarbon source rock amount, kg/m ³or m ³/ m ³; Q _edfor unit volume hydrocarbon source rock Diffusive Expulsion For Light Hydrocarbons amount, m ³/ m ³.

By method above, calculate exactly respectively the raw hydrocarbon amount of hydrocarbon source rock in buried depth evolutionary process, residual hydrocarbons Critical saturation quantity and the hydrocarbon amount of discharging with water-dissolving phase and diffusion phase, just can determine geologic condition corresponding when hydro carbons is arranged hydrocarbon in a large number with free phase in hydrocarbon source rock, be also that the free hydrocarbon of hydrocarbon source rock is discharged critical condition.

According to the abundance of organic matter of hydrocarbon source rock, in hydrocarbon source rock density and hydrocarbon source rock, organic oil gas incidence can be calculated the raw hydrocarbon amount of every cubic metre of hydrocarbon source rock, and computing formula is:

Q _p=R _p(i)×ρ _r×TOC

Wherein, Q _pfor every cubic metre of computing hydrocarbon generating quantity of source, kg/m ³or m ³/ m ³; R _pfor the oil gas incidence of organic matrix per ton, kg/t _cor m ³/ t _c; ρ _rfor hydrocarbon source rock density, g/cm ³or t/m ³; TOC is the organic carbon mass percent in hydrocarbon source rock, %; I represents different oil-gas components, dimensionless.

Adsorb on the basis of residual gaseous hydrocarbon amount, water-soluble residual gaseous hydrocarbon amount, the molten residual gaseous hydrocarbon amount of oil and residual liquid hydrocarbon amount calculating respectively hydrocarbon source rock, can calculate hydrocarbon source rock residual hydrocarbons Critical saturation quantity, computing formula is:

Q _rm=Q _rb+Q _rw+Q _rog+Q _ro

Wherein, Q _rmfor unit volume hydrocarbon source rock total residual hydrocarbon amount, kg/m ³or m ³/ m ³; Q _rbfor unit volume hydrocarbon source rock adsorbs residual gaseous hydrocarbon, m ³/ m ³; Q _rwfor the water-soluble residual gaseous hydrocarbon of unit volume hydrocarbon source rock, m ³/ m ³; Q _rogfor the molten residual gaseous hydrocarbon of unit volume hydrocarbon source rock oil, m ³/ m ³; Q _rofor unit volume hydrocarbon source rock residual liquid hydrocarbon, kg/m ³or m ³/ m ³.

According to hydrocarbon source rock water discharge and hydrocarbon, the solubleness in water can be calculated water-dissolving phase row hydrocarbon amount, and computing formula is:

Q _ew=q _w×V _w

Wherein, Q _ewfor unit volume hydrocarbon source rock water-dissolving phase row hydrocarbon amount, kg/m ³or m ³/ m ³; q _wfor hydrocarbon solubleness in water, g/100g water or m ³/ m ³water; V _wfor the water yield that unit volume hydrocarbon source rock is discharged, g, kg or t.

According to the hydrocarbon concentration gradient of the reservoir water of hydrocarbon source rock water and adjacency, history time, hydrocarbon coefficient of diffusion and diffusion area can calculate hydrocarbon source rock diffusion phase row hydrocarbon amount, computing formula is:

$Q_{\mathrm{ed}}={\&Integral;}_0^{t}S\&times;D\frac{\mathrm{dc}}{\mathrm{dz}}\&times;\mathrm{dt}$

Wherein, Q _edfor unit volume diffusion phase row gaseous hydrocarbon amount, kg/m ³or m ³/ m ³; S is in unit volume hydrocarbon source rock, the area of diffusion phase row hydrocarbon, m ²; D is hydrocarbon coefficient of diffusion, cm ²/ s; for hydrocarbon concentration is along the rate of change of dispersal direction, i.e. hydrocarbon concentration gradient, m ³/ m ³m; T is the Diffusive Expulsion For Light Hydrocarbons time, s.

