CN101487390A - Archie mode method for confirming initial oil saturation of oil layer - Google Patents

Abstract

The invention relates to an Archie mode method for determining oil layer initial oil saturation, comprising the following steps: (1) inspecting the structure of oil pool and the geological condition of a reservoir bed, and collecting relevant sampling data; (2) correcting initial oil saturation and initial water saturation data; (3) calculating the average value of the initial oil saturation or the initial water saturation according to a downhole single sand layer, namely, a substratum; (4) calculating the average value of average degree of porosity according to the single sand layer, namely, the substratum, and reading the corresponding stratum deep direction-finding resistivity data by well logging curve; (5) collecting the data and drawing; (6) establishing the Archie mode of different reservoir bed types for a single layer with approximate reservoir bed deposition and oil pool and reservoir formation characteristics; and (7) calculating the initial oil saturation for the unsampled oil layer requiring the calculation of the initial oil saturation by using the Archie saturation formula. The initial oil saturation calculated by applying the method has high precision.

Description

A kind of A Erqi mode method of definite oil reservoir initial oil saturation

Technical field:

The present invention relates to a kind of method that oil exploration and exploitation oil reservoir field and petroleum-in-place calculate, especially a kind of A Erqi mode method of definite oil reservoir initial oil saturation.

Background technology:

In blowhole, the volume of oil occupies the percentage of imitating voids volume and is called oil saturation, and the volume of oil occupies the percentage of imitating voids volume and is called initial oil saturation in the reservoir under reset condition.Because the initial oil saturation of oil reservoir is the important parameter estimating oil reservoir and calculate the reservoir geology reserves, always is subjected to the attention of domestic and international petroleum geology circle, on measuring method also in continuous development.

At first be to utilize oil-base mud to get core directly to measure original water saturation, all carried out the oil-base mud core work in the European and American countries and the former Soviet Union.European and American countries had developed the high-pressure sealed technology that core is directly measured fluid saturation of getting again afterwards.

In China, early 1960s carries out oil-base mud at Daqing oil field and gets core and directly measure initial oil saturation and succeed, and set up and be intended to get in the whole process of core, sampling, assay, guarantee primitiveness moisture in the core and a whole set of assay method more accurately.Because oil-base mud is got core and is high-pressure sealedly got the method expense costliness that core is directly measured oil saturation, can not carry out in a large number.External indirect method of having carried out many definite oil-containings, gas, water saturation again, as oil saturation and permeability graph of a relation method, capillary pressure method (centrifuge and mercury injection method) and geophysical log are explained and are sought.To the seventies in 20th century, particularly in the U.S., development and perfect hole geometry from the theory of oil and gas secondary migration, are having bigger progress aspect capillary pressure curve research oil-containing, gas, the water saturation using.

At present, ask for the oil reservoir oil saturation and mainly contain three kinds of Basic Ways, core is directly measured, and well log interpretation method and capillary pressure data are calculated.Though the accuracy that core is directly measured is higher, but the problem and the practical application of data quantity are restricted, setting up the original method that contains saturation ratio of indirect calculating uses the most general, Chang Yousan kind method: 1. empirical statistics method, utilize the direct initial oil saturation data of measuring of core of oil-base mud or sealed coring well exactly, the relation of foundation and conventional rerum natura (degree of porosity, permeability), or establishment oil column height and oil saturation plate etc.This method is simple and practical, but it depends on sealed coring well data and be only applicable to structural oil pool, and practical application is limited to.2. geophysical log method, it is to be theoretical foundation with the Archie formula, sets up and oil reservoir initial oil saturation relation by the resistivity logging data.Method commonly used has Archie formula method, short gradient apparent resistivity ratio chart method, resistivity Magnification chart method, revises A Erqifa etc.Because data, the method for well log interpretation oil saturation is the most extensive, generally need get the saturation data of core actual measurement and demarcate, and could guarantee to calculate accuracy and precision.3. test reservoir engineering method, utilize the process of modern experimental technique simulated oil expelling water to analyze the initial oil saturation of oil reservoir, commonly used have intrusive mercury curve and a phase permeability curve method.J function method, minimum pore throat radius method, oil column height method are arranged, producing water ratio and the original method such as saturation equation that contains, the general friendship of these methods is fit to structural deposit.

