CN104181092A - Method for quantitatively expressing carbonate rock pore evolution contribution - Google Patents

Abstract

The invention discloses a method for quantitatively expressing the carbonate rock pore evolution contribution, comprising the following steps: firstly, predicting the original porosity; secondly, solving the porosity lost by cementation; thirdly, solving the porosity lost by intergranular pressure solution; fourthly, solving the porosity lost by mechanical compaction; and fifthly, repeating steps 1-4, and calculating the contribution value of the carbonate rock mechanical compaction, the intergranular pressure solution and the cementation at different positions to reduction of the porosity. Compared with the prior art, the method has the advantage of providing a new thought for the aspects of pore evolution of the carbonate rock, the volume of the carbonate rock corroded by intergranular pressure solution and the number of cements provided for flow of the carbonate rock dissolved to underground fluid, so as to seek for high-porosity areas from pore evolution contribution and explore a high quality reserve stratum in the carbonate rock.

Description

A kind of method of quantitatively characterizing evolution of carbonate rock's pore contribution

Technical field

The present invention relates to the method for Compaction, particle pressolution and the cementation relative scale to factor of porosity reduction, relate in particular to a kind of method of quantitatively characterizing evolution of carbonate rock's pore contribution.

Background technology

The pore evolution of sandstone is generally taken as the leading factor by Compaction, then adds a certain amount of cementation.By contrast, the pore evolution of carbonatite develops and wants complicated a lot of compared with sandstone pores, affect hole effect except above-mentioned two kinds, particle pressolution has occupied indispensable status on evolution of carbonate rock's pore, and multifactor impact the quantitatively characterizing that evolution of carbonate rock's pore causes the contribution of its pore evolution and just become difficulty relatively.

Carbonate porosity degree successively decreases with degree of depth exponentially.The reduction of factor of porosity is Compaction, intergranular pressolution (IPS) and the coefficient result of cementation.Compaction refers to the increase due to burden pressure, and skeleton particle rearranges and the volume of voids that causes reduces; Intergranular pressolution refers between pressure inducement contact particle corrosion occurs, the volume of voids minimizing causing; Hypothesis and controlling factor forefathers that pressolution exists have done excessive quantity research (Weyl, 1959; Tada and Siever, 1986; Houseknecht and Hathon, 1987; Moore, 1989; Bathurst, 1995; , 1996), no longer describe in detail herein.Cementation refers to the precipitating action that mineral occur in pore space.

What attempt the earliest quantitative examination limestone porosity evolution process is Coogan (1970), the compaction that application pack density and filling index are measured carbonatite, although the compaction that application pack density and filling index have been measured carbonatite, does not distinguish the relative intensity that Compaction, intergranular pressolution and cementation act on respectively.

Rittenhouse (1971) improves research method, and Manus and Coogan (1974) have calculated because particle causes volume to reduce the factor of porosity causing by square and rhomboid filling arrangement and reduced.

It is a kind of to the most comprehensively computing method of coarse particle carbonatite compacting that Coogan and Manus (1975) provides, and three kinds of factors controlling factor of porosity are tested out: (1) dynamic factor (overlying formation pressure, temperature, the duration of fossil pressure, pore-fluid pressure and pore fluid); (2) internal factor (grain size, particle shape, the sorting of particle, the filling of particle and mineralogical composition); (3) damper (burying front cementing).

Vinopal and Coogan (1978) have calculated the volume of the limestone of difformity particle composition.

Meyers and Hill (nineteen eighty-three) have studied the porosity evolution process on New Mexico lake valley stratum, think that the loss of 38% original porosity is subject to compaction control, remaining are subject to cementation control.

Moore (1989) by public data and the theoretic sample labor of Rittenhouse (1971) Compaction, intergranular pressolution and cementation role in factor of porosity reduction process.

The research that the division of Gregg etc. (1993) by the diagenetic stage is quantitative the dolomitic porosity evolution in Bonneterre area.

Although forefathers have carried out a large amount of research, the quantitatively characterizing that Compaction, intergranular pressolution and cementation are reduced at carbonate porosity degree is the blank in research also.

Summary of the invention

The present invention is in order to solve above-mentioned deficiency, and a kind of method of quantitatively characterizing evolution of carbonate rock's pore contribution is provided.

Above-mentioned purpose of the present invention realizes by following technical scheme: a kind of method of quantitatively characterizing evolution of carbonate rock's pore contribution,

The first, prediction original porosity;

The second, ask for the factor of porosity that cementation is lost;

The 3rd, ask for the factor of porosity that intergranular pressolution loses;

The 4th, ask for the factor of porosity that Compaction loses;

The 5th, repeating step 1～4, the amount that carbonatite Compaction, intergranular particle pressolution and the cementation at calculating diverse location place reduces factor of porosity.