The method can be determined the critical condition of hydrocarbon source rock with the various key components of free phase form discharge, as methane gas is discharged critical condition, heavy hydrocarbon gas discharges critical condition and liquid hydrocarbon is discharged critical condition etc.

Brief description of the drawings

Fig. 1 is that in hydrocarbon source rock buried depth evolutionary process, free hydrocarbon is discharged critical condition conceptual model;

Fig. 2 is the husky three sections of computing hydrocarbon generating quantity of source result of calculation examples of Nan Bao depression;

Fig. 3 is that the Nan Bao husky three sections of hydrocarbon source rock free hydrocarbons discharge of depression critical condition is determined example.

Embodiment

It is based on four parameters that hydrocarbon source rock free hydrocarbon is discharged the definite of critical condition: raw hydrocarbon amount, residual hydrocarbons Critical saturation quantity, water-dissolving phase row's hydrocarbon amount and diffusion phase row hydrocarbon amount, if raw hydrocarbon amount is greater than residual hydrocarbons Critical saturation quantity, water-dissolving phase row's hydrocarbon amount and diffusion phase row hydrocarbon amount three sum, show that hydrocarbon source rock has entered free hydrocarbon and discharged critical condition, otherwise, hydrocarbon source rock not yet enters free hydrocarbon and discharges critical condition, therefore, determine that free hydrocarbon critical condition will calculate respectively the raw hydrocarbon amount of hydrocarbon source rock, residual hydrocarbons Critical saturation quantity, water-dissolving phase row's hydrocarbon amount and diffusion phase row hydrocarbon amount, residual hydrocarbons Critical saturation quantity comprises the residual gaseous hydrocarbon amount of absorption, water-soluble residual gaseous hydrocarbon amount, the molten residual gaseous hydrocarbon amount of oil and residual liquid hydrocarbon amount.

The calculating of raw hydrocarbon amount, computing hydrocarbon generating quantity of source depends on organic carbon mass percent TOC, type KTI and vitrinite reflectance R in hydrocarbon source rock _o, the computing formula of every cubic metre of computing hydrocarbon generating quantity of source is:

Q _p=R _p(i)×ρ _r×TOC

Wherein, Q _pfor every cubic metre of computing hydrocarbon generating quantity of source, kg/m ³or m ³/ m ³; R _pfor the oil gas incidence of organic matrix per ton, kg/t _cor m ³/ t _c; ρ _rfor hydrocarbon source rock density, g/cm ³or t/m ³; TOC is the organic carbon mass percent in hydrocarbon source rock, %; I represents different oil-gas components, dimensionless.

R _pfor the raw hydrocarbon amount of current unit weight organic matter in ground history process, be called for short oil gas incidence, unit weight organic matter represents with organic carbon mass percent. , wherein B is oil gas conversion ratio, can obtain by hydrocarbon source rock thermal simulation experiment.Different oil-gas components, its oil gas incidence difference.

Raw hydrocarbon amount computing formula can unit of account volume hydrocarbon source rock in, the generation quantity of different oil-gas components, this quantity is with buried depth Z and the vitrinite reflectance R of hydrocarbon source rock _ovariation and change, see Fig. 2.

The calculating of residual hydrocarbons Critical saturation quantity, in hydrocarbon source rock, residual hydrocarbons amount comprises liquid residual hydrocarbons amount and gaseous state residual hydrocarbons amount, gaseous state residual hydrocarbons amount comprises the residual gaseous hydrocarbon amount of absorption, water-soluble residual gaseous hydrocarbon amount and the molten residual gaseous hydrocarbon amount of oil.

