Devices and outfit for coring

Telescopic core tubes were designed specifically for coring in highly fractured rocks. Their feature is the presence of two sliding internal pipes. The use of telescopic core tubes makes it possible to eliminate two core jams per run and, accordingly, reduce the number of round-trip operations by 2 per each run.

Advantages

• Increased core recovery.
• Increased meterage per 1 run.
• Reduce the number of round-trip operations by 2 per each run.
• Coring with isolating fluid

In order to receive more information about the reservoir, such as grains, change in permeability depending on the azimuth is used oriented core – core recovery with its spatial orientation.

In order to receive more information about the reservoir, such as grains, change in permeability depending on the azimuth is used oriented core – core recovery with its spatial orientation.

Result: better and exact information on reservoir properties spatial distribution.

Protecting core from the negative impact of drilling mud on the initial properties of the material is one of the most important tasks in the design and selection of equipment for coring.

Special design of the core bit and the core catchers shoe minimizes the contact time and the degree of influence of the drilling fluid on the core.

• Special configuration core bit (tangent nozzles, junk slot shape)
• Elongated shoe part with groove seal preventing mud passage
• Isolating agent “IZOKOR” envelopes core surface

Result: core protection from mud, properties retention, more qualitative and representative core for analysis.

Using a core jam detector* (RZK) a patented development that allows real-time identification of the destruction and wedging of a core in a core tube or a set of core catchers makes it possible to significantly increase core recovery in loose, alternating and clastic rocks where it is impossible to determine jamming by ROP reduction or pressure loss. During the core jamming the flushing ports in the RZK overlap and the pressure on the manifold manometer increases sharply, after which you can take a set of measures to eliminate the core jamming and continue further drilling.

Coring into the isolating fluid makes it possible to obtain a large array of additional data on the reservoir. However, when coring in wellbores with a complex profile that reveal unstable interlayers where there is a constant formation of sludge pads and rock debris, there is a great risk of sludge getting into the core tube and squeezing the isolating fluid during trip in hole of the assembly. This system will prevent the above complications.

Advantages

• Protection of core receiver from mudding up during RIH during coring with isolating fluid.
• Protection of core from drilling mud while drilling.
• Uniform core enveloping with isolating agent.
• Protection against cuttings and drilling mud penetration into core receiver during reaming (in complicated wellbores).

Fiberglass core tubes

Specially designed single-use core tubes have low friction coefficient of the inner surface, which reduces the likelihood of core jamming. After POOH they are sawn into meter sections, closed with plugs and placed in boxes for transportation.

Aluminum core tubes

Aluminum core tubes of special design for coring in rocks of any category of coring difficulty. Have low friction coefficient of the inner surface. Used when working in cross-sections with abnormally high temperatures.

Jamming in core tube during coring in fractured rocks is a major cause of premature drilling interruption. The increase in the number of round-trip operations due to core jams can lead to a significant increase in well construction time. Using anti-jamming systems to eliminate 1 jam can effectively solve this problem.

Advantages

• The elimination of one core jam.
• Reduction of well construction time by reducing the number of round-trip operations.

A careless attitude to the lifted core after extraction to the surface can bring all efforts to achieve a quality result to nothing.

During the extraction of tubes with core from the barrel and its lowering onto the catwalks for further segmentation, integrity damage and the formation of man-made cracks are possible. To ensure the safety and integrity of the core, it is necessary to use a special load frame that prevents tubes bending.

During coring in gas-containing rocks, when pulling out of hole, gas can be released into the core tube, which can lead to the destruction of the core during its extraction. Use of accessories and valve.

For outgassing while POOH:

• Set-in valves
• Core tube valve

For outgassing when core extraction:

• Gas relief unit
• Device for safe core tube sections disassembly when coring gas saturated core.

Designed to scan recovered core along the length in rig conditions and determine the total gamma activity to bind the core to the gamma log.

• Allows determining the location of sampling for the conservation of core.
• Operating temperature range from -30 to +60°С.

Advantages:

• Operated from 220 mains and standalone.
• Water and shockproof housing.
• Bluetooth and 3G communication.

Core stabilization

After removing core tube from the barrel in order to preserve the integrity and information capacity of the core it is necessary to take measures to stabilize it.

Today the most effective ways are:

• Core paraffining
• Fast-curing polyurethane foam
• Freezing
• Plastic busing

Core UV photography

The introduction of tracer agents in the drilling mud with further photographing of the ends in ultraviolet light allows estimating the zone of mud filtrate penetration.

During transportation and storage tubes with core can experience negative stress loads, which can lead to core destruction. To preserve the integrity and original quality of the rock it is necessary to use special shipping containers equipped with vibration damping inserts. Also such containers can be used to freeze the core and maintain the required negative temperature during storage and transportation.