Total losses amount (the PL of hole _tOT) be Compaction loss amount (PL _mC), intergranular pressolution loss amount (PL _iPS) and cementation loss amount (PL _cEM) sum.

PL _TOT＝PL _MC+PL _IPS+PL _CEM (1)

Total porosity (the PL of loss _tOT) should equal original porosity (PO) with residual porosity sum:

PO＝PL _MC+PL _IPS+PL _CEM+P _LO (2)

Wherein, P _lOresidue interparticle porosity.

Specifically comprise the following steps:

Step 1: prediction original porosity (PO)

In order quantitatively to calculate PL _mC, PL _iPSand PL _cEM, need to estimate an original porosity value; The good spheric grain of sorting is respectively 47%, 40%, 40%, 29%, 26% and 26% with the original porosity of square, the oblique square of I type, the oblique square of II type, square, I type triangular form, the filling of II type triangular form mode, and its original porosity of the spheric grain of random alignment is about 40%;

Step 2: the factor of porosity (PL that asks for cementation loss _cEM)

Factor of porosity loss (the PL that cementation causes _cEM) a calculating utilization note point method measure, and it equals the percentage of grain-to-grain cementation thing; Specific practice is, under thin slice, find at random and observe 3-5 the visual field, drive thin slice rotation by rotatable stage, printing opacity has the cementing matter that is of significant change, record respectively each area S1～Sn of cementing matter within sweep of the eye, wherein S1～Sn represents respectively 1～n the area of cementing matter within sweep of the eye, records the area S in FOV (Field of View); That is:

${\mathrm{PL}}_{\mathrm{CEM}}=\frac{S1+S2+....+\mathrm{Sn}}{n\·S}---\left(3\right)$

Step 3: the factor of porosity (PL that asks for the loss of intergranular pressolution _iPS)

Mitra and Beard (1980) have proposed the method for quantitative calculating intergranular pressolution loss factor of porosity (PLIPS); Mitra and Beard be the intergranular pressolution owing to spheric grain by the loss factor of porosity calculating in theory;

V _IPS＝nπh ²(3r-h)/3 (4)

V _iPSfor the volume on pressure solution ball top, n is the number (be generally 2, the top of spheroid and bottom are divided) on ball top, and h is corrosion height, and r is the original radius of spheric grain;

The original radius r of corrosion height h and particle is determined according to the particle size of the petrographic thin section microphoto of choosing, specific practice is: select continuously at random n oolith that lives through vertical compression, taking the maximum radius of each oolith as original radius r, utilize compasses to draw to each oolith the prototype structure that circle has been rebuild oolith, measure the original radius r of particle of each oolith, the least radius of each oolith is intergranular pressolution remaining particle radius rh afterwards, i.e. corrosion amount h=r-rh;

For the oolith of i vertical compression, i=1,2 ... n;

Factor of porosity P1 before corrosion _ican be expressed as

P1 _i＝[(2r) ³-4/3πr ³]/(2r) ³ (5)

Factor of porosity P2 after corrosion _ican be expressed as:

P2 _i＝[(2r) ²*(2*rh)-(4/3πr ³-V _IPS)]/[(2r) ²*(2*rh)] (6)

Factor of porosity (the PL of the oolith pressolution loss of i vertical compression _iPSi) be:

PL _IPSi＝P1 _i-P2 _i (7)

${\mathrm{PL}}_{\mathrm{IPS}}=\frac{\underset{i=1}{\overset{i=n}{\mathrm{\Σ}}}{\mathrm{PL}}_{\mathrm{IPSi}}}{n}---\left(8\right)$

Step 4: the factor of porosity (PL that asks for Compaction loss _mC)

Granular limestone factor of porosity is P now _lO(by core porosity measuring), the factor of porosity (PL of mechanical ramming loss _mC) can utilize the distortion of formula 2 to calculate, suppose that original porosity is 40%;

PL _MC＝0.4-P _LO-(PL _IPS+PL _CEM) (9)

Step 5: repeating step 1～4, the amount that carbonatite Compaction, intergranular particle pressolution and the cementation at calculating diverse location place reduces factor of porosity.

The above-mentioned quantitatively characterizing of determining Compaction, intergranular pressolution and cementation in carbonatite of discussing.

The present invention's advantage is compared with prior art: the pore evolution that method of the present invention is carbonatite, the aspects such as the cementing matter quantity that the carbonatite volume of intergranular pressolution corrosion and dissolution of carbonate rock provide for underground fluid flows provide new thinking, be intended to find high hole district from pore evolution contribution, seek the High-quality Reservoir in carbonatite.

Brief description of the drawings

Fig. 1 is a kind of process flow diagram of method of quantitatively characterizing evolution of carbonate rock's pore.

Fig. 2 is general phosgene field, Sichuan P6Jing Changxing group limestone sample particle type and intergranular pressure solution contact relation figure.Wherein (A) sample (5350.4m) is inserted cementing; (B) sample (5307m) by spheric grain, micrite and bituminization before calcareous cement form; (C) sample (5281m) by micrite and bituminization after calcareous cement form; (D) sample (5251m) by spheric grain, a large amount of sphere marine facies cementing matter and bituminization before calcareous cement form.

Fig. 3 is the model of the factor of porosity of intergranular pressolution loss.

The vertical reduction measuring method of Fig. 4 Sichuan general phosgene field P6Jing Changxing group limestone sample (5350.4m) carbonate formation schematic diagram; (A) being photo under the mirror of 20 sample label ooliths, is (B) oolith original boundaries in estimation (A).

Fig. 5 is mechanical ramming, intergranular pressolution and cementation factor of porosity loss amount accumulative histogram.

Embodiment

Below in conjunction with embodiment, the present invention is described in further detail:

P6Jing Changxing, general gloss oil field, river the Northeast group limestone is the ideal area of quantitative examination Compaction, intergranular pressolution and cementation, reason have following some: they are made up of (1) spherical particle, make to rebuild the border of primary granule and the particle volume of counting loss is achieved; (2) emerging group of this head of district lacks the influential siliceous petroclastic rock particle of compaction tool and clay mineral; (3) this stratum has experienced relatively simple porosity evolution, crack agensis, and P6 well (5350.4m) factor of porosity is 2.3% (Fig. 2).

Although some particle is crystallite, the skin of most of particles all shows radial concentric structure.For all grain types, its prototype structure has all obtained preservation.Spherical structure and original kalzit mineral composition make mineralogical composition and particle shape drop to minimum on the impact of porosity evolution.

Concrete implementation step is:

Step 1: the prediction (PO) of original porosity

The good spheric grain of local area sorting is respectively 47%, 40%, 40%, 29%, 26% and 26% with the original porosity of square, the oblique square of I type, the oblique square of II type, square, I type triangular form, the filling of II type triangular form mode.The original porosity identical best (40%) of the carbonatite that the original porosity under oblique side's filling method and separation condition are good, lower original porosity too low (being respectively 30% and 25%) is arranged in square and triangular form filling, therefore select oblique square, original porosity is 40%.

Step 2: the factor of porosity (PL of cementation loss _cEM)

Factor of porosity loss (the PL that cementation causes _cEM) utilize note point method to measure, it equals the percentage of grain-to-grain cementation thing.Specific practice is, under thin slice, find at random and observe 5 visuals field, drive thin slice rotation by rotatable stage, printing opacity has the cementing matter that is of significant change, record respectively each area S1～S5 of cementing matter within sweep of the eye, wherein S1～S5 represents respectively 1～5 area of cementing matter within sweep of the eye, records the area S in FOV (Field of View).

${\mathrm{PL}}_{\mathrm{CEM}}=\frac{S1+S2+....+\mathrm{Sn}}{n\·S}=\frac{12.66+13.75+10.77+11.62+11.24}{5\×100}\×100\%=12\%---\left(10\right)$

Step 3: the factor of porosity (PL of intergranular pressolution loss _cEM)

According to particle size, in same position, P6 well (5350.4m) is selected 20 points of microphoto of the oolith that lives through vertical compression.Utilize compasses to draw to each oolith the prototype structure that circle has been rebuild oolith; taking the maximum radius of each oolith as original radius r; utilize compasses to draw to each oolith the prototype structure that circle has been rebuild oolith; measure the original radius r of particle of each oolith; the least radius of each oolith is intergranular pressolution remaining particle radius rh afterwards, i.e. corrosion amount h=r-rh.

New particle volume equals primary granule volume and deducts the volume (V that corrosion ball pushes up _cEM)

To scheme in (4) No. 1 point as example, its r=1.39cm, rh=0.88cm, i.e. h=r-rh=0.51cm, the factor of porosity P1 before corrosion ₁can be expressed as

P1 ₁＝[(2r) ³-4/3πr ³]/(2r) ³＝47.6％ (11)

Factor of porosity P2 after corrosion ₁can be expressed as

P2 ₁＝{(2r) ²(2×rh)-[4/3πr ³-n/3πh ²(3r-h)]}/(2r) ²(2×rh)＝31.95％ (12)

Factor of porosity (the PL of pressolution loss _iPS1) be:

PL _IPS1＝P1 ₁-P2 ₁＝15.69％ (13)

These 20 sampling points are asked in PL _iPSiscope be 9.4%-24.1%, PL _iPSirepresent the factor of porosity of the pressolution loss of i sampling point, the factor of porosity (PL of whole well depth point pressolution loss _iPS) be:

${\mathrm{PL}}_{\mathrm{IPS}}=\frac{\underset{i=1}{\overset{i=20}{\mathrm{\Σ}}}{\mathrm{PL}}_{\mathrm{IPSi}}}{20}=14.7\%---\left(14\right)$

Step 4: the factor of porosity (PL of Compaction loss _mC)

Due to P6 well (5350.4m) now granular limestone factor of porosity be 2.3%, the factor of porosity (PL of mechanical ramming loss _mC) can utilize the distortion of formula 2 to calculate, suppose that original porosity is 40%:

PL _MC＝0.4-P _LO-(PL _IPS+PL _CEM) (15)

Result shows the factor of porosity (PL of mechanical ramming loss _mC) loss average pore be 13.6%.

