OilAuthority.com

Horizontal Drilling: Definition, Process, and Global Applications

What Is Horizontal Drilling?

Horizontal drilling deflects a wellbore from vertical to a near-horizontal trajectory inside the target formation, exposing thousands of meters of reservoir rock to the production string. Operators use horizontal wells to develop tight oil, shale gas, and thin-pay conventional reservoirs across the Permian Basin, the Montney, the Duvernay, Australia's Cooper Basin, and the Middle East carbonates of Ghawar and Rumaila.

Key Takeaways

  • Horizontal drilling is the industry-standard technique for developing unconventional shale, tight oil, and tight gas plays, with laterals routinely exceeding 3,000 m (9,843 ft) in the Permian, Montney, and Duvernay.
  • Steerable rotary systems guide the bit using MWD and LWD tools, holding the wellbore inside a reservoir interval as thin as 3 m (10 ft) over lateral lengths of several kilometers.
  • Operators, completions engineers, and investors track lateral length because longer laterals materially increase estimated ultimate recovery (EUR) and break-even economics in shale plays.
  • Regulatory frameworks span AER Directive 083 for fracturing in Alberta, Texas Railroad Commission Rule 38 for spacing in the Permian, NOPSEMA for offshore horizontals in the Carnarvon Basin, and Sodir for extended-reach wells on the Norwegian Continental Shelf.
  • Canada's longest onshore well, drilled by Veren Inc. in the Duvernay in 2024, reached a total measured depth of 9,017 m (29,583 ft) with a 5,432 m (17,822 ft) lateral.

How Horizontal Drilling Works

A horizontal well begins as a conventional vertical hole. The drilling crew runs surface casing and intermediate casing to isolate shallow formations, then kicks off the build section at a predetermined depth called the kickoff point (KOP). From the KOP, directional tools steer the bit through a build curve, typically 8 to 12 degrees of inclination per 30 m (100 ft), until the wellbore reaches 85 to 95 degrees from vertical. The driller then lands the well inside the target reservoir and drills the horizontal lateral, also called the production leg, along the target interval.

Steering uses a combination of a positive displacement motor (PDM) with a bent housing or a rotary steerable system (RSS). PDMs flex the bottomhole assembly slightly off-axis to generate side force, while RSS tools apply side force at the bit through servo-actuated pads or an offset internal shaft, allowing continuous rotation of the entire drill string. Modern RSS tools from Schlumberger, Halliburton, and Baker Hughes hold the well trajectory within 0.5 m (1.6 ft) of the planned path over laterals of 3,000 to 5,000 m (9,843 to 16,404 ft), reading formation properties in real time through gamma ray, resistivity, and sonic LWD sensors.

Once the lateral is drilled, crews run production casing or a liner and cement it in place using cement blends tailored to the thermal and pressure environment. Multi-stage hydraulic fracturing then stimulates the reservoir through 30 to 60 individual fracture stages spaced 50 to 100 m (164 to 328 ft) apart along the lateral, creating a network of conductive fractures that connects the wellbore to the surrounding rock.

Horizontal Drilling Across International Jurisdictions

Horizontal drilling dominates North American unconventional development. In Canada, AER Directive 083 governs subsurface integrity for hydraulically fractured horizontal wells in Alberta, covering the Montney, Duvernay, Cardium, and oil sands non-thermal plays. Directive 017 covers measurement, and the broader OGCA licensing regime requires horizontal well trajectories to be surveyed and filed with the AER before production commences. BC Energy Regulator enforces matching standards across the BC Montney, which accounts for approximately 40% of Canadian horizontal rig activity in 2026.

In the United States, the Texas Railroad Commission regulates horizontal wells across the Permian Basin and Eagle Ford through field-specific spacing rules and Statewide Rule 38, while the North Dakota Industrial Commission governs the Bakken. The EPA regulates methane emissions from horizontal wells under the 2024 Final Rule for Oil and Natural Gas Sector Emissions, now in full implementation across 2026 operations. Offshore, BSEE 30 CFR 250 applies to horizontal wells drilled from deepwater templates in the Gulf of Mexico Wilcox play, where Chevron's Anchor and Shell's Whale projects employ extended-reach horizontal sections.

Australia's NOPSEMA regulates horizontal wells drilled offshore in the Carnarvon and Browse basins, while state regulators cover onshore horizontals in the Cooper Basin (South Australia), the Bowen and Surat basins (Queensland), and the Beetaloo (Northern Territory). Norway's Sodir oversees horizontal and extended-reach wells across the Norwegian Continental Shelf, including Troll, Snøhvit, Ekofisk, and the pre-salt Johan Sverdrup complex. The Middle East uses horizontal drilling extensively in the Ghawar (Saudi Aramco), Rumaila (BP/PetroChina), Manifa (Saudi Aramco), and the offshore Upper Zakum and Lower Zakum (ADNOC), with multilateral horizontal configurations common in carbonate reservoirs.

Fast Facts

ExxonMobil's Sakhalin-1 Chayvo Z-42 well, drilled in 2013 from onshore Russia, reached a total measured depth of 12,700 m (41,667 ft) with a horizontal departure of 11,739 m (38,514 ft), one of the longest extended-reach wells ever drilled. ExxonMobil has since drilled nine of the ten longest step-out ERD wells from Sakhalin Island, demonstrating the commercial viability of horizontal drilling from onshore pads to reach offshore reservoirs without installing seabed infrastructure.

