6. 1. 1 ground hardware and software system
The main body of the ground system is computer logging LAN, and the system software adopts multi-user operating system, which is highly open. At present, the more advanced ground systems abroad are MAXIS-500 from Schlumberger, eclipse-5700 from Atlas and EXCELL-2000 from Halliburton (Table 6. 1. 1). On 1998, domestic Xi' an Petroleum Exploration Instrument Factory began to develop ERA2000 imaging logging ground system, which has been popularized and applied.
Table 6. 1. 1 imaging logging system
sequential
6. 1.2 data high-speed cable remote transmission system
The data high-speed cable remote transmission system includes transmission and interface. The function of the transmission part is to complete the computer's issuing of control commands for downhole instruments and upload the data collected by downhole instruments to the ground computer. The transmission rate of issuing commands is as high as 40kb/s, and the transmission rate of uploading data is as high as 500 KB/s; The interface part considers compatibility, which can be compatible with the cable remote transmission mode of CNC logging system and solve the data format problem at the same time.
6. 1.3 downhole instrument system
According to the different measured physical quantities, the imaging logging downhole instrument system can be roughly divided into three types: electrical, acoustic and nuclear.
6. 1.3. 1 electrical imaging logging technology
1) formation micro-resistivity imaging logging tool. The representative instruments are FMS and FMI from Schlumberger, STARImager from Atlas and EMI from halliburton. The instrument is equipped with several button electrodes (also called array electrodes) with small spacing on the polar plates 2, 4, 6 and 8, respectively, which can be used for scanning imaging logging of formation micro-resistivity on the borehole wall. With the increase of the number of polar plates, the coverage of array electrodes to the strata around the borehole wall is also increasing, even covering almost the whole borehole. The vertical resolution of the instrument is extremely high, which can be divided into ultra-thin layers with a thickness of 0.2in(5mm), and the radial detection depth is 1 ~ 2 in (2.5 ~ 5 cm). The obtained imaging logging image is as clear and intuitive as the actual core photo.
Formation micro-resistivity imaging logging images can be used to determine formation dip and azimuth; Identify thin layers; Describe the structure and characteristics of oil and gas reservoirs, such as indicating the occurrence and orientation of holes and fractures in oil and gas reservoirs, and selecting horizons that can obtain high oil and gas production for perforation and fracturing; Accurately determine the effective thickness of oil and gas reservoirs (especially ultra-thin sandstone reservoirs); Study erosion surface, fossil layer, fault location and sedimentary environment.
2) Array induction imaging logging tools, represented by AIT of Schlumberger Company and DPIL of Atlas Company. Take AIT as an example, it has a transmitting coil and eight receiving coil pairs, which is equivalent to a three-coil system with eight coil pitches. Working frequencies of 20kHz and 40kHz Z2 are used. Usually, eight groups of coils use the same frequency (20kHz), and six of them use another higher frequency (40kHz) at the same time. In fact, these eight coil systems have 14 detection depths. In addition, the instrument uses software focusing to process the measured signals, and can obtain signals with three longitudinal resolutions of 1ft(30.5cm), 2ft(6 1cm) and 4ft( 122cm). At the same time, each longitudinal resolution can get five radial detection depths [10in (25.4cm), 20in(50.8cm), 30in(76.2cm), 60in ([ 10in(25.4cm), 90in (228.6cm)].
Array induction resistivity imaging logging directly reflects the changes of oil and gas saturation in flushed zone, transition zone and undisturbed formation, and can indicate oil and gas layers, and clearly show bedding, oil and gas content, invasion properties and their characteristics. Array induction imaging logging tool is actually a kind of transverse induction logging tool, which can determine flushed zone resistivity and undisturbed formation resistivity more accurately. In heterogeneous layers, these two kinds of resistivity have a good match, so array induction resistivity logging can also accurately identify oil and gas layers.
3) Azimuth resistivity imaging logging tool. 12 electrode arrays with different orientations are installed in the middle of the shielding electrode A2 of the dual laterolog tool, and the outward opening angle of each electrode is 30, covering the stratum within 360 around the well. These electrodes are combined with dual laterolog to form an azimuth resistivity imaging logging tool, which can measure the deep formation resistivity around the borehole 12 direction. This resistivity reflects the path of power supply current, that is, the resistivity of the medium within the control range of electrode opening angle of 30, which is approximately three-dimensional logging. Therefore, these 12 resistivities will change when the medium around the well is uneven or fractured. In addition, the power supply currents of these 12 azimuth electrodes can be added to obtain high-resolution lateral measurement (LLHR). At the same time, the instrument also retains deep and shallow lateral measurements. The longitudinal resolution of the instrument is 6 ~ 8 inches (15.2 ~ 20.3 cm) and the detection depth is 30 inches (76.2 cm). The resolution of azimuth resistivity imaging logging tool is higher than that of dual laterolog tool, and the image of resistivity change around borehole can be obtained. Compared with formation micro-resistivity scanning imaging logging tool, although its longitudinal resolution is slightly lower, it has two advantages: large detection depth and combined logging with dual laterolog tool.
