SOFTWARE & HARDWARE COMPLEXES FOR PETROLEUM BOREHOLES

Software & hardware complexes for petroleum boreholes investigation using spectrometric modifications of gamma logging and pulsed neutron gamma logging

Information capabilities of gamma spectrometric technique

Spectrometry of natural (NGR) and neutron-induced gamma radiation: inelastic scattering gamma radiation and neutron capture gamma radiation (ISGR and NCGR), as well as induced gamma radiation (IGR) gives the opportunity to determine concentrations of elements forming the rock matrix and fluid (H, C, O, Na, Mg, Al, Si, Ca, Fe), as well as some trace elements (U (Ra), Th, K, Cl). Based on this one can determine mineralogical composition of matrix and components of formation fluid through measurements in an open or cased borehole. Components of pore fluid are measured regardless of water mineralization upon basic fluid forming elements (H, C, O).

Transition from integral to spectrometric modifications of gamma well-logging (GL-S) and pulsed neutron gamma well-logging (PNGL-S) drastically enhances their information capabilities and improves effectiveness of exploration and development geophysics, especially in complicated geological conditions. This transition preserves all capabilities of integral modifications, however spectrometric modifications improve the credibility and reliability of measuring such integral characteristics of the rock as integral gamma activity, clayiness, porosity, capture macrosection or thermal neutron lifetime. There is no need to slow down the logging speed compared to integral methods.

Gamma spectrometric software & hardware complexes

Practical opportunity to develop geophysical spectrometric gamma hardware with good metrological and operational features has emerged in the geophysical hardware manufacturing industry due to development of modern microelectronics, effective gamma spectrometric detectors (GSO, BGO), high frequency neutron generators and digital systems for analyzing, storing and transmitting spectrometric data.

Transmission to digital geophysical stations and computerization of development geophysics were the major prerequisites for industrial development of gamma spectrometric methods.

Modern geophysical gamma-spectrometric measurement systems are software and hardware complexes, where the software serves not only for measurement result processing, but also executes a significant part of functions, previously associated with the hardware. The role of the software in gamma spectrometric well-logging and qualitative determination of interpretation parameters can be compared with the role of the hardware. Final processing and geologic and geophysical interpretation require sophisticated software, which gives a great input to quality and robustness of results.

Gamma spectrometric software and hardware complexes with AINGK-89S, AGK-89S and AINK-89S equipment

Presented below are the specifications of gamma spectrometric software & hardware complexes (SHC) with AINGK-89S, AGK-89S and AINK-89S equipment that implements spectrometric modifications of gamma well-logging and pulsed neutron gamma well-logging.

The tools widely incorporate modern erasable programmable logic devices (EPLD). AINGK-89S and AINK-89S incorporate temperature-controlled detection units with BGO crystals. AINGK-89S and AINK-89S are operated together with high frequency neutron generators of ING-061-10 type. The equipment has analog-to-digital convertion with 1024 quantization level that allows correcting the energy scale drift by the software with high precision (5 keV for ISGR and RCGR and 0.6 keV for natural gamma radiation spectra).

All SHC use unified software adapted for the specific method and tool type.

Metrological support for each tool type is provided using physical and mathematical modeling and includes standard spectra libraries, used for measurement result processing.

	Software and hardware complex with gamma spectrometric equipment AINGK-89S

Purpose: Software and hardware complex (SHC) with AINGK-89S equipment is designed to investigate boreholes during exploration and development control at petroleum fields using pulsed neutron gamma well-logging and carbon-oxygen logging (C/O logging) in order to measure the collector oil-saturation regardless of water mineralization.

Information capabilities: As the result of data processing the following geologic and geophysical characteristics of layers are obtained:

• relative concentrations of main mineral components of rock matrix;
• hydrogen index;
• macroscopic capture section or thermal neutron lifetime;
• oil saturation factor;
• gas saturation factor.

Measurement conditions: Measurements are made in cased holes with interior diameter greater than 127 mm against non-perforated layers with temperature up to +120^îC and hydrostatic pressure up to 80 MPa. Logging speed is 30 - 60 m/h.