Residual liquid hydrocarbon amount is calculated, from internal cause, the residual ability of hydrocarbon source rock liquid towards hydrocarbon is mainly subject to the control of four factors, i.e. control, raw hydrocarbon effect control, Temperature-pressure Conditions control and the compaction control to residual liquid hydrocarbon to residual liquid hydrocarbon to residual liquid hydrocarbon of hydrocarbon source rock character to residual liquid hydrocarbon.Its computing formula is:

Q _ro=ρ _o×(φ _n+Δφ)

$S_{\mathrm{om}}=f\left(\mathrm{TOC}\right)\&times;\frac{1}{1-B_k}\&times;e^{-\frac{{\mathrm{\&phi;}}_n}{D}\&CenterDot;{(R_o-R^{\&prime;})}^2}$

f(TOC)=A ₀+A ₁×C+A ₂

B _k=0.81-1.05×R _o+0.18×(R _o) ²

Wherein, Q _rmfor unit volume hydrocarbon source rock residual liquid hydrocarbon amount, kg/m ³; for the factor of porosity of hydrocarbon source rock under normal compaction state, %; for the Residual porosity of hydrocarbon source rock under undercompaction state, %; S _omfor hydrocarbon source rock residual liquid Hydrocarbon saturation, %; F (TOC) is the correlation factor of hydrocarbon source rock residual liquid hydrocarbon amount and abundance of organic matter, dimensionless; B _kfor the weight C of lighter hydrocarbons _1-4account for other composition weight C ₅₊percentage, %; TOC is organic carbon mass percent, %; R _ofor vitrinite reflectance, %; ρ _ofor the density of residual liquid hydrocarbon, kg/m ³; A ₀, A ₁, A ₂, D and R ' be the related coefficient of hydrocarbon source rock absorption liquid hydrocarbon ability and organic carbon mass percent, terrestrial facies shaly source rock can get respectively 0.23,8.81 ,-3.53 ,-1.34 and 0.95.

Adsorptive gaseous hydrocarbon amount is calculated, and character, the reservoir pressure of the main and hydrocarbon source rock of hydrocarbon source rock adsorptive gaseous hydrocarbon amount, buries the factor analysis such as temperature, gaseous hydrocarbon component, gaseous hydrocarbon concentration, and its computing formula is:

$Q_{\mathrm{rb}}=K_i\&times;{\mathrm{\&rho;}}_r\&times;K\left(\mathrm{TOC}\right)\&times;\frac{K\left(R_o\right)}{K_w}\&times;\frac{a_i\&times;b_i\&times;p}{1+b_i\&times;p}\&times;e^{-n\&times;(T-20)}$

$n=\frac{0.02}{0.993+0.0017\&times;p}$

K(R _o)=0.836+0.68×(R _o)+0.498×(R _o) ²

K(TOC)=A ₀+A ₁×TOC

K _w=1+0.445×e ^1-p

$K_i=\left\{\begin{array}{c}0.079\\ 0.00478\\ 0.0066\\ 0.0038\end{array}\right.$ $a_i=\left\{\begin{array}{c}0.117\\ 0.723\\ 1.309\\ 1.833\end{array}\right.$ $b_i=\left\{\begin{array}{c}5.32\\ 0.15\&times;p+0.30\\ 3.04\&times;p+0.6858\\ 8.688\&times;p+1.065\end{array}\right.$ $i=\left\{\begin{array}{c}{\mathrm{CH}}_4\\ C_2{H}_6\\ C_3{H}_8\\ C_4{H}_{10}\end{array}\right.$

Q _rbfor unit volume hydrocarbon source rock adsorptive gaseous hydrocarbon amount, m ³/ m ³; T is formation temperature, DEG C; P is reservoir pressure, Pa; TOC is organic carbon mass percent, %; R _ofor vitrinite reflectance, %; K _wfor hydrocarbon source rock dry moist, dimensionless; ρ _rfor hydrocarbon source rock density, kg/m ³; A ₀, A ₁for the related coefficient of hydrocarbon source rock adsorptive gaseous hydrocarbon ability and organic carbon mass percent, terrestrial facies shaly source rock can be distinguished value 6.43,12.81.