In a word, utilize the direct initial oil saturation of measuring of core of oil-base mud or sealed coring well, be considered to method the most accurately at present.In exploration phase based on lithologic deposit, oil-base mud or sealed coring well limited amount, the lithology factor makes that the initial oil saturation of oil reservoir and degree of porosity not exclusively are positive correlation, makes the initial oil saturation application of actual measurement be restricted.Past, a A Erqi constant was adopted in generally very big zone when using Archie formula and calculate the oil reservoir initial oil saturation: i.e. void index m, saturation index n and lithology factor a A Erqi parameter, the initial oil saturation precision of Ji Suaning is lower like this.

Summary of the invention:

The purpose of this invention is to provide sandstone oil field in the reservoir evaluation of exploration and exploitation, oil saturation data according to the sealed coring well analysis, foundation can be calculated the A Erqi pattern of oil reservoir initial oil saturation, and different patterns has the A Erqi constant of oneself: i.e. void index m, saturation index n and lithology factor a A Erqi parameter.The oil saturation data of sealing core drilling data actual measurement can be more widely used, and the oil reservoir initial oil saturation data of calculating are more accurate.

Technical scheme of the present invention is: this A Erqi mode method of determining the oil reservoir initial oil saturation comprises the following steps:

1. investigate the structure of oil reservoir, the geological conditions of reservoir, collect the effecive porosity get the oil reservoir that core records and air permeability, formation testing data, the dark direction finding resistance parameter of well logging, initial oil saturation and the original water saturation data that sealing core drilling is analyzed;

2. the initial oil saturation and the original water saturation data of sealing core drilling analysis are proofreaied and correct;

3. to the initial oil saturation data after proofreading and correct, be that substratum calculates initial oil saturation or water saturation average by single layer of sand in the well;

4. be that substratum calculates average pore average by above-mentioned single layer of sand, and read the resistivity data of layer depth direction finding accordingly by log;

5. by getting the core well final well report sedimentary micro that to collect above-mentioned single layer of sand be substratum, the fluid properties of regional oil column height, oil reservoir is drawn C-M figure, sandstone probability curve, peak dot pore throat radius figure, four sexual intercourse figure;

6. will become to hide the individual layer of feature by having close reservoir deposition and oil reservoir, statistics water saturation, average pore, oil reservoir true resistivity, formation water resistivity data, and difference substitution A Erqi saturation ratio formula, thereby obtain void index m, saturation index n and the lithology factor a A Erqi parameter of reservoir, set up the A Erqi pattern of different reservoir type;

7. ask for the oil reservoir of not coring of initial oil saturation for needs, compare by feature with the A Erqi mode layer, choose m, n, a parameter of approaching A Erqi mode layer, utilize average pore, oil reservoir true resistivity, the formation water resistivity data of this layer, the initial oil saturation that utilization A Erqi saturation ratio formula just can be calculated;

Above-mentioned when the m that obtains the different reservoir type, n, a A Erqi parameter, calculate definite by following formula:

$\log S_w=\frac{1}{n}\log R_w-\frac{1}{n}\log R_t-\frac{m}{n}\log \mathrm{\φ}+\frac{1}{n}\log a.$

The A Erqi pattern is to be elementary cell with a single sand body.At first with the oil saturation data of directly surveying, the A Erqi parameter that A Erqifa calculates this sand body is revised in utilization, mainly is void index m, saturation exponent n, lithologic index a, and this is one of free-revving engine of modeling.To reservoir characteristic core analysis, electric logging and some comprehensive study achievements of this sand body, portray comprehensively and describe then, mainly adopt following content:

First kind oil reservoir oil reservoir data

1. the regional background of oil reservoir: the sedimentary micro of construction location, reservoir, fault properties, regional oil column height.

2. reservoir parameter: effecive porosity, oil reservoir true resistivity, formation water resistivity, initial oil saturation.

3. oil reservoir feature: geothermal gradient, barometric gradient.

4. crude oil high pressure property: oil density, viscosity of crude, volume factor, oil-gas ratio, saturation pressure.

The second class achievement map

1. four sexual intercourse figure: reflection electrically, the best map of rerum natura, lithology and oiliness.

2. the sedimentary condition figure of reservoir: C--M figure, sandstone probability curve diagram, clay mineral content distribution map.

3. the pore structure figure of reservoir: peak dot pore throat radius and intrusive mercury curve figure

4. get core well drawing of site: intuitively reflect the construction location of this well in the basin.

The beneficial effect that the present invention had is: the present invention sets up on sealed coring or oil-base mud are got oil reservoir in the core well data, actual measurement oil reservoir by the sealing core drilling analysis contains the saturated with fluid degrees of data for basic, utilization well logging geology principle and A Erqi saturation ratio formula are set up the A Erqi pattern by m, n, a A Erqi parameter of asking for single reservoir.The A Erqi pattern of setting up can become the visual model of overall merit oil reservoir, is again the forward model that calculates new oil reservoir oil saturation.Determine the A Erqi mode method of oil reservoir initial oil saturation, owing to considered different reservoir and reservoir condition, microfacies according to sand body has been set up pattern respectively, make m, n, a A Erqi parameter on choosing more specifically, so the oil reservoir initial oil saturation precision of calculating is higher, especially expanded A Erqifa and calculated the scope of application that contains the fluid saturation method, it is not obvious to be more suitable for regional structure, the oil district that takes as the leading factor with lithological pool.

Description of drawings:

No. 3 floor of Fig. 1 DQ area F floor Z262 well four sexual intercourse figure;

Radius figure is shouted in No. 3 range upon range of mountains point holes of F floor Z262 well, Fig. 2 DQ area;

No. 3 floor sandstone of Fig. 3 DQ area F floor Z262 well probability graph;

No. 3 floor C-M figure of Fig. 4 DQ area F floor Z262 well.

The specific embodiment:

The invention will be further described below in conjunction with embodiment: this A Erqi mode method of determining the oil reservoir initial oil saturation comprises the following steps:

The first step is investigated the structure of oil reservoir, the geological conditions of reservoir, collects permeability, dark side direction resistivity, the sealing core drilling analysis of getting the oil reservoir that core records and contains data such as fluid saturation;

The f oil reservoir in DQ oil field is that fluvial facies deposit is main reservoir depositional environment, and the structure amplitude is little, characteristics such as single thin layer.The initial oil saturation of oil reservoir changes greatly, mainly is subjected to factor affecting such as reservoir sand body rerum natura, oil column height.

We to sealed coring and oil-base mud get the core well by layer position according to effective pay thickiness, the rerum natura of different regions, electrically standard has been carried out the effective thickness division.And then carry out initial oil saturation according to substratum and add up.Get sandwich layer position, the number of plies and effective number of plies etc. to 15 mouthfuls of more full wells of data gather.Statistics shows, 15 mouthfuls of sealed corings or oil-base mud are got the core well, totally 152 layers, are divided into 46 layers (table 1) of effective layer of analysing oil saturation.

Oil-base mud is cored and sealed coring well MSDS table 1

Sequence number	Year	Pound sign	Core layer position	The number of plies	Effective number of plies	The invalid number of plies and reason
							1	1994	Ta212	S.P.FY	11	6	5 layer water saturations are higher.
2	2000	Gu148	H.P	11	0	11 layer water saturations are higher.
							3	2000	Gu151	H.P	10	0	7 layer water saturations are higher, do not core for 3 layers.
4	1998	Gu933	G	17	3	14 layer water saturations are higher.
							5	1999	Gu139	H.P	14	1	10 layer water saturations are higher, do for 3 layers.
6	1997	Long10-08	S.P.G	8	0	7 layer water saturations are higher, do not core for 1 layer.
							7	1993	Yuan158	FY		5	2	2 layer water saturations are higher, and 1 layer of oil is higher.
8	1989	Zh251	P.FY		6	3									3 layer water saturations are higher.
							9	1992	Mao503	F	11	3	2 layer water saturations are higher, and 3 layers of oil are higher, do not core for 3 layers.
10	1989	Shu131	F	12	3	1 layer water saturation is higher, does, does not core for 4 layers for 4 layers.
							11	1990	Shu113	P.F	14	3	6 layer water saturations are higher, do for 5 layers.
12	1996	Tai106	P.FY		9	8								1 layer water saturation is higher.
							13	1997	Zhao262	P.F	5	5	But oil saturation is higher.
14	1995	Da424	H.P	9	5	3 layer water saturations are higher, 1 layer of n.s.
							15	1992	Chao964	FY		10	4	6 layer water saturations are higher.
				152	46