Step 5: repeating step 1～3, the relative scale that carbonatite Compaction, intergranular particle pressolution and the cementation at calculating diverse location place reduces factor of porosity, is shown in Fig. 4.

The foregoing is only embodiments of the invention; not thereby limit the scope of the claims of the present invention; every equivalent structure or conversion of equivalent flow process that utilizes instructions of the present invention to do, or be directly or indirectly used in other relevant technical fields, be all in like manner included in scope of patent protection of the present invention.

Claims (1)

1. a method for quantitatively characterizing evolution of carbonate rock's pore contribution, is characterized in that: comprise the following steps:

Step 1: prediction original porosity (PO)

In order quantitatively to calculate PL _mC, PL _iPSand PL _cEM, need to estimate an original porosity value; The good spheric grain of sorting is respectively 47%, 40%, 40%, 29%, 26% and 26% with the original porosity of square, the oblique square of I type, the oblique square of II type, square, I type triangular form, the filling of II type triangular form mode, and its original porosity of the spheric grain of random alignment is about 40%;

Step 2: the factor of porosity (PL that asks for cementation loss _cEM)

Factor of porosity loss (the PL that cementation causes _cEM) a calculating utilization note point method measure, and it equals the percentage of grain-to-grain cementation thing; Specific practice is, under thin slice, find at random and observe 3-5 the visual field, drive thin slice rotation by rotatable stage, printing opacity has the cementing matter that is of significant change, record respectively each area S1～Sn of cementing matter within sweep of the eye, wherein S1～Sn represents respectively 1～n the area of cementing matter within sweep of the eye, records the area S in FOV (Field of View); That is:

${\mathrm{PL}}_{\mathrm{CEM}}=\frac{S1+S2+....+\mathrm{Sn}}{n\·S}---\left(3\right)$

Step 3: the factor of porosity (PL that asks for the loss of intergranular pressolution _iPS)

Mitra and Beard (1980) have proposed the method for quantitative calculating intergranular pressolution loss factor of porosity (PLIPS); Mitra and Beard be the intergranular pressolution owing to spheric grain by the loss factor of porosity calculating in theory;

V _IPS＝nπh ²(3r-h)/3 (4)

V _iPSfor the volume on pressure solution ball top, n is the number (be generally 2, the top of spheroid and bottom are divided) on ball top, and h is corrosion height, and r is the original radius of spheric grain;

The original radius r of corrosion height h and particle is determined according to the particle size of the petrographic thin section microphoto of choosing, specific practice is: select continuously at random n oolith that lives through vertical compression, taking the maximum radius of each oolith as original radius r, utilize compasses to draw to each oolith the prototype structure that circle has been rebuild oolith, measure the original radius r of each oolith particle, the least radius of each oolith is intergranular pressolution remaining particle radius rh afterwards, i.e. corrosion amount h=r-rh;

For the oolith of i vertical compression, i=1,2 ... n;

Factor of porosity P1 before corrosion _ican be expressed as

P1 _i＝[(2r) ³-4/3πr ³]/(2r) ³ (5)

Factor of porosity P2 after corrosion _ican be expressed as:

P2 _i＝[(2r) ²*(2*rh)-(4/3πr ³-V _IPS)]/[(2r) ²*(2*rh)] (6)

Factor of porosity (the PL of the oolith pressolution loss of i vertical compression _iPSi) be:

PL _IPSi＝P1 _i-P2 _i (7)

${\mathrm{PL}}_{\mathrm{IPS}}=\frac{\underset{i=1}{\overset{i=n}{\mathrm{\Σ}}}{\mathrm{PL}}_{\mathrm{IPSi}}}{n}---\left(8\right)$

Step 4: the factor of porosity (PL that asks for Compaction loss _mC)

Granular limestone factor of porosity is P now _lO(by core porosity measuring), the factor of porosity (PL of mechanical ramming loss _mC) can utilize the distortion of formula 2 to calculate, suppose that original porosity is 40%;

PL _MC＝0.4-P _LO-(PL _IPS+PL _CEM) (9)

Step 5: repeating step 1～4, the amount that carbonatite Compaction, intergranular particle pressolution and the cementation at calculating diverse location place reduces factor of porosity.