Lateral Length and Well Design

Operators have lengthened laterals steadily over the last decade in pursuit of better per-well economics. In 2012, the average Permian horizontal lateral ran 1,800 m (5,906 ft). By 2025, the industry average surpassed 3,350 m (10,991 ft), and operators such as Chevron, ExxonMobil, and Pioneer Natural Resources routinely drill 4,500 m (14,764 ft) laterals in the Delaware Basin. The Montney and Duvernay have followed a similar trajectory: Veren Inc.'s 5,432 m (17,822 ft) lateral in the Duvernay, announced in May 2024, became Canada's longest onshore lateral and demonstrated the technical headroom for further extension.

Lateral length materially improves project economics by dividing the fixed cost of the vertical section and the surface pad across more producing reservoir rock. A 4,500 m (14,764 ft) lateral in the Permian Midland typically produces 40% to 60% more cumulative oil than a 3,000 m (9,843 ft) lateral at roughly 25% higher drilling cost, driving internal rate of return improvements of 5 to 10 percentage points on comparable acreage. Investors and analysts at Goldman Sachs, RBC Capital Markets, and Wood Mackenzie publish quarterly benchmarks on lateral length as one of the cleanest indicators of operational efficiency by operator and basin.

Tip: Longer laterals are not universally better. Proppant and fluid placement becomes less efficient beyond roughly 4,500 m (14,764 ft), and individual fracture stage effectiveness declines as frictional pressure losses and near-wellbore complexity increase. Operators in the Montney and Delaware have begun reporting incremental EUR per foot declining above 15,000 ft (4,572 m), suggesting an economic plateau absent further completion innovation.

  • Directional drilling: the broader category of non-vertical drilling; horizontal drilling is the subset at 80 to 95 degrees inclination.
  • Extended-reach drilling (ERD): horizontal wells with a horizontal-to-vertical ratio exceeding 2:1, used to reach distant reservoirs from a single surface location.
  • Lateral: the horizontal section of the wellbore from the heel (top of the build) to the toe (far end).
  • Multilateral: a configuration where multiple lateral branches extend from a single parent wellbore.
  • Slant well: a lower-angle deviated well common in oil sands thermal (SAGD) operations in Alberta.
  • Geosteering: real-time navigation of the lateral using LWD data to stay inside the reservoir.

Related terms: Directional Drilling, Hydraulic Fracturing, Lateral, MWD, LWD, Casing, Shale, Spud.

Frequently Asked Questions

What is horizontal drilling in oil and gas?

Horizontal drilling is the technique of drilling a wellbore that turns from vertical to near-horizontal inside the target reservoir, placing thousands of meters of pipe in direct contact with producing rock. It unlocks reservoirs that would be uneconomic to develop with vertical wells, particularly shale and tight oil plays where the reservoir rock has low permeability and requires large contact area to produce commercially.

How does horizontal drilling work?

Horizontal drilling starts as a vertical well, then uses a steerable bottomhole assembly to build inclination from vertical to horizontal at a measured rate. MWD and LWD tools continuously survey the wellbore position and read formation properties, allowing the directional driller to land the well inside a specific reservoir interval and steer along it for kilometers. After drilling, the well is cased, cemented, and hydraulically fractured in stages along the lateral.

Why is horizontal drilling important for shale production?

Shale reservoirs have permeability thousands of times lower than conventional sandstones and carbonates. A vertical well produces almost nothing from shale because the rock barely yields fluid into the wellbore. A horizontal well placed inside the shale, combined with multi-stage hydraulic fracturing, creates enough surface area and fracture connectivity to produce commercial volumes. Horizontal drilling is why US oil production doubled from 2010 to 2020 and why Canada's Montney and Duvernay have become globally significant gas supply sources.

What is the longest horizontal well ever drilled?

The longest horizontal well is generally considered to be ExxonMobil's Sakhalin-1 Chayvo Z-42, drilled in 2013 with a total measured depth of 12,700 m (41,667 ft) and a horizontal departure of 11,739 m (38,514 ft). On land, Canada's longest is the Veren Inc. Duvernay well at 9,017 m (29,583 ft) total measured depth with a 5,432 m (17,822 ft) lateral, announced in May 2024. BP's Wytch Farm in the UK set multiple records in the late 1990s with the M16 well at 11,275 m (36,992 ft) measured depth.

How much does a horizontal well cost?

A typical Permian Basin horizontal well in 2026 costs USD 6 to 9 million all-in for drilling, completion, and tie-in, with the completion (fracturing and perforating) representing roughly 55% to 65% of total cost. Montney horizontals run CAD 5 to 8 million depending on lateral length and completion intensity. Middle East multilateral horizontals in Ghawar or Rumaila can cost USD 15 to 25 million due to the complexity of the multilateral junctions and the scale of the reservoir contact.

Why Horizontal Drilling Matters in Oil and Gas

Horizontal drilling is the technology that rewrote global oil and gas supply economics after 2005, turning previously uneconomic shale and tight rock into the backbone of US and Canadian production. The Permian Basin, the Montney, the Duvernay, the Marcellus, the Bakken, the Eagle Ford, the Vaca Muerta, and the Ghawar extension wells all depend on horizontal drilling paired with completion technology. For the rig crew landing a well inside a 3 m (10 ft) pay zone, the reservoir engineer modeling EUR versus lateral length, and the commodity trader watching US production grow past 13 million barrels per day, horizontal drilling sits at the foundation of how modern hydrocarbons reach market.

Browse the Oil and Gas Glossary