Water-soluble residual gaseous hydrocarbon amount is calculated, mainly the factor of porosity of the solubleness in water and hydrocarbon source rock is relevant to the moisture degree of hydrocarbon source rock, hydro carbons for water-soluble residual gaseous hydrocarbon amount, and the impact of the multiple geologic conditions such as these three factors are under pressure, temperature, salinity, its computing formula is:

Q _rw(i)=q _w(i)×φ×(1-S _o)

Q _rw(i) be in unit volume hydrocarbon source rock, the amount of the water-soluble i component of hole gaseous hydrocarbon, m ³/ m ³; q _w(i) be the amount of the water-soluble i component of the hole gaseous hydrocarbon of unit volume, m ³/ m ³; φ is hydrocarbon source rock factor of porosity, %; S _ofor the oil saturation of hydrocarbon source rock, %; I is for representing CH ₄, C ₂h ₆, C ₃h ₈deng gaseous hydrocarbon component.

$q_w\left(i\right)=q_w(1,T,p,X_K)\&times;\frac{q_w(i,T,p)}{q_w(1,T,p)}$

q _w(1,T,P,X _k)=(8.05×T ^1.33)×(0.994-0.0032×X _k+0.0007×T)

q _w(1,T,P)=a _0i+a _1i×P+a _2i×T+a _3i×P ²+a _4i×T ²+a _5i×P×T

$\left\{\begin{array}{c}{a}_{01}=2.416\\ a_{11}=0.00961\\ a_{21}=-0.0348\\ a_{31}=-1.04\&times;{10}^{-5}\\ a_{41}=9.05\&times;{10}^{-7}\\ a_{51}=6.14\&times;{10}^{-5}\end{array}\right.$ $\left\{\begin{array}{c}{a}_{02}=1.229\\ a_{12}=0.00137\\ a_{22}=-0.0175\\ a_{32}=-3.871\&times;{10}^{-6}\\ a_{42}=3.94\&times;{10}^{-7}\\ a_{52}=3.27\&times;{10}^{-5}\end{array}\right.$ $\left\{\begin{array}{c}{a}_{03}=0.231\\ a_{13}=0\\ a_{23}=0\\ a_{33}=-3.31\&times;{10}^{-6}\\ a_{43}=4.26\&times;{10}^{-7}\\ a_{53}=1.141\&times;{10}^{-5}\end{array}\right.$

Wherein, q _w(i) be the water-soluble gaseous hydrocarbon amount of unit volume hole, m ³/ m ³; T is local water temperature, DEG C; P is reservoir pressure, Pa; X _k-reservoir water salinity, g/l; q _w(1, T, P, X _k) for being stressed, the methane gas of temperature and the water salinity control solubleness in water, dimensionless; q _w(i, T, P) is the running parameter of gaseous hydrocarbon solubility with pressure, temperature and water salinity, dimensionless; I is for representing CH ₄, C ₂h ₆, C ₃h ₈deng gaseous hydrocarbon component.

The molten residual gaseous hydrocarbon amount of oil is calculated, the molten gaseous hydrocarbon amount of oil is mainly relevant to oil saturation and the solubleness of gaseous hydrocarbon in oil of the factor of porosity of hydrocarbon source rock, pore water, and the impact of the multiple geologic conditions such as these three factors are under pressure, temperature, salinity, its computing formula is:

Q _rog(i)=q _o(i)×φ×S _o

q _o(i)=4.95×K(i)×K(ρ _o)

K(i)=(A _i+B _i×P)/100

K(ρ _o)=1.75-1.8×ρ _o

q _og(T,P)=D ₀+D ₁×P+D ₂×T

$\left\{\begin{array}{c}{A}_1=62.63\\ A_2=18.68\\ A_3=9.89\\ A_4=4.203\end{array}\right.$ $\left\{\begin{array}{c}{B}_1=0.00716\\ B_2=0.00365\\ B_3=0.00212\\ B_4=0.00085\end{array}\right.$ $\left\{\begin{array}{c}{D}_0=-0.726\\ D_1=0.387\\ D_2=-0.0323\end{array}\right.$

