Technical Estimation: The Engineering Calculator Suite
A comprehensive reference to every engineering calculator in Oil and Gas PDT. This guide covers the full calculator suite organised across 7 categories, detailing the sizing methodologies, applicable standards, output specifications, and reference project configurations available for each.
1. Overview
The Technical Estimation module is the engineering foundation of Oil and Gas PDT. It comprises a verified, standards-cited suite of engineering calculators organised into seven categories -- growing every release -- spanning the full scope of upstream oil and gas facility design. Each calculator performs three integrated functions: it sizes equipment according to recognized engineering standards, it generates technical specifications suitable for inclusion in engineering deliverables, and it produces parametric cost estimates with P90/P50/P10 confidence intervals.
The calculators are designed for the conceptual and pre-FEED phases of project development, where speed and breadth of analysis take priority over the detailed precision required in later engineering phases. A single engineer can evaluate an entire facility concept -- from wellhead to export terminal -- in hours rather than weeks, enabling rapid comparison of development alternatives and early identification of cost drivers and technical constraints.
The following table summarises the seven categories:
| Category | Standards Basis | Primary Focus |
|---|---|---|
| Quick Project Estimation | Outturn-calibrated correlations | Whole-facility conceptual sizing |
| Process Equipment | API 12J/12K, TEMA, GPSA | Separation, treatment, gas processing |
| Rotating Equipment | API 610/616/617/618 | Compression, pumping, power generation |
| Utilities and Infrastructure | ASME, API 526, IEC 60079 | Electrical, HVAC, safety, piping, metering |
| Subsea Systems | API 17D/17F/17J/17K/17N | Subsea trees, flowlines, processing |
| Wells and Drilling | Offset-well correlations | Well design, drilling, artificial lift |
| Emissions and Sustainability | Marginal abatement cost | Emissions reduction equipment |
| All categories | API · ASME · TEMA · GPSA · AACE |
The sections that follow describe each category in detail, identifying the individual calculators, the engineering standards they implement, and the types of outputs they produce. For general guidance on navigating the Technical Estimation module and interpreting results, see the Getting Started guide.
2. Quick Project Estimation
The Quick Project Estimation category provides rapid conceptual sizing tools for entire facility concepts. Unlike the equipment-level calculators in subsequent categories, these tools operate at the system or facility level, generating order-of-magnitude capital cost estimates suitable for concept screening, portfolio ranking, and initial opportunity assessment. They are the first tools most users reach for when evaluating a new development opportunity.
2.1 Platform Concept and Sizing
Estimates the capital cost and key design parameters for fixed and floating platform concepts based on production capacity, water depth, environmental conditions, and host infrastructure constraints. The calculator covers jacket platforms, gravity-based structures, compliant towers, tension leg platforms (TLPs), semi-submersibles, and spars. Outputs include estimated topsides weight, substructure weight, total installed cost breakdown (engineering, procurement, fabrication, installation, hook-up and commissioning), and indicative schedule duration.
The sizing methodology uses correlation-based models derived from a database of over 120 platform projects executed between 2005 and 2024 across four geographic regions. Water depth, processing capacity, and accommodation requirements are the primary independent variables.
2.2 Floating Units (FPSO / FLNG / FSRU / FSO / FSU)
Provides conceptual cost estimation for floating production, storage, and offloading facilities. The calculator supports five vessel types: FPSO (Floating Production Storage and Offloading), FLNG (Floating Liquefied Natural Gas), FSRU (Floating Storage and Regasification Unit), FSO (Floating Storage and Offloading), and FSU (Floating Storage Unit). Key inputs include processing capacity, storage volume, hull type (new-build vs. converted), mooring system (spread mooring, internal turret, external turret, disconnectable), and environmental severity.
Outputs include an overall CAPEX estimate broken down by hull, topsides, mooring, risers, and integration, as well as indicative delivery schedules and operating cost benchmarks. The database includes reference data from more than 60 floating units delivered between 2010 and 2024.
2.3 Pipelines and Export Systems
Estimates capital costs for offshore and onshore pipeline systems based on diameter, length, wall thickness, material grade, installation method (S-lay, J-lay, reel-lay), and terrain or seabed conditions. The calculator covers production flowlines, export trunklines, gas pipelines, and multiphase transport lines. Cost models differentiate between pipe material, coating, welding, installation vessel spread, shore approach, and landfall costs. Regional adjustment factors account for the substantial cost differences between benign shallow-water pipe-lay and harsh-environment deepwater installation.
2.4 Cables and Umbilicals
Covers subsea power cables, fiber-optic communication cables, and dynamic and static umbilicals for subsea production control. The calculator estimates costs based on cable/umbilical type, length, voltage (for power cables), number of cores, and water depth. Installation method (plow burial, jet trenching, rock dumping) is factored into the total installed cost. This calculator is particularly important for tieback developments where the umbilical and cable costs can represent 10-20% of the total subsea CAPEX.
2.5 Decommissioning and Abandonment
Estimates the cost of decommissioning and removing oil and gas infrastructure at the end of field life. The calculator covers well plugging and abandonment, topsides removal (including heavy-lift vessel costs), jacket or substructure removal, pipeline decommissioning (removal, in-situ decommissioning, or burial), and site clearance verification. Costs are estimated based on the scope and scale of installed infrastructure, water depth, and regional regulatory requirements. Decommissioning cost estimates feed directly into the financial model as end-of-life abandonment expenditure (ABEX).
3. Process Equipment
The Process Equipment category addresses the core process train of an oil and gas production facility. These calculators size the equipment responsible for separating, treating, and conditioning the produced fluids into saleable products. Each calculator implements recognized industry sizing methodologies and generates both technical specifications and parametric cost estimