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Deep Sink Technologies Ltd

Service 01 · Headline service

Borehole Logging & Interpretation

Wireline logging, petrophysics and core-log integration that turn a borehole into a calibrated record of the formations it crosses.

Request a proposal What you receive

01 / The problem

A borehole is the only place where the subsurface is measured directly, and it is expensive to drill. Driller's descriptions and cuttings alone leave the depth, thickness and properties of each formation uncertain. Logging records those properties continuously against depth, and interpretation turns the curves into quantities a project can use: lithology, porosity, fluid content, fracturing and temperature.

02 / Approach

How the work is done.

  1. Plan the programme

    The questions the well has to answer decide the logging suite, the order of runs and the depth control. Hole diameter, fluid and casing are checked against tool limits before mobilization.

  2. Acquire

    Wireline runs are recorded with calibration checks before and after, and a repeat section on each run to show the measurement is reproducible.

  3. Quality-control and correct

    Runs are depth-matched to a reference log, corrected for borehole size and fluid, and flagged where hole condition makes a reading unreliable.

  4. Integrate with core and tests

    Where core, cuttings or pumping and injection tests exist, the logs are tied to them so that the interpretation is calibrated rather than assumed.

  5. Interpret

    A petrophysical model converts the curves to lithology, clay volume, porosity and fluid indicators, with the parameter choices and their uncertainty recorded.

  6. Report and hand over

    Composite logs, interpreted curves, the QC record and the report are delivered together, in formats the client can reuse.

03 / Logging suites and what each measures

Logging suites and what each measures

No single log identifies a rock or its fluids. A suite is chosen so that each curve constrains the others.

Common wireline logs
Log What it measures Typical unit Used for
Caliper Borehole diameter mm Hole condition, washouts, and corrections to the other logs
Natural gamma ray (GR) Natural radioactivity of the formation gAPI Lithology and clay content, correlation between wells, depth matching
Spectral gamma ray Separate potassium, uranium and thorium contributions %, ppm Clay typing; telling radioactive non-clay rocks from claystone
Resistivity, deep and shallow Electrical resistivity at two or more depths of investigation ohm·m Fluid type and salinity, porosity, and how far drilling fluid has invaded
Spontaneous potential (SP) Natural electrical potential in the borehole mV Permeable beds and formation-water resistivity
Bulk density Electron density, converted to bulk density g/cm³ Porosity and lithology
Neutron porosity Hydrogen content of the formation v/v Porosity; with density, clay and gas effects
Sonic Travel time of compressional and shear waves µs/m Porosity, mechanical properties, and the tie to seismic data
Borehole imaging Oriented acoustic or optical image of the borehole wall image Fractures, bedding, vesicular zones and borehole breakout
Temperature and fluid conductivity Temperature and electrical conductivity of the borehole fluid °C, µS/cm Inflow zones, water quality changes and geothermal gradient
Flowmeter Vertical flow in the borehole L/min Which intervals actually produce or take fluid

Source: General logging practice. The tools DeepSink runs or subcontracts are to be confirmed [VERIFY: tool inventory].

04 / Core-log integration

Core-log integration

Core gives direct laboratory measurements on a few metres of rock; logs give indirect measurements over the whole well. Joining them is what makes an interpretation defensible.

  1. Depth matching

    A core gamma scan is matched to the log gamma-ray curve and the shifts are recorded interval by interval.

  2. Calibration

    Log-derived porosity and grain density are compared with plug measurements at matched depths, allowing for the difference in sample volume.

  3. Rock typing

    Core descriptions define the rock types, and the log response of each is used to recognize them in uncored intervals.

  4. Extension

    The calibrated model is applied to the rest of the well and to neighbouring wells that have logs but no core.