Q _rog(i) be that unit volume hydrocarbon source rock is with the residual i component gaseous hydrocarbon amount of the molten form of oil, m ³/ m ³; q _o(i) the i component gaseous hydrocarbon amount of dissolving for unit volume liquid hydrocarbon, m ³/ m ³; for hydrocarbon source rock factor of porosity, %; S _ofor the oil saturation of hydrocarbon source rock, %; q _othe i component gaseous hydrocarbon amount that (T, P) dissolves for unit volume liquid hydrocarbon, m ³/ m ³; K (i) is the ratio that different gaseous hydrocarbon components account for oily molten gaseous hydrocarbon amount, dimensionless; K (ρ _o) be the changed factor of oily molten gaseous hydrocarbon amount with oil density, dimensionless; ρ _ofor the density of liquid hydrocarbon, kg/m ³; q _og(T, P) is the function that is subject to the molten gaseous hydrocarbon amount of oil of Temperature-pressure Conditions control; T is formation temperature, DEG C; P is reservoir pressure, pa; I is for representing CH ₄, C ₂h ₆, C ₃h ₈deng gaseous hydrocarbon component.

The calculating of water-dissolving phase row hydrocarbon amount, the hydro carbons of discharging with water-soluble phase is mainly gaseous hydrocarbon.Gas flow that water-soluble phase is discharged is main, and the geology key element such as water discharge of the solubleness in water, hydrocarbon source rock is relevant to gaseous hydrocarbon, and its computing formula is:

$Q_{\mathrm{ew}}=(Q_o+Q_{\mathrm{cw}})\underset{1}{\overset{4}{\mathrm{\&Sigma;}}}{q}_w\left(i\right)$

Wherein, Q _ewfor the gas flow that unit volume hydrocarbon source rock is discharged with water-soluble phase, m ³/ m ³; q _w(i) be the pore water of unit volume, the i component gaseous hydrocarbon amount of dissolving, m ³/ m ³; Q _ofor the hydrocarbon source rock of unit volume, the Fluid Volume that discharged by compaction, m ³; Q _cwfor the hydrocarbon source rock of unit volume, the dehydrating amount of its smectite, m ³.

$Q_o=\frac{{\mathrm{\&phi;}}_o-\mathrm{\&phi;}}{1-\mathrm{\&phi;}}\&times;(1-S_o)$

Q _ofor the hydrocarbon source rock of unit volume, the Fluid Volume of discharging under compaction, m ³; Φ is the actual measurement factor of porosity of hydrocarbon source rock, %; Φ ₀factor of porosity while being positioned at earth's surface Conditions of Buried Depth for hydrocarbon source rock, %; S _ofor the oil saturation of hydrocarbon source rock, %.

The computing formula of Clay Mineral Transformation dehydrating amount is:

Q _cw=0.245×C _clay×I _m×ρ _r(Z)

$I_m=\frac{1}{\mathrm{\&pi;}}\&times;\mathrm{MMI}\&times;\{\frac{\mathrm{\&pi;}}{2}+\mathrm{arctg}[K\&times;(Z_t-Z_m)\left]\right\}$

$K=\mathrm{tg}(\mathrm{\&pi;}\&times;\frac{I_t}{\mathrm{MMI}}-\frac{\mathrm{\&pi;}}{2})\&times;\frac{1}{Z_t-Z_m}$

Wherein, Q _cwfor the hydrocarbon source rock of unit volume, its smectite transforms the water yield of deviating from, m ³; I _mfor smectite changes into illitic amount, %; K is smectite conversion rate coefficient, dimensionless; MMI is in hydrocarbon source rock, the initial content of smectite, %; C _clayfor the content of hydrocarbon source rock CLAY MINERALS AND THEIR SIGNIFICANCE, %; I _tfor illitic content in hydrocarbon source rock, %; Z _tfor the buried depth of hydrocarbon source rock, m; Z _mfor smectite is at dehydration corresponding buried depth when peak, m; ρ _r(Z) in the time that buried depth is Z, the density of hydrocarbon source rock, kg/m ³.