In second step, analysis contains data such as fluid saturation and proofreaies and correct to sealing core drilling;

15 mouthfuls of sealed corings or oil-base mud are got the oil saturation and the water saturation input database of core well, and proofread and correct the back oil saturation and the water saturation sum is 100% with computer software, with DQ oil field Y158 well partial data is example, DQ oil field Y158 well sealed coring well profit saturation data table (table 2).

DQ oil field Y158 well sealed coring well profit saturation data table table 2

Sample number	Degree of porosity (%)	Permeability (md)	The actual measurement water saturation	Actual measurement oil saturation (%)	Water saturation behind the school (%)	Oil saturation behind the school (%)
							1	11.67	0.27	16.8	65.7	22.39	77.61
2	14.57	6.23	8.6	65.5	12.90	87.10
							3	14.86	0.84	22.4	53	32.29	67.71
4	13.02	0.44	31.8	53.7	40.05	59.95
							5	16	1.47	20	50.4	30.92	69.08
6	15.86	1.97	21	53.1	30.85	69.15
							7	13.82	2.88	26.4	49.4	37.61	62.39
8	13.81	2.94	20.4	56.5	28.94	71.06
							9	12.54	1.95	26.3	57.9	33.88	66.12
10	15.35	1.41	40.6	32.6	58.42	41.58
							11	14.46	3.23	21.3	58	29.29	70.71
12	13.94	2.09	34.3	43.8	46.91	53.09
							13	13.7	1.16	22.9	58.8	30.52	69.48
14	13.86	2.53	28.6	51.2	38.66	61.34
							15	13.82	1.39	18.8	61.7	25.58	74.42
16	13.35	0.37	22.5	58.5	30.26	69.74
							17	12.79	2.68	26	57	33.97	66.03
18	12.79	0.49	25.9	59	33.12	66.8R
							19	15.55	2.78	10.6	56.1	17.57	82.43

In the 3rd step,, press single layer of sand (substratum) statistical average initial oil saturation or water saturation in the well to the data after proofreading and correct;

15 mouthfuls of sealed coring well are carried out effective thickness divide, added up degree of porosity, permeability, initial oil saturation totally 46 layers (table 3) by individual layer.

In the 4th step, press above-mentioned single layer of sand (substratum) statistical average degree of porosity, and read the dark direction finding resistivity data of equivalent layer; To 46 layers on effective layer of analyzing oil saturation, dark side direction resistivity, average pore (table 3) have been read.

DQ oil field sealed coring well individual layer oil saturation and resistivity data table table 3

Pound sign	Level number	Degree of porosity (%)	Permeability (md)	Dark side direction resistivity (Ω m)	Oil saturation behind the school (%)
						Y158	13	15.5	2.63	63.0	82.4
Y158	15	13.3	0.56	40.0	69.7
						Y158	16	12.5	1.95	38.0	66.12
Y158	18	16.3	1.46	42.0	69.3
						Ta212	29	10.86	0.8	38.0	55.3
Ta212	30	10.7	0.62	30.0	71.0
						Ta212	32	11.96	0.87	60.0	71.0
Ta212	40	10.10	0.52	30.0	63.5
						Mao503	21	11.63	0.70	19.0	58.3
Mao503	22	13.13	1.81	30.0	75.0
						Mao503	23	13.37	0.71	17.0	66.6
...	....

The 5th step, the sedimentary micro of collecting above-mentioned single layer of sand (substratum), radius figure, four sexual intercourse figure are shouted in the fluid properties of regional oil column height, oil reservoir, drafting C-M figure, sandstone probability curve, peak dot hole.