Equipment is operated as component of computerized geophysical station with 3-wire armed cable up to 5,000 m long and with the following surface devices: universal signal recorder (e.g., "Vulkan"), adapted to AINGK-89S equipment, and DC power source like "ÁÏ-303" or "Gekat-300-1".

SHC composition:

• AINGK-89S borehole tool;
• software for logging control and preliminary result processing;
• metrological support including standard spectra library;
• logging and result processing manual.

Main technical features of AINGK-89S hardware:

The borehole tool AINGK-89S is 3,390 mm long.
The tool has an adapter for AGK-89S equipment. The total length of connected AINGK-89S and AGK-89S is 4,900 mm.
The diameter of the armored shell is 89 mm. On the shell near the detection unit there is a cylinder-shaped attachment 600 mm long, 110 mm in diameter.
The borehole tool voltage is 150 - 250 V DC, power consumption is 50 W.
The code of data exchange between the borehole tool and the surface equipment is MANCHESTER-II.
Detector type and dimensions: temperature-controlled BGO 50 x 100 mm
Number of quantization levels for pulse amplitudes: 1024.
Number of measured amplitude spectra: 6.
Number of quantization levels for time intervals: 256.
Number of measured time distributions: 2.
Maximal count rate for spectrometric tract: PNGL-S channel - 2,5·10⁵ pulse/sec.
Store capacity: 2 x 32 kB.
Energy scale drift correction is performed by the software using standard spectra at the data processing stage. Error of the scale is not more than 0.5 channel, which is 5 keV.

Main metrological features of SHC:

Range of macroscopic section of thermal neutron absorption measurement:
Σ_à is 7·10³...30·10³ cm^-1.
Relative error of Σ_à measurement is not more than 3%.
Relative statistical error of determining main mineral rock components is not more than 10%.
Relative differentiation of main interpretational parameter for C/O logging (COR) for oil and water bearing layers:
at porosity 40%.......................30%;
at porosity 20%.......................12%.
Relative statistical error of COR determination for measurement time 3 minutes (3 runs at a 1 meter layer with logging speed 60 m/h) is not more than 1%.
Relative statistical error of saturation determination under 2 component fluid composition (oil and water) in terrigenous collectors (porosity more than 15 %) is not more than 15%, and in carbonate collectors (porosity more than 7 %) is not more than 22%.

	Hardware and software complex with gamma spectrometric equipment AGK-89S

Purpose: Software and hardware complex (SHC) with AGK-89S equipment is designed to investigate boreholes during search, exploring and development of petroleum fields using spectrometric gamma well-logging (GL-S) in order to separate rocks by their lithological types, determine reference horizons, determine clayiness of terrigenous collectors, etc.

Information capabilities: As theresult of data processing the following geologic and geophysical characteristics of layers are obtained:

• natural integral gamma radioactivity;
• natural radioactive elements - U(Ra), Th and K concentrations.

Measurement conditions: Measurements are made in open and cased holes with interior diameter greater than 110 mm at temperature up to +120^îC and a hydrostatic pressure up to 80 MPa. Logging speed is 120 - 400 m/h.

Equipment is operated as component of computerized geophysical station with 3-wire armed cable up to 5,000 m long and universal digital recorder, e.g., "Vulkan".

SHC composition:

• AGK-89S borehole tool;
• software for logging control and preliminary result processing;
• metrological support including standard spectra library;
• logging and result processing manual.

Main technical features of AGK-89S:

Borehole tool length: 1,786 mm.
Borehole tool diameter : 89 mm.
Borehole tool DC voltage: 150 - 250 V, power consumption: 10 W.
Code of data exchange between the borehole tool and surface equipment is MANCHESTER-II.
Detector type and dimensions: CsI(Na), d 50 x 250.
Number of amplitude channels: 1024.
Maximal count rate for spectrometric tract: 2·10⁴ pulse/sec.
Borehole store capacity: 2 õ 32 kB.
Energy scale drift correction is performed by the software using standard spectra at the data processing stage. Error of the scale is not more than 0.2 channel, which is 0.6 keV.