The calculating of diffusion phase row hydrocarbon amount is mainly gaseous hydrocarbon with the hydro carbons that spreads phase discharge.The diffusion phase exhaust scale of construction is mainly relevant to the geology key element such as coefficient of diffusion, the diffusion time of gaseous hydrocarbon of the thickness of hydrocarbon source rock, gaseous hydrocarbon, and computing formula is:

$Q_{\mathrm{ed}}={\&Integral;}_0^{t}S\&times;D\frac{\mathrm{dc}}{\mathrm{dz}}\&times;\mathrm{dt}$

Wherein, Q _edfor unit volume diffusion phase row gaseous hydrocarbon amount, kg/m ³or m ³/ m ³; S is in unit volume hydrocarbon source rock, the area of diffusion phase row hydrocarbon, m ²; D is hydrocarbon coefficient of diffusion, cm ²/ s; for hydrocarbon concentration is along the rate of change of dispersal direction, i.e. hydrocarbon concentration gradient, m ³/ m ³m; T is the Diffusive Expulsion For Light Hydrocarbons time, s.

It should be added that, when the method is discharged critical condition at definite gaseous hydrocarbon, for gaseous hydrocarbon, its discharge rate also comprises the molten gaseous hydrocarbon amount of arranging mutually of oil.Gas flow that the molten phase of oil is discharged is main, and the geology key element such as discharge oil mass of the solubleness in oil, hydrocarbon source rock is relevant to gaseous hydrocarbon, and its computing formula is:

$Q_{\mathrm{eo}}=(Q_r-Q_{\mathrm{ro}})\&times;\underset{1}{\overset{4}{\mathrm{\&Sigma;}}}{q}_o\left(i\right)$

In formula: Q _eothe hydrocarbon source rock of-unit volume, the gas flow of discharging with the molten phase of oil, m ³/ m ³; Q _rthe oil mass that-unit volume hydrocarbon source rock generates, m ³/ m ³; Q _rothe oil mass that-unit volume hydrocarbon source rock is remaining, m ³/ m ³; q _o(i)-the solubleness of dissimilar gaseous hydrocarbon in oil, m ³/ m ³; I is for representing CH ₄, C ₂h ₆, C ₃h ₈deng gaseous hydrocarbon component.

Free phase row hydrocarbon amount is calculated, and after raw hydrocarbon amount deducts residual hydrocarbons saturating capacity, water-dissolving phase row's hydrocarbon amount and diffusion phase row hydrocarbon amount, residue is free phase row hydrocarbon amount, and its computing formula is:

Q _es=Q _p-(Q _rm+Q _ew+Q _ed)

Wherein, Q _pfor unit volume computing hydrocarbon generating quantity of source, kg/m ³or m ³/ m ³; Q _rmfor the maximum residual hydrocarbons amount of unit volume hydrocarbon source rock, kg/m ³or m ³/ m ³; Q _ewfor unit volume hydrocarbon source rock water-dissolving phase row hydrocarbon amount, kg/m ³or m ³/ m ³; Q _edfor unit volume hydrocarbon source rock diffusion phase row gaseous hydrocarbon amount, m ³/ m ³; Q _esfor unit volume hydrocarbon source rock free phase row hydrocarbon amount, kg/m ³or m ³/ m ³.

