CN105804734A - Method for identifying thickened oil reservoir by utilizing nuclear magnetic resonance well logging - Google Patents

Abstract

The invention discloses a method for identifying a thickened oil reservoir by utilizing nuclear magnetic resonance well logging and belongs to the field of reservoir fluid identification.The method comprises the steps that a well having nuclear magnetic resonance well logging data is processed to obtain a standard T2 distribution spectrum; the nuclear magnetic porosity of the reservoir is calculated, and a nuclear magnetic T2 spectrum cutoff value method is utilized to calculate irreducible water saturation SBVI; a spectrum coefficient method is utilized to calculate irreducible water saturation SSBVI; finally, reservoir fluid identification factors are calculated; a fluid identification chart is established according to the fluid identification factors, and accordingly a reservoir fluid is accurately judged.The method utilize the characteristic that the two calculated irreducible water saturations have remarkable difference when thickened oil exists in the reservoir to effectively identify the reservoir, can adopt a method of utilizing the nuclear magnetic T2 spectrum cutoff value method and the spectrum coefficient method to calculate the difference of the irreducible water saturations to achieve accurate and reliable identification of the thickened oil reservoir in a thickened oil distribution area and is an effective fluid identification method for exploration and evaluation of large-area thickened oil reservoirs of our country at present.

Description

A kind of method utilizing nuclear magnetic resonance log identification thick oil reservoir

Technical field

The present invention relates to fluid identification of reservoir field in formation testing exploration, particularly to a kind of nmr logging method identifying thick oil reservoir.

Background technology

The fluid identification of thick oil reservoir is one of difficult problem that well log interpretation is evaluated, and nuclear magnetic resonance log is a kind of logging method of the natural content of hydrogen in Study of Fluid and occurrence status, is the currently the only logging method that can evaluate crude oil physical property.But after thick oil reservoir great many of experiments is confirmed that viscous crude (viscosities il > 50cP/50 DEG C) is saturated to rock sample, its T₂Spectrum is substantially distributed in constraint liquid scope, when crude oil reaches certain viscosity, and the T of viscous crude₂Value is even also little than constraint fluid, is now difficult to distinguish viscous crude and constraint fluid information, and this is also the technical limitations of current one-dimensional nuclear magnetic resonance well logging recognition thick oil reservoir.

Utilizing nuclear magnetic resonance log identification thick oil reservoir forefathers to do some research work from nuclear magnetic resonance experiment and actual nuclear magnetic resonance log, what Zong Bin etc. passes through nuclear magnetic resonance experiment and finds the T of viscous crude₂Along with the rising of temperature, spectral peak occurs that division shows as multimodal feature, carry out qualitative recognition thick oil reservoir with this；Bu Ling Radix Mume is according to the different T of NMR logging data₂Distributional pattern and T₂The size of peak value differentiates thick oil reservoir qualitatively；Shao Weizhi etc. summarize the method that utilizes nuclear magnetic resonance log identification thick oil reservoir by the classification of reservoir pore space is divided into micro--fine pore with in-macrovoid contrasts water layer and oil reservoir standard T respectively₂Spectrum, difference spectrum signal and shifting spectrum signal feature difference identify thick oil reservoir.

Summary of the invention

In order to solve cannot utilize in prior art the problem of conventional nuclear magnetic resonance log identification thick oil reservoir, the present invention provides one to utilize T₂Cutoff and spectral coefficient method calculate the method that reservoir irreducible water saturation identifies thick oil reservoir.It is overlapping with constraint fluid signal and cause the unfavorable factor of viscous crude signal None-identified that this method is capable of avoiding viscous crude signal.Calculate irreducible water saturation by two kinds of methods to come quickly in the difference of water layer Yu heavy oil tested layer, identify thick oil reservoir accurately.

It is an object of the invention to be realized by following technical proposals.

A kind of method utilizing nuclear magnetic resonance log identification thick oil reservoir, comprises the steps:

Step (1), carries out process to the well with nuclear magnetic resonance log data and obtains standard T₂Distribution profile；

Step (2), calculates the nuclear-magnetism porosity of reservoirAnd utilize nuclear-magnetism T₂Spectrum cutoff method and spectral coefficient method calculate the T of reservoir respectively₂Spectrum cutoff method irreducible water saturation S_BVIWith spectral coefficient method irreducible water saturation S_SBVI；

Step (3), utilizes the reservoir nuclear-magnetism porosity required by step (2)And T₂Spectrum cutoff method irreducible water saturation S_BVIWith spectral coefficient method irreducible water saturation S_SBVI, calculate fluid identification of reservoir factor k；

Step (4), with the irreducible water saturation S of spectral coefficient method_SBVIFor abscissa, fluid identification of reservoir factor k is that vertical coordinate sets up fluid identification plate, respectively obtains fluid oil reservoir, water layer and dried layer region；

Step (5), for the new well of properties of fluid in bearing stratum to be identified, according to the spectral coefficient method irreducible water saturation S that step (2), step (3) calculate_SBVIWith fluid identification factor k, then the result of calculation of target zone position is projected on cross plot, the fluid of thick oil reservoir is made identification.

