Ahead-of-Bit Prediction

LookAhead — Ahead-of-Bit Prediction

LookAhead projects the geological model ahead of the current bit position, allowing the geosteering engineer to anticipate formation changes before the drill bit reaches them. It combines the current geological interpretation with the planned well trajectory to produce a forward-looking subsurface picture.

Opening LookAhead

From the project workspace, click the LookAhead tab.

LookAhead requires:

• An active geological model with at least one formation defined

• A well trajectory (planned or actual, or both)

How LookAhead Works

LookAhead uses three inputs to generate its prediction:

1. Current geological model — formation tops, dips, and layer geometry as currently interpreted

2. Planned trajectory — the target well path ahead of the bit

3. Offset well data (optional but recommended) — formation tops from nearby wells that constrain the subsurface model

From these inputs, GeoMaster calculates:

• Predicted depth of each formation top as the well will penetrate it

• Predicted TST/TVT within each formation

• Uncertainty envelope around each prediction (based on dip uncertainty and model confidence)

Reading the LookAhead View

The LookAhead display shows a forward-looking cross-section extending from the current bit position to the configured look-ahead distance.

    Current bit ──►  [Look-ahead zone]

    ════════════════════════════════════════
         Shale                            ← Formation boundary (predicted)
    ────────────────────────────────────────  ← Uncertainty envelope (upper)
         Reservoir Sand       ◄── Target zone
    ────────────────────────────────────────  ← Uncertainty envelope (lower)
         Tight / Carbonate
    ════════════════════════════════════════

                    ↑
              Planned trajectory

Prediction Panel (Right Sidebar)

Configuring LookAhead Distance

The look-ahead range controls how far ahead of the bit the prediction extends.

1. Go to Project Settings → Default LookAhead Range

2. Set the distance in metres or feet (MD)

3. Click Save

Typical values:

• 100–200 m MD: Short-range, high confidence — useful when near a critical formation boundary

• 300–500 m MD: Standard operational range

• 500–1000 m MD: Long-range planning — confidence decreases with distance

Updating the Prediction

The LookAhead prediction updates automatically when:

• New survey stations are received (actual trajectory advances)

• Formation tops are re-picked in the Geosteering workspace

• The geological model is edited

To manually force a recalculation, click Refresh in the top-right of the LookAhead tab.

Using Offset Wells to Improve Predictions

Offset wells provide hard data points that constrain the geological model. When LookAhead has access to offset well formation tops:

• Formation boundaries are better constrained laterally

• Uncertainty envelopes narrow around offset well locations

• Structural trends (dip, fault positions) can be incorporated

Adding Offset Wells

1. Go to Data → Offset Wells → Add Offset Well

2. Upload the offset well survey and formation tops (CSV or LAS)

3. GeoMaster will register the offset well and use it in subsequent LookAhead calculations

Uncertainty and Model Confidence

Every LookAhead prediction carries an uncertainty estimate. The confidence score reflects:

Industry Note: LookAhead predictions are model-dependent. A geological model that has not been updated to reflect the most recent log data will produce predictions based on outdated assumptions. Keep your formation top picks and dip estimates current as the well is drilled.

Exporting LookAhead Data

1. Click Export in the top-right of the LookAhead tab

2. Choose:

• LookAhead Report (PDF) — formatted prediction summary with cross-section image

• Formation Top Predictions (CSV) — predicted depths with uncertainty ranges

1. Click Download

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