Fast and not expensive formation evaluation
We offer new fast and not expensive technique for determination and quantitative evaluation of granular formations with complicated polymineral structure. This technique is not required preliminary accumulation of large volume of empiric petrophysical information for concrete objects. The technique is based on principle of petrophysical filtration of geological section.
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The tasks of formation determination and evaluation are solved simultaneously as criterions are quantitative parameters such as dynamic and effective porosity (with permeability evaluation). These parameters define the quality of formation as a hydrocarbon collector and are determined without complicated phase of total porosity evaluation. For polymineral formations total porosity could be an absolutely uninformative petrophysical parameter.
If any formation we study enriched with rigid organic substance Natural Gamma Spectralog data allow to overcome difficulties are caused by necessity anomalous properties calculations (density, hydrogen index, gamma-activity).
The diagrams of dynamic (effective) porosity have high vertical resolution and high differentiation due to radically increase correlation as well as determination of forming conditions (indications of transgressions and regressions).
This technique was not published but there are few references about some aspects of this method
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Porosity evaluation technique from spectral and integral natural gamma ray log data
This technique has following principle advantages:
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base (supporting) formations are not required;
- interpretation parameter for integral gamma ray log is a petrophysical
magnitude - uranium equivalent (eU), rigorous petrophysical model for eU
specified;
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open and cased hole porosity evaluation, while drilling real time evaluation is
possible;
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mud and formation water mineralizations are not affected;
- zone of penetration is not affected;
- more accurate effective thickness determination due to maximum vertical resolution of spectral and integral natural gamma ray log among "porosity logs" (SP, Density, Neutron etc.);
- this technique and algorithm remain in force if quantitative collector indications are absent or violent (hole diameter narrowing, SP potentials violent if mineralized polymineral mud used etc.);
- hole construction, diameter changes, mud, mud cake and cement density and gamma-activity, casing thickness and composition are took into account, and the technique and algorithm provide calculations without any special additional corrections;
- interpretation algorithm valid for any kind of logging tools, all results could be compare as the interpretation result is not dependent on type of tool;
- preliminary accumulation of large volume of empiric petrophysical information such as "core analysis - core analysis" or "core analysis - log analysis" charts for "count rate - clayness" or "count rate - porosity" charts is not required.
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Adaptive logging data interpretation technique with geological intelligence
The technique is based on:
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the principle of adaptivity for every interpretation module instead of
correction charts;
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rigorous petrophysical models instead of empiric correlation dependences;
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metrological supplying for gamma-activity logs based on metrological
characteristics (radial sensitivity, for example);
- communication between separate interpretation modules.
Precision of quantitative interpretation results are provided by:
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the tuning of algorithms in individual metrological characteristics of logging
tools;
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algorithmic calculations of intermediate zones properties;
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the technological tuning of algorithms in force formation evaluation methods
(logging - force - logging);
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using of rigorous petrophysical models instead of empiric correlation
dependences;
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adaptive technology of complex interpretation (log analysis);
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using of cyclemetric analysis.
The adaptive interpretation technology of logging data has not any analogues.
There are three main differences of this technique from all other known ones.
First of all, this analysis procedures are not required using of hypothetical
dependences (gamma-activity vs clayness or porosity vs hydrogen index, for
example). Secondly, all formation components content (matrix, clay, fluid, SOM,
coal etc.) are determined simultaneously without following corrective action.
Petrophysical and geochemical regularity are emerged as the analysis result.
This technique allows:
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to determinate and quantitative evaluate untraditional reservoirs, estimate the
dynamic porosity taking in account SOM, boron, pyrite, bitumen, zeolite
contents (if there is Natural Gamma Spectralog data in the logging complex);
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to classify reservoirs on store space structure (if dynamic force formation
evaluation methods are used);
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to determinate zones of artificial splitting or colmatation (if density log is
used);
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to estimate mineralogical and granular clayness, different minerals contents
affect on reservoir properties in the forming of deposit and due to production
(if there is Natural Gamma Spectralog data in the logging complex);
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to determinate absolute geological age of formations from wire-logging data and
the results of their petrophysical interpretation;
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to display sludge breaks according the data even from one well.
Interpretation algorithms are universal for any kind of logging tools with
different constructional parameters in any environment conditions.
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