Further, when carrying out step (1) operation, Nuclear Magnetic Resonance Logging need to be processed and obtain standard T₂Spectrum, processing method is for P type nuclear-magnetism reference " DPP nuclear-magnetism treatment technology handbook ".

Further, in step (2), calculate the nuclear-magnetism porosity of reservoirFront 5 the echo-signal invertings of echo are utilized to obtain, with specific reference to " DPP nuclear-magnetism treatment technology handbook ".

Further, in step (2), T is utilized₂Cutoff method calculates irreducible water saturation S_BVI, calculated by below equation and obtain:

$S_{BVI}=\frac{{\∫}_{T_{2\min }}^{T_{2cutoff}}{\mathrm{\φ}}_{i}d\left(T_2\right)}{{\∫}_{T_{2\min }}^{T_{2\max }}{\mathrm{\φ}}_{i}d\left(T_2\right)}*100\%$

In formula, S_BVIFor nuclear-magnetism T₂The irreducible water saturation of cutoff method；T_2minFor nuclear magnetic resonance, NMR standard T₂The minimum time value of distribution；T_2maxFor nuclear magnetic resonance, NMR standard T₂The maximum time value of distribution；T_2cutoffIt is T₂Cutoff；φ_iFor nuclear magnetic resonance, NMR standard T₂Each T in distribution₂Amplitude corresponding to time.

Further, in step (2), spectral coefficient method is utilized to calculate irreducible water saturation S_SBVI, calculated by below equation and obtain:

$W_i=\frac{1}{{\mathrm{mT}}_{2i}+b}$

In formula, S_SBVIIrreducible water saturation for spectral coefficient method；W_iFor nuclear magnetic resonance, NMR standard T₂T in distribution_2iWeight coefficient corresponding to component irreducible water；I=1,2 ..., n；T_2iIt is the T relevant with i-th component₂Relaxation time；M, b are undetermined coefficients, relevant with pore geometry and Free water water-column；N is the number of component；φ_iFor T₂T in distribution_2iAmplitude corresponding to component.

Further, in step (3), calculate fluid identification of reservoir factor k and obtained by below equation calculating:

In formula,For reservoir nuclear-magnetism porosity computed in step (2), unit is decimal；S_BVIFor step (2) utilizes nuclear-magnetism T₂Cutoff method irreducible water saturation, unit is percent；S_SBVIFor the spectral coefficient method irreducible water saturation utilizing spectral coefficient method to calculate in step (2), unit is percent.

Further, in described step (4), set up fluid identification plate be the nuclear magnetic signal with viscous crude Yu irreducible water completely overlapped and both calculate the difference of the physical model of irreducible water saturation and computation model, make the irreducible water saturation calculated both when reservoir exists viscous crude there is significant difference, utilize this species diversity that thick oil reservoir is effectively identified.

Region is grown viscous crude and has the well of NMR logging data and be respectively adopted T by the technical scheme that the embodiment of the present invention provides₂Cutoff method and spectral coefficient method calculate the irreducible water saturation of reservoir, owing to the nuclear magnetic signal of viscous crude Yu irreducible water is completely overlapped and both calculate the physical model difference with computation model of irreducible water saturation, make the irreducible water saturation calculated both when reservoir exists viscous crude there is significant difference, utilize this species diversity that thick oil reservoir is effectively identified.The method achieve and utilize T₂Cutoff method and spectral coefficient method calculate the reservoir irreducible water saturation difference at water layer Yu heavy oil tested layer, Quick thick oil reservoir；Avoid because the viscous crude relaxation time is too short, the problem causing conventional nuclear magnetic resonance log None-identified；It is capable of thick oil reservoir is accurately and reliably identified, provides effective viscous crude Fluid Identification Method for the large-area petroleum reservoir exploration of current China and reservoir evaluation.

Accompanying drawing explanation

In order to be illustrated more clearly that the technical scheme in the embodiment of the present invention, below the accompanying drawing used required during embodiment is described is briefly described, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the premise not paying creative work, it is also possible to obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is the method flow diagram identifying thick oil reservoir that the embodiment of the present invention provides；

Fig. 2 is the fluid identification plate that the embodiment of the present invention is set up；

Fig. 3 is a bite new well fluids identification application design sketch that the embodiment of the present invention provides.

Detailed description of the invention

For making the object, technical solutions and advantages of the present invention clearly, below in conjunction with accompanying drawing, embodiment of the present invention is described further in detail.