Work as Q _eswhen <0, hydrocarbon source rock does not reach free hydrocarbon and discharges critical condition; Work as Q _es=0 o'clock, hydrocarbon source rock was in free hydrocarbon and discharges critical condition, the buried depth Z that now hydrocarbon source rock is corresponding or vitrinite reflectance R _oall can be used to characterize the critical condition that hydrocarbon source rock free hydrocarbon is discharged, in petroliferous basin, buried depth Z and vitrinite reflectance R _oconventionally there is good correlativity; Work as Q _eswhen >0, hydrocarbon source rock has entered free hydrocarbon and has discharged critical condition.

For total hydrocarbon, free phase row hydrocarbon amount is calculated as the above; For gaseous hydrocarbon, the amount of coalbed methane generated that is calculated as of free phase air capacity deducts residue gas saturating capacity, water-dissolving phase air capacity, oily molten phase air capacity and diffusion phase air capacity sum; For liquid hydrocarbon, the calculating of free phase oil drain quantity, for oil generating quantity deducts oil residues saturating capacity.

This method can be determined the critical condition of hydrocarbon source rock with the various key components of free phase form discharge, as methane gas is discharged critical condition, heavy hydrocarbon gas discharges critical condition and liquid hydrocarbon is discharged critical condition etc., sees Fig. 3.

In practical application, this method has realized primary rock producing hydrocarbon, has stayed, arranged the quantitative calculating of hydrocarbon amount, free hydrocarbon is discharged to definite principle that meets material balance of critical geologic condition, has very important Practical significance.

Claims (6)

1. definite hydrocarbon source rock free hydrocarbon is discharged a method for critical condition, said method comprising the steps of:

(1) obtain organic oil gas incidence and hydrocarbon source rock density in the abundance of organic matter, hydrocarbon source rock of hydrocarbon source rock by hydrocarbon source rock Pyrolysis Experiment and rock density test experiments, and then calculate the raw hydrocarbon amount of every cubic metre of hydrocarbon source rock;

(2) adsorb on the basis of residual gaseous hydrocarbon amount, water-soluble residual gaseous hydrocarbon amount, the molten residual gaseous hydrocarbon amount of oil and residual liquid hydrocarbon amount calculating respectively every cubic metre of hydrocarbon source rock, calculate every cubic metre of hydrocarbon source rock residual hydrocarbons Critical saturation quantity;

(3) every cubic metre of hydrocarbon source rock water-dissolving phase row hydrocarbon amount of the Calculation of Solubility in water according to every cubic metre of hydrocarbon source rock water discharge and hydrocarbon;

(4) according to the gaseous hydrocarbon concentration gradient of every cubic metre of hydrocarbon source rock water and the reservoir water of adjacency, history time, hydrocarbon coefficient of diffusion, diffusion area calculate every cubic metre of hydrocarbon source rock diffusion phase and arrange gaseous hydrocarbon amount;

(5) determine hydrocarbon source rock free hydrocarbon discharge critical condition, the magnitude relationship of more every cubic metre of computing hydrocarbon generating quantity of source and residual hydrocarbons Critical saturation quantity, water-dissolving phase row gaseous hydrocarbon amount, diffusion phase row gaseous hydrocarbon amount three sum, in the time that raw hydrocarbon amount is less than three's sum, hydrocarbon source rock does not reach free hydrocarbon and discharges critical condition; In the time that every cubic metre of raw hydrocarbon amount equals three's sum, hydrocarbon source rock reaches free hydrocarbon and discharges critical condition, now, and the buried depth Z that hydrocarbon source rock is corresponding and vitrinite reflectance R _oall can characterize the critical condition that hydrocarbon source rock free hydrocarbon is discharged.

2. according to the method described in right 1, wherein, step (1) comprises the calculating to every cubic metre of computing hydrocarbon generating quantity of source, and computing formula is:

Q _p=R _p(R _o,KTI)×ρ _r(Z)×TOC

Wherein, Q _pfor the raw hydrocarbon amount of unit volume hydrocarbon source rock, kg/m ³or m ³/ m ³; R _pfor the oil gas incidence of organic matter per ton, kg/t _cor m ³/ t _c; ρ _rfor hydrocarbon source rock density, g/cm ³or t/m ³; TOC is the organic carbon percentage composition in hydrocarbon source rock, %; R _ofor vitrinite reflectance, %; KTI is that cheese is followed index of type, dimensionless; Z is hydrocarbon source rock buried depth, m.

