Multi-conductor cables are used primarily in open- (and cased-) hole functions. Typically they've diameters from 0.377' to 0.548' with instructed working masses from 6.6k to 20k lbf.
(Note that wireline diameters and performance traits are sometimes expressed in imperial units.) Multi-conductor cables could be sheathed in easy polymer coverings however are extra commonly open wound cables. Associated with this, 'wireline logging' is the acquisition and evaluation of geophysical and petrophysical data and the availability of related services provided as a perform of along-gap depth.
The last kind of casing string that's run into the properly, and due to this fact the smallest in diameter, is the production or oil string. A cement slurry is then pumped into the properly and allowed to harden to completely fix the casing in place.
To scale back the amount of time running in the well, several wireline instruments are sometimes joined collectively and run simultaneously in a software string that may be lots of of ft lengthy and weigh more than 5000 lbs. When producing wells require remedial work to sustain, restore or improve production, this is known as workover. Many times, workover operations require production shut-in, however not at all times. Multi-conductor strains include external armor wires wound round a core of sometimes 4- or 7-conductors.
After the cement has hardened, the bottom of the well is drilled out, and the completion process continues. After working the casing and earlier than the cementing the properly, a used drill bit is inserted into the properly via a drillstring, and drilling fluid is then circulated for a certain period of time to remove any remaining cuttings from the properly. Also wall scratchers are dispatched into the nicely to remove any filter cake that will have shaped on the perimeters of the nicely.
The conductors are certain together in a central core, protected by the outer armor wires. These conductors are used to transmit power to the downhole instrumentation and transmit information (and instructions) to and from the surface.
The data from these receivers are logged as traveltimes for the three and five foot receivers and as a micro-seismogram. The NMR measurement made by each a laboratory instrument and a logging device follow the same ideas very closely. An essential function of the NMR measurement is the time needed to accumulate it.
In a log, there is a commerce-off between the time wanted for polarization and acquisition, logging speed and frequency of sampling. The longer the polarization and acquisition, the extra complete the measurement. However, the longer instances require both lower logging velocity or less frequent sampling. Some resistivity tools have many electrodes mounted on a number of articulated pads, permitting for multiple micro-resistivity measurements. These micro-resistivities have a really shallow depth of investigation, typically within the vary of zero.1 to 0.8 inches, making them appropriate for borehole imaging.
Resistivity imagers can be found which operate utilizing induction methods for resistive mud methods (oil base), and direct present strategies for conductive mud techniques (water primarily based). Formation porosity is decided by putting in a radiation source able to emitting fast neutrons into the downhole environment. Any pore spaces in the rock are filled with fluid containing hydrogen atoms, which sluggish the neutrons down to an epithermal or thermal state. This atomic interaction creates gamma rays which are then measured within the tool through dedicated detectors, and interpreted by way of a calibration to a porosity. A higher number of gamma rays collected on the device sensor would indicate a larger number of interactions with hydrogen atoms, and thus a bigger porosity.
Wireline (or electric line) is the commonest method for perforating wells, and is achieved by lowering or pumping the perforating guns down-hole and then initiating the sequence through electric line. This provides simple, quick depth management and selectivity together with lowered safety risks of personnel and equipment. Multiple intervals, which could be extensively separated, may be perforated in a single run.