Shown in Fig. 1, give the method that the present invention utilizes nuclear magnetic resonance log identification thick oil reservoir, comprise the steps:

Step (1), carries out process to the well with nuclear magnetic resonance log data and obtains standard T₂Distribution profile；

Step (2), calculates the nuclear-magnetism porosity of reservoirAnd utilize nuclear-magnetism T₂Spectrum cutoff method and spectral coefficient method calculate the T of reservoir respectively₂Spectrum cutoff method irreducible water saturation S_BVIWith spectral coefficient method irreducible water saturation S_SBVI；

Step (3), utilizes the reservoir nuclear-magnetism porosity required by step (2)And T₂Spectrum cutoff method irreducible water saturation S_BVIWith spectral coefficient method irreducible water saturation S_SBVI, calculate fluid identification of reservoir factor k；

Step (4), with the irreducible water saturation S of spectral coefficient method_SBVIFor abscissa, fluid identification of reservoir factor k is that vertical coordinate sets up fluid identification plate, respectively obtains fluid oil reservoir, water layer and dried layer region；

Step (5), for the new well of properties of fluid in bearing stratum to be identified, calculates its spectral coefficient method irreducible water saturation S according to step (2), step (3)_SBVIWith fluid identification factor k, then the result of calculation of target zone position is projected on cross plot, the fluid of thick oil reservoir is made identification.

The present invention chooses North China Oilfield Lixian Slope and grows certain fault block of thick oil reservoir as embodiment.Specifically implement in accordance with the following steps.

Step (1), has the well of nuclear magnetic resonance log data and carries out process and obtain standard T this area₂Distribution profile, these district's nuclear magnetic resonance log data are measured by Halliburton's P type nuclear magnetic resonance log instrument and middle oil well logging MRT nuclear magnetic resonance log instrument, seek T echo is carried out inversion procedure₂Time spectrum, is respectively adopted DPP and LEAD3.0 log interpretation software and processes.

Step (2), utilizes front 5 echo-signals in the echo that nuclear-magnetism measured by DPP software to calculate reservoir porosityTo the standard T obtained₂Spectrum application T₂Cutoff method calculates irreducible water saturation, is specifically calculated according to equation below:

$S_{BVI}=\frac{{\∫}_{T_{2\min }}^{T_{2cutoff}}{\mathrm{\φ}}_{i}d\left(T_2\right)}{{\∫}_{T_{2\min }}^{T_{2\max }}\mathrm{\φ}d\left(T_2\right)}*100\%$

Wherein, S_BVIFor nuclear-magnetism T₂The irreducible water saturation of cutoff method, T_2minFor nuclear magnetic resonance, NMR standard T₂Distribution minimum time value, 0.3ms；T_2maxFor nuclear magnetic resonance, NMR standard T₂Distribution maximum time value, 3000ms；T_2cutoffIt is T₂Cutoff, 23ms；φ_iFor nuclear magnetic resonance, NMR standard T₂T in distribution_2iAmplitude corresponding to component.

To the standard T obtained₂Spectrum spectrum of use Y-factor method Y calculates irreducible water saturation, is specifically calculated according to equation below:

$W_i=\frac{1}{{\mathrm{mT}}_{2i}+b}$

Wherein, S_SBVIFor the irreducible water saturation of spectral coefficient method, W_i(i=1,2 ..., 200) for nuclear magnetic resonance, NMR standard T₂T in distribution_2iProportionality coefficient corresponding to component irreducible water, T_{2, i}It is the T relevant with i-th component₂In the relaxation time, m takes 0.0618, b, and to take 1, n be that the number of component takes 200, φ_iFor T₂T in distribution_2iAmplitude corresponding to component.

In step (3), utilize calculating in step (2)S_BVIAnd S_SBVI, calculate fluid identification of reservoir factor k and obtained by below equation calculating:

Step (4), with S_SBVIFor abscissa, k is that vertical coordinate makes fluid identification plate, as shown in Figure 2.

Step (5), carries out fluid identification to this new well of district's a bite, as it is shown on figure 3, the 3rd road is standard T₂Spectrum, the 4th road is the irreducible water saturation that two kinds of methods calculate, wherein S_BVIFor T₂The irreducible water saturation that cutoff calculates, S_SBVIFor the irreducible water saturation that spectral coefficient calculates, fluid identification factor k=2.6, the S that No. 35 floor calculate_SBVI=46% this reservoir is reservoir characteristics, No. 39 layer fluid recognition factor k=-1.3, S_SBVI=34% this layer is water layer feature, is all confirmed through formation testing.

When reservoir development viscous crude its nuclear magnetic signal often with irreducible water signal overlap, limit the nuclear magnetic resonance log effective identification to thick oil reservoir, can be seen that from this embodiment and utilize two kinds of differences calculating reservoir irreducible water saturation model result of calculation can effectively identify thick oil reservoir, namely show as difference in both water layers result of calculation small, and the reservoir grown at viscous crude shows as obvious difference.