Main metrological features of SHC:

Concentration determination range for natural radioelements:
U(Ra), Th...................................1 - 100 ppm;
K..............................................over 0.3%.
Relative error in determination of natural radioactive elements concentration in terrigenous collectors is not more than 20%.

	Hardware and software complex with gamma spectrometric equipment AINK-89S

Purpose: Software and hardware complex (SHC) with two-module AINK-89S equipment is designed to investigate boreholes during exploration and development control at petroleum fields using spectral gamma well-logging (GL-S), one-module pulsed neutron gamma well-logging (PNGL-S) and carbon-oxygen logging (C/O logging) in order to measure the collector oil-saturation regardless of water mineralization.

Information capabilities: As a result of data processing the following geologic and geophysical characteristics of layers are obtained:

• natural integral gamma radioactivity;
• natural radioactive elements - U (Ra), Th and K concentrations;
• relative concentrations of main mineral components of rock matrix;
• hydrogen index;
• macroscopic capture section or thermal neutron lifetime;
• oil saturation factor;
• gas saturation factor.

Measurement conditions: Measurements are made in cased holes with interior diameter greater than 127 mm against non-perforated layers with temperature up to +120^îC and hydrostatic pressure up to 80 MPa. Logging speed is 30 - 120 m/h.

Equipment is operated as component of computerized geophysical station with 3-wire armed cable up to 5,000 m long and with the following surface devices: universal signal recorder (e.g., "Vulkan") and DC power source like "ÁÏ-303" or "Gekat-300-1".

SHC composition:

• AINK-89S two-module borehole tool;
• software for logging control and preliminary result processing;
• metrological support including standard spectra library;
• logging and result processing manual.

Main technical features of AINK-89S equipment:

Borehole tool consists of two independent modules (GL-S and PNGL-S) connected with an adapter.
GL-S module is 1,640 mm long.
PNGL-S module is 3,390 mm long.
Total length of both modules is 4,900 mm. Diameter of the armored shell of both modules is 89 mm. On the shell of PNGL-S module near the detection unit there is a cylinder-shaped attachment 600 mm long, 110 mm in diameter.
Borehole tool voltage is 150 - 250 V DC, power consumption is 50 W.
Code of data exchange between the borehole tool and surface equipment is MANCHESTER-II.
Detector type and dimensions:
in PNGL-S module......................temperature-controlled BGO, d 50 x 100 mm;
in GL-S module.........................CsI(Na), d 50 x 250 mm.
Number of quantization levels for pulse amplitudes: 1024.
Number of measured amplitude spectra: 6 (PNGL-S) + 1 (GL-S).
Number of quantization levels for time intervals: 256.
Number of measured time distributions: 2.
Maximal count rate for spectrometric tract:
PNGL-S channel.........................2.5·10⁵ pulse/sec;
GL-S channel.............................2·10⁴ pulse/sec.
Store capacity: 2 x 32 kB.
Energy scale drift correction is performed using standard spectra at the data processing stage. Error of the scale is not more than 0.5 channel for PNGL-S and 0.2 channel for GL-S, which is 5 keV in PNGL-S spectra and 0.6 keV in GL-S spectra.

Main metrological features of SHC:

Concentration determination range for natural radioelements:
U(Ra), Th..................................1 - 100 ppm;
K.............................................more than 0.3%.
Relative determination error for natural radioactive elements in terrigenous collectors is not more than 20%.
Range of macroscopic section of thermal neutron absorption measurement - Σ_à is 7·10³...30·10³ cm^-1.
Relative error of Σ_à measurement is not more than 3%.
Relative statistical error of determining main mineral rock components is not more than 10%.
Relative differentiation of main interpretational parameter for C/O logging (COR) for oil and water bearing layers:
at porosity 40%.......................30%;
at porosity 20%.......................12%.
Relative statistical error of COR determination for measurement time 3 minutes (3 runs at a 1 meter layer with logging speed 60 m/h) is not more than 1%.
Relative statistical error of saturation determination under 2 component fluid composition (oil and water) in terrigenous collectors (porosity more than 15 %) is not more than 15%, and in carbonate collectors (porosity more than 7 %) is not more than 22%.

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