A directional driller hands over the definitive survey at the end of each bit run, as WITSML, and the well engineer loads it to run anti-collision checks against the wells already drilled from the same platform template. Three wells over two days, 120 survey stations. WITSML is XML, and DeltaForge reads it through the XML engine under a curated profile rather than a parser of its own: the profile knows that //well is the row and //trajectoryStation explodes, so nobody writes an XPath, and detection is on the document's namespace and elements rather than its extension because these dialects all ship as plain .xml. The flattened columns are the document's full element paths, so a measured depth arrives as wells_well_trajectory_trajectory_station_md; renaming those is most of what the curated Delta layer is for. The trajectories are computed with minimum curvature, so the depths and offsets are internally consistent rather than decorative, and the demo checks it: TVD never exceeds MD, and where inclination is zero the two are equal. The payoff is a real anti-collision scan. Two wells from the same slot pattern come within 3 m of each other at 550 m TVD, just below the template, which is where wells on a template are always closest and always most at risk.
-- ============================================================================
-- Drilling Survey Anti-Collision - Setup Script
-- ============================================================================
-- A directional driller hands over the definitive survey at the end of each
-- bit run, as WITSML. The well engineer needs those trajectories in the lake
-- for two reasons: to tie each well to the geological model, and to run
-- anti-collision checks against the wells already drilled from the same
-- platform template.
--
-- 11 March 15/9-F-11 (40 stations), 15/9-F-11 A (32 stations)
-- 12 March 15/9-F-12 (48 stations)
--
-- All three are drilled from one template, so they leave surface a few metres
-- apart and diverge with depth. That is the whole reason anti-collision
-- exists: the wells are closest where they leave the template, not where they
-- land.
--
-- 1. survey_documents external, DISCOVER over the landing folder
-- 2. survey_stations DELTA, one row per station with usable column names
-- ============================================================================
-- ----------------------------------------------------------------------------
-- STEP 1: Zone and schema
-- ----------------------------------------------------------------------------
CREATE ZONE IF NOT EXISTS {{zone_name}} TYPE EXTERNAL
COMMENT 'External tables - demo datasets and file-backed data';
CREATE SCHEMA IF NOT EXISTS {{zone_name}}.drilling
COMMENT 'WITSML definitive surveys read in place, curated into Delta';
-- ----------------------------------------------------------------------------
-- STEP 2: Register the landing folder with DISCOVER
-- ----------------------------------------------------------------------------
-- WITSML is XML, and DeltaForge reads it through the XML engine under a
-- curated profile rather than a parser of its own. That is the point of the
-- USING keyword here: the profile already knows that `//well` is the row and
-- that `//trajectoryStation` explodes, so nobody writes an XPath.
--
-- Detection is on the document's own vocabulary rather than the extension,
-- because every one of these dialects ships as a plain .xml file and the
-- extension says nothing. A document that merely MENTIONS witsml is not a
-- WITSML document; the namespace or a real element is what counts.
-- ----------------------------------------------------------------------------
DROP EXTERNAL TABLE IF EXISTS {{zone_name}}.drilling.survey_documents;
DISCOVER {{zone_name}}.drilling.survey_documents
PATH '{{data_subdir}}/landing'
WITH (FILE_METADATA = true);
-- ----------------------------------------------------------------------------
-- STEP 3: The curated Delta table
-- ----------------------------------------------------------------------------
-- The flattened column names are the document's full element path, so a
-- station's measured depth arrives as
-- `wells_well_trajectory_trajectory_station_md`. That is correct and
-- unambiguous, and nobody wants to write it twice.
--
-- Renaming them is most of what this curated layer is for. The other part is
-- types: the survey numbers arrive as the document wrote them, and an
-- anti-collision calculation needs doubles it can take a square root of.
-- ----------------------------------------------------------------------------
CREATE DELTA TABLE IF NOT EXISTS {{zone_name}}.drilling.survey_stations (
well VARCHAR,
well_uid VARCHAR,
field VARCHAR,
delivered_on VARCHAR,
source_file VARCHAR,
station_uid VARCHAR,
md_m DOUBLE,
tvd_m DOUBLE,
inclination_deg DOUBLE,
azimuth_deg DOUBLE,
north_m DOUBLE,
east_m DOUBLE
) LOCATION '{{data_subdir}}/curated/survey_stations';## What this demo does A directional driller hands over the definitive survey at the end of each bit run, as WITSML, and the well engineer loads it to run anti-collision checks against the wells already drilled from the same platform template. Three wells over two days, 120 survey stations. WITSML is XML, and DeltaForge reads it through the XML engine under a curated profile rather than a parser of its own: the profile knows that //well is the row and //trajectoryStation explodes, so nobody writes an XPath, and detection is on the document's namespace and elements rather than its extension because these dialects all ship as plain .xml. The flattened columns are the document's full element paths, so a measured depth arrives as wells_well_trajectory_trajectory_station_md; renaming those is most of what the curated Delta layer is for. The trajectories are computed with minimum curvature, so the depths and offsets are internally consistent rather than decorative, and the demo checks it: TVD never exceeds MD, and where inclination is zero the two are equal. The payoff is a real anti-collision scan. Two wells from the same slot pattern come within 3 m of each other at 550 m TVD, just below the template, which is where wells on a template are always closest and always most at risk. ## Formats it reads The setup script registers external tables with: `USING KEYWORD`. ## What it creates - `{{zone_name}}.drilling.survey_documents` (external table) - `{{zone_name}}.drilling.survey_stations` (delta table) ## Running it The demo ships `setup.sql`, `queries.sql` and `cleanup.sql` under `demos/subsurface/witsml-drilling-operations`. The queries carry their own `ASSERT`s, so a run that completes has verified its own numbers. Data: 3 files, 0.0 MB.