The invention described above embodiment sequence number, just to describing, does not represent the quality of embodiment.

The technical scheme above embodiment of the present invention provided is described in detail, principle and the embodiment of the embodiment of the present invention are set forth by specific case used herein, and the explanation of above example is only applicable to help to understand the principle of the embodiment of the present invention；Simultaneously for one of ordinary skill in the art, according to the embodiment of the present invention, all will change in detailed description of the invention and range of application, in sum, this specification content should not be construed as limitation of the present invention.

Claims (7)

1. the method utilizing nuclear magnetic resonance log identification thick oil reservoir, it is characterised in that comprise the steps:

Step (1), carries out process to the well with nuclear magnetic resonance log data and obtains standard T₂Distribution profile；

Step (2), calculates the nuclear-magnetism porosity of reservoirAnd utilize nuclear-magnetism T₂Spectrum cutoff method and spectral coefficient method calculate the T of reservoir respectively₂Spectrum cutoff method irreducible water saturation S_BVIWith spectral coefficient method irreducible water saturation S_SBVI；

Step (3), utilizes the reservoir nuclear-magnetism porosity required by step (2)And T₂Spectrum cutoff method irreducible water saturation S_BVIWith spectral coefficient method irreducible water saturation S_SBVI, calculate fluid identification of reservoir factor k；

Step (4), with the irreducible water saturation S of spectral coefficient method_SBVIFor abscissa, fluid identification of reservoir factor k is that vertical coordinate sets up fluid identification plate, respectively obtains fluid oil reservoir, water layer and dried layer region；

Step (5), for the new well of properties of fluid in bearing stratum to be identified, according to the spectral coefficient method irreducible water saturation S that step (2), step (3) calculate_SBVIWith fluid identification factor k, then the result of calculation of target zone position is projected on cross plot, the fluid of thick oil reservoir is made identification.

2. the method for claim 1, it is characterised in that in described step (1), carries out inversion procedure to the well with nuclear magnetic resonance log data and obtains standard T₂Spectrum, processing method carries out according to " DPP nuclear-magnetism treatment technology handbook ".

3. the method for claim 1, it is characterised in that in described step (2), calculates the nuclear-magnetism porosity of reservoirUtilize front 5 the echo-signal invertings of echo to obtain, specifically carry out according to " DPP nuclear-magnetism treatment technology handbook ".

4. the method for claim 1, it is characterised in that in described step (2), utilize T₂Cutoff method calculates irreducible water saturation S_BVI, calculated by below equation and obtain:

$S_{BVI}=\frac{{\∫}_{T_{2\min }}^{T_{2cutoff}}{\mathrm{\φ}}_{i}d\left(T_2\right)}{{\∫}_{T_{2\min }}^{T_{2\max }}{\mathrm{\φ}}_{i}d\left(T_2\right)}*100\%$

In formula, S_BVIFor nuclear-magnetism T₂The irreducible water saturation of cutoff method；T_2minFor nuclear magnetic resonance, NMR standard T₂The minimum time value of distribution；T_2maxFor nuclear magnetic resonance, NMR standard T₂The maximum time value of distribution；T_2cutoffIt is T₂Cutoff；φ_iFor nuclear magnetic resonance, NMR standard T₂Each T in distribution₂Amplitude corresponding to time.

5. the method for claim 1, it is characterised in that in described step (2), utilizes spectral coefficient method to calculate irreducible water saturation S_SBVI, calculated by below equation and obtain:

$W_i=\frac{1}{{\mathrm{mT}}_{2i}+b}$

In formula, S_SBVIIrreducible water saturation for spectral coefficient method；W_iFor nuclear magnetic resonance, NMR standard T₂T in distribution_2iWeight coefficient corresponding to component irreducible water；I=1,2 ..., n；T_2iIt is the T relevant with i-th component₂Relaxation time；M, b are undetermined coefficients, relevant with pore geometry and Free water water-column；N is the number of component；φ_iFor T₂T in distribution_2iAmplitude corresponding to component.

6. the method for claim 1, it is characterised in that in described step (3), is calculated fluid identification of reservoir factor k and is obtained by below equation calculating:

In formula,For reservoir nuclear-magnetism porosity, unit is decimal；S_BVIFor T₂Cutoff method irreducible water saturation, unit is percent；S_SBVIFor spectral coefficient method irreducible water saturation, unit is percent.

7. the method for claim 1, it is characterized in that, in described step (4), set up fluid identification plate be the nuclear magnetic signal with viscous crude Yu irreducible water completely overlapped and both calculate the difference of the physical model of irreducible water saturation and computation model, make the irreducible water saturation calculated both when reservoir exists viscous crude there is significant difference, utilize this species diversity that thick oil reservoir is effectively identified.