Effective layer is drawn four sexual intercourse figure for 46 layers, peak dot pore throat radius figure etc., the sedimentary micro of having added up single layer of sand of each oil reservoir, oil column height (Fig. 1～Fig. 4).

The 6th step, to become to hide the individual layer of feature by having close reservoir deposition and oil reservoir, statistics water saturation, average pore, oil reservoir true resistivity, formation water resistivity data, and difference substitution A Erqi saturation ratio formula, thereby obtain the A Erqi parameter such as m, n, a of different reservoir type, set up A Erqi pattern storehouse (table 4), this district formation water resistivity 0.9 Ω m.

DQ area F oil reservoir A Erqi pattern and parametric data table 3

Water saturation, average pore, oil reservoir true resistivity, formation water resistivity data difference substitution A Erqi saturation ratio formula with 46 layers on effective layer, thereby obtain the A Erqi parameter such as m, n, a of different reservoir type, set up the A Erqi pattern of different reservoir.

The 7th step, calculate the not core hole layer of initial oil saturation for needs, compare by annotate features such as height with four sexual intercourse, the oil of the full mode layer of A Erqi, choose m, n, a parameter of approaching A Erqi mode layer, in conjunction with average pore, oil reservoir true resistivity, the formation water resistivity data of this layer, utilize A Erqi saturation ratio formula just can calculate not core the initial oil saturation of layer.

At the F in bycg area oil reservoir, No. 20 floor of ta211 well are fluvial sandstones, and it highly is 70m that the oil of this well place oil reservoir is annotated, and degree of porosity is 12%.From all kinds of comparison figures and number 2 similarly, so adopting the parameter m of the A Erqi pattern of numbering 2 is 2.25, n is 1.9, and a is 0.56, and resistivity is 18, and Rw is 0.9 Ω m.The substitution Archie formula:

$\log S_w=\frac{1}{n}\log R_w-\frac{1}{n}\log R_t-\frac{m}{n}\log \mathrm{\φ}+\frac{1}{n}\log a$

: Sw=52

So＝100-Sw＝48

So the initial oil saturation of No. 20 floor of ta211 well is 64%.

Claims (2)

1. the A Erqi mode method of a definite oil reservoir initial oil saturation is characterized in that, this method comprises the following steps:

1. investigate the structure of oil reservoir, the geological conditions of reservoir, the dark direction finding resistance parameter of the effecive porosity of collection core hole oil reservoir and air permeability, well-log information, initial oil saturation and the original water saturation data that sealing core drilling is analyzed;

2. the initial oil saturation and the original water saturation data of sealing core drilling analysis are proofreaied and correct;

3. to the initial oil saturation data after proofreading and correct, be that substratum calculates initial oil saturation or water saturation average by single layer of sand in the well;

4. be that substratum calculates average pore average by above-mentioned single layer of sand, and read the resistivity data of layer depth direction finding accordingly by log;

5. by getting the core well final well report sedimentary micro that to collect above-mentioned single layer of sand be substratum, the fluid properties of regional oil column height, oil reservoir is drawn C-M figure, sandstone probability curve, peak dot pore throat radius figure, four sexual intercourse figure;

6. will become to hide the individual layer of feature by having close reservoir deposition and oil reservoir, statistics water saturation, average pore, oil reservoir true resistivity, formation water resistivity data, and difference substitution A Erqi saturation ratio formula, thereby obtain void index m, saturation index n and the lithology factor a A Erqi parameter of reservoir, set up the A Erqi pattern of different reservoir type;

7. ask for the oil reservoir of not coring of initial oil saturation for needs, compare by feature with the A Erqi mode layer, choose m, n, a parameter of approaching A Erqi mode layer, utilize average pore, oil reservoir true resistivity, the formation water resistivity data of this layer, the initial oil saturation that utilization A Erqi saturation ratio formula just can be calculated.

2. according to the A Erqi mode method of stand oil layer original oil saturation really described in the claim 1, it is characterized in that: when the m that obtains the different reservoir type, n, a A Erqi parameter, calculate by following formula and to determine:

$\log S_w=\frac{1}{n}\log R_w-\frac{1}{n}\log R_t-\frac{m}{n}\log \mathrm{\φ}+\frac{1}{n}\log a---\left(1\right).$

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