Azimuth resistivity imaging logging can be used to identify heterogeneous layers; Identify the thin layer and accurately determine the resistivity of the thin layer; Identify cracks and evaluate the effectiveness of natural cracks.
6. 1.3.2 Acoustic imaging logging technology
1) Downhole Acoustic Television (BHTV). Downhole acoustic TV is the earliest developed imaging logging technology, which records the pulse echo signal vertically incident from the sound source to the borehole wall, and produces amplitude imaging and propagation time imaging of borehole wall echo. In open-hole wells, it can intuitively find holes and fractures in oil and gas reservoirs; In cased wells, it can visually check perforation and casing corrosion and fracture.
2) Ultrasonic imaging logging tool. Ultrasonic imaging logging tool provides high-resolution acoustic impedance azimuth imaging logging of casing diameter, thickness, corrosion and cement cementation, which can detect the cementing quality of the first interface and the second interface of oil and gas wells, accurately identify fractures in cementing cement, evaluate the corrosion degree of casing and find natural gas reservoirs. Ultrasonic imaging logging tool and downhole acoustic TV all work according to the principle of pulse echo method.
3) Dipole shear wave imaging logging tool. Dipole shear wave imaging logging tool uses directional dipole sound source, which can receive shear waves in both hard and soft formations. Therefore, the instrument can simultaneously detect P-wave, S-wave and stoneley wave in any formation, and can be used to determine formation lithology, porosity, Poisson's ratio, rock hardness, formation fracture pressure, and identify fractures and gas layers. Its P-wave and S-wave logging data are also widely used in seismic data interpretation.
6. 1.3.3 nuclear imaging logging technology
1) array nuclear imaging logging tool. Array nuclear imaging logging tool is also called nuclear porosity lithology imaging sidetracking tool. The instrument uses neutron generator instead of chemical neutron source, uses multi-probe to detect overheated neutron porosity, neutron slow-time porosity, high-resolution neutron porosity and thermal neutron capture cross section of formation (measured at the same time as neutron porosity), and uses bismuth germanate detector to detect gamma source multi-channel energy spectrum formation density, Shuang Yuan distance photoelectric absorption index and passive dual-probe natural gamma energy spectrum (uranium, thorium and potassium content) to form porosity lithologic imaging logging map, which is used to determine rock resistivity and background values of rock minerals in oil and gas reservoirs.
2) Carbon-oxygen specific energy spectrum imaging logging tool. Through-tubing dual-probe carbon-oxygen specific energy spectrum imaging logging tool can monitor the change of oil and gas saturation outside casing, and can be used in conjunction with small production logging tools to provide imaging logging monitoring images for rational oil field exploitation.
3) Geochemical imaging logging tool. Geochemical imaging logging tool consists of natural gamma-ray spectrum logging tool, secondary gamma-ray spectrum logging tool, aluminum activated clay logging tool and thermal neutron or superheated neutron logging tool. Geochemical imaging logging tool based on nuclear energy spectrum can detect more complex rock mineral components and identify the mineral types and abundance of strata. Its main purpose is to determine the clay content, cation exchange capacity, particle size, porosity, permeability, saturation and sedimentary environment of oil and gas reservoirs.
4) Magnetic resonance imaging logging tool. Under the guidance of the basic idea of magnetic resonance imaging, the magnetic resonance imaging logging tool is successfully developed by using the principle of interaction between nuclear magnetic moment and external magnetic field. It can detect formation parameters such as porosity, permeability and irreducible water saturation at the same time, which is recognized by foreign oil circles as the most significant progress of logging technology in recent ten years.
6. 1.3.4 image interpretation system
Imaging logging data processing and interpretation system, including on-site rapid processing and interpretation system and image interpretation workstation.
The hardware of imaging logging data processing and interpretation system is computer local area network, and the typical workstation software mainly includes system core, system service and interpretation application.
The core of the system includes man-machine interface and data display interface, data management, application management, database and data file functions. Man-machine interface and data display interface solve the communication dialogue between users and computers and the connection between computers and output devices. Data management involves the design and implementation of what data to store, data format and structure, access address and access mode. Application management includes calling application modules and selecting interpretation parameters.
System services are various data processing services, including data loading and unloading, data transmission, playback, making hard copies and printing reports.
Interpretation application is to complete the interpretation, contrast synthesis, display and inspection of image data. Interpretation and application need to establish a series of packages, such as petrophysics package, geological package, geophysical package, reservoir engineering package, development engineering package, data processing package and so on.