3. according to the method described in right 1, wherein, step (2) comprises the calculating to every cubic metre of hydrocarbon source rock residual hydrocarbons Critical saturation quantity, and computing formula is:

Q _rm=Q _rb+Q _rw+Q _rog+Q _ro

Wherein, Q _rmfor unit volume hydrocarbon source rock residual hydrocarbons Critical saturation quantity, kg/m ³or m ³/ m ³; Q _rbfor unit volume hydrocarbon source rock adsorbs residual gaseous hydrocarbon, m ³/ m ³; Q _rwfor the water-soluble residual gaseous hydrocarbon of unit volume hydrocarbon source rock, m ³/ m ³; Q _rogfor the molten residual gaseous hydrocarbon of unit volume hydrocarbon source rock oil, m ³/ m ³; Q _rofor unit volume hydrocarbon source rock residual liquid hydrocarbon, kg/m ³or m ³/ m ³.

4. according to the method described in right 1, wherein, step (3) comprises the calculating to every cubic metre of hydrocarbon source rock water-dissolving phase row hydrocarbon amount, and computing formula is:

Q _ew=q _w×V _w

Wherein, Q _ewfor unit volume hydrocarbon source rock water-dissolving phase row hydrocarbon amount, kg/m ³or m ³/ m ³; q _wfor hydrocarbon solubleness in water, g/100g water or cm ³/ 100cm ³water; V _wfor the water yield that unit volume hydrocarbon source rock is discharged, g, kg or t.

5. according to the method described in right 1, wherein, step (4) comprises the calculating to every cubic metre of hydrocarbon source rock diffusion phase row gaseous hydrocarbon amount, and computing formula is:

$Q_{\mathrm{ed}}={\&Integral;}_0^{t}S\&times;D\frac{\mathrm{dc}}{\mathrm{dz}}\&times;\mathrm{dt}$

Wherein, Q _edfor unit volume diffusion phase row gaseous hydrocarbon amount, kg/m ³or m ³/ m ³; S is in unit volume hydrocarbon source rock, the area of diffusion phase row hydrocarbon, m ²; D is hydrocarbon coefficient of diffusion, cm ²/ s; for hydrocarbon concentration is along the rate of change of dispersal direction, i.e. hydrocarbon concentration gradient, m ³/ m ³m; T is the Diffusive Expulsion For Light Hydrocarbons time, s.

6. according to the method described in right 1, wherein, step (5) comprises determines hydrocarbon source rock free hydrocarbon discharge critical condition, and computing formula is:

Q _es=Q _p(Q _rm+Q _ew+Q _ed)

Wherein, Q _pfor unit volume computing hydrocarbon generating quantity of source, kg/m ³or m ³/ m ³; Q _rmfor unit volume hydrocarbon source rock residual hydrocarbons Critical saturation quantity, kg/m ³or m ³/ m ³; Q _ewfor unit volume hydrocarbon source rock water-dissolving phase row hydrocarbon amount, kg/m ³or m ³/ m ³; Q _edfor unit volume hydrocarbon source rock diffusion phase row gaseous hydrocarbon amount, m ³/ m ³; Q _esfor unit volume hydrocarbon source rock free phase row hydrocarbon amount, kg/m ³or m ³/ m ³;

Work as Q _eswhen <0, hydrocarbon source rock does not reach free hydrocarbon and discharges critical condition; Work as Q _es=0 o'clock, hydrocarbon source rock was in free hydrocarbon and discharges critical condition, the buried depth Z that now hydrocarbon source rock is corresponding or evolution degree R _oall can be used to characterize the critical condition that hydrocarbon source rock free hydrocarbon is discharged.