05 / QC and data-standards practice

QC and data-standards practice

A log is evidence only if someone else can check how it was acquired and processed. [VERIFY: written QC procedure]

  1. Calibration records before and after each run, kept with the data.
  2. A repeat section on every run, and a comparison of main and repeat passes.
  3. Depth control against a single reference log, tied to a fixed datum such as the casing shoe.
  4. Environmental corrections for hole size and fluid, each one documented.

  5. Complete log headers

    Location, datum, hole and fluid details, tool serial numbers and run times.
  6. Delivery in open, standard log formats with raw and corrected curves kept separate [VERIFY: formats, for example LAS or DLIS].
  7. A parameter audit trail, so that the interpretation can be repeated.

06 / Deliverables

What you receive.

Each engagement ends with documents and data that can be filed, checked and reused.

  • Field prints and digital logs, raw and corrected
  • A composite log with lithology column and formation tops
  • Petrophysical interpretation: clay volume, porosity and fluid indicators, with uncertainty
  • A core-log integration report where core exists
  • Fracture and structural picks from image logs, where run
  • The QC record: calibrations, repeat sections and corrections applied
  • All data in open formats for reuse [VERIFY: formats]

07 / Tools and data

Tools, software and data used
Category What is used
Wireline logging tools Caliper, gamma ray, resistivity, density, neutron, sonic, imaging, temperature, conductivity and flowmeter sondes [VERIFY: owned or subcontracted]
Core measurements Core gamma scanning and routine plug analysis through laboratory partners [VERIFY: laboratories used]
Interpretation software Petrophysical interpretation and log-plotting software [VERIFY: packages used]
Data Client well files, driller logs, core and cuttings descriptions, pumping or injection tests, and offset wells

Source: Tool types and software categories only. Named products are added once confirmed by the owner.

08 / Sample figure

What the evidence looks like.

An illustrative figure built from synthetic data, to show the form of the output. It is not from a client project.
Fig. 1 Illustrative well-log panel. Gamma ray, deep and shallow resistivity (log scale), bulk density with neutron porosity, and sonic against one depth axis. The shaded band marks a vesicular basalt interval that separates from the massive flows on every track. Source: Synthetic data generated for illustration; not a client well.

09 / Related case study

In practice.

Case studies are published only with the client's agreement. Entries marked as placeholders show the structure, not a real project [VERIFY].

All projects
Groundwater

Placeholder case study

Groundwater borehole logging programme [VERIFY]

Placeholder case study. Wireline logging and interpretation across a set of groundwater boreholes to map aquifer intervals and support a monitoring network design.

10 / Questions

Common questions.

Can existing or cased boreholes be logged?

Often, yes. Gamma ray, neutron and temperature logs work through casing. Resistivity, density and imaging generally need an open hole, or respond differently through plastic casing than through steel. A review of the well file shows what is achievable before anything is mobilized.

What hole diameters and depths can be logged?

This depends on the tools and winch used [VERIFY: diameter range, depth and temperature ratings].

Do you run the tools yourselves?

Acquisition is carried out by DeepSink or by a logging contractor under our supervision, depending on the suite and location [VERIFY: which]. Interpretation is done in-house in either case.

What do you need from the driller?

Hole diameter and depth, casing details, the drilling fluid used, any known problem zones, and enough time on the hole for the planned runs.

How long does it take?

Acquisition is typically a matter of hours to a few days per well; interpretation and reporting follow [VERIFY: typical turnaround].

11 / Other services

02

Carbon Storage & Climate

Screening, monitoring design and technical evaluation for CO2 storage, stated with the uncertainty a regulator or investor needs to see.

03

Subsurface Resources

Resource evaluation for groundwater, basalt and geothermal wells, built on logged and tested data rather than surface inference alone.

05

Training & Curriculum Development

Courses and curricula in borehole logging, interpretation and carbon storage, built so that agency, industry and university teams can do the work themselves.

12 / Request a proposal

Discuss borehole logging & interpretation.

Tell us the decision the work has to support, the site or data you have, and any deadline.

The decision the work supports, the site or data you have, and any deadline.

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