Technology - How SlimDrill Works

Where it comes from

Mineral-mining drilling, re-engineered for hydrocarbon wells.

Mineral-mining rigs were our starting point. To make them work for oil & gas, we solved a long list of engineering problems - over multiple field seasons, on real projects.

View the full engineering log - features of mineral mining adapted, and issues solved during pilot studies

Starting point: mineral-mining rig features

Small lift capacity, typically 5-10 tons
Low derrick floor - easy access, but hard to install wellhead equipment
Limited solid-face drilling possibilities
"Toy" sizes everywhere - drill pipe ⌀ 44-70 mm, mud pump rate 1-3 L/s
Water instead of drilling mud
No closed-loop mud circulation
No BOP equipment
No cemented casing - only temporary casing used
Limited logging options
No drilling parameters recording

Solved during pilot studies

Lift capacity - sourced the largest available wireline coring rigs
Low ROP - adopted solid toolface bits and BHAs
Bit lifetime - careful selection of conventional PDC bits, parameters and nozzle sets
High ECP - increased annulus, larger pumps
Pipe breakage - strengthened collarless pipes with internal upset
Narrow production casing - larger intermediate casings, upgraded rod holder
Hole cleaning - polymer-based mud recipes, OBM where needed
Cavernosity in shales - selected effective shale inhibitors, OBM
Open-loop costs - adopted closed-loop mud cleaning systems
Gas/oil safety - outrigger upgrades, BOP pit, conventional & MPD BOP
Logging - sourced and tested slim modular logging strings
Stuck logging tools - modular sets, centralizers, drill-pipe conveyance
Cementing & casing - hydraulic borehole extenders, lightweight cement
Mud logging - adapted standard mud-logging equipment to wireline rigs

Technology

Full oil & gas capability - at slim-hole scale.

Every subsystem you would expect on a conventional rig - drilling, BOP, mud filtration, casing, logging, perforation, fracturing - adapted, tested and validated at slim-hole scale.

A Drilling site & crew

A 40×50 m site. Heavy equipment on 3×6 concrete pads, lighter equipment on tundramats. No site fill required - the rig's low specific ground pressure works directly on compacted summer ground or winter ice.

Crew composition

Mandatory: Toolpusher (1+1), Drillers (1×2 day/night), Roughnecks (3×2), Mud engineer, Mechanic, Electrician
Optional: Specialized vehicle operators, Geologist, Cook (1+1)

B Drill pipes & BHA

Specialized collarless (no IU/EU) pipes for wireline core drilling, ⌀ 70/89/114 mm. Reinforced collarless (IU) pipes for solid-face drilling, ⌀ 89/114 mm - engineered to sustain higher axial, tangential and vibrational loads, increasing solid-face ROP.

Pump rate

1-1.2 L/s

6-8 L/s

WOB

1.5-3 t

3-4 t

RPM

400-500

150-250

C Mud pumps & filtration

SIN46 pump for solid-face drilling (up to 400 L/min, powered from main hydraulic system). FMC coring pumps ×2, up to 120 L/min each. External CSA/CA-320 pumping/cementing units.

Filtration: TriFlo MFS-4000 (US) 2-stage modular, "NEST" (CN) 3-stage modular, Derrick Hyperpool shaker, GN Solids Control centrifuge, Pulsar D504 shaker (RU).

D Casing

Standard API joints (with collars, max length 11 m) work for casing. For narrow-annulus constructions we use collarless casing matching wireline drill-pipe geometry - ⌀ 70/89/114/140/(168) mm, length 6 m, WT thread, 150 bar pressure rating.

Custom non-API collarless threads graded for oil & gas can be ordered for higher pressure rates (minimum batch 150-200 tons).

E BOP equipment

3,000 and 5,000 psi BOP sets with manual and hydraulic control. 2-ram (blind + tube) and inflatable preventers. All equipment satisfies current regulatory requirements in Russia and CIS countries. Advanced BOP (Managed Pressure Drilling) tested and available.

F Wireline coring

Core sizes 48/63/85 mm (NQ/HQ/PQ). Core length per trip 1.5-6 m. Full trip-around at 1,000 m depth: 30-40 minutes. Optional core orientation module and triple-tube assembly for additional core safety and isolation.

100% core recovery, even in cracked and faulted formations
Fast recovery without full drill-string raise - HC saturation visible in real time
Subtle structural features visible (e.g. faults with displacement ≈20 mm)

G Logging - standard & advanced

Modular tool strings on drill pipes or wireline (vendors: AMK-Horizont, KARSAR/Logservice, TPG). Tool diameters: 90 mm (open holes >115 mm, full standard suite), 73 mm (>98 mm, full suite), 60 mm (<98 mm, gamma/neutron/sonic). Tool string length 25-30 m. Cased-hole logging with standard 28/42/76/100 mm tools.

Advanced methods (slim-hole tools)

Schlumberger: NMR (CMR-Plus, 135 mm), Imagers (FMI 127 mm, OBMI, UBI 89 mm), Sonic Scanner 92 mm, ThruBit family 54 mm
Baker Hughes: NMR (MREX 127 mm), Imagers (STAR/STARXD 133 mm), Sonic XMAC 98.6 mm
Weatherford: Most advanced slim-hole set on market - NMR FMRT 127 mm, CMI-Compact 60 mm, Cross-Dipole CXD 57 mm
KARSAR (Logservice): Local Russian producer - NMR 5YaK 127 mm, MS-110/MS-80N imagers, Cross-dipole 8AD 73 mm

H MWD/LWD & directional drilling

State-of-the-art gamma and multi-depth resistivity tools available and tested, alongside standard navigation methods. Successfully tested directional drilling with mud motors and a Russian-developed rotary system.

I Open-hole testing

Tools available for very slim open holes (76-123.8 mm), adapted from coalbed methane (CBM) exploration practice. Multiple build-up and inflow analyses possible per run.

J Perforation, testing, intensification

Perforation: wireline or tubing (60/73 mm), perforator ⌀ 64/73/89 mm, charge 14-21 g
Well start: fluid replacement, swabbing, nitrogen compressor, ejector, wireline ESP
Testing: pressure gauges and samplers in 38-42 mm diameter
Artificial lift: SRP/PCP 3-30 m³/day; ESP slim 2А & 3 - 30-150 m³/day
Frac & acid: standard axial packers 72/80/88 mm. 5 fracs done (89/114 casing, slick-water and xanthan-based fluids), max rate 2 m³/min, max wellhead pressure 350 bar. 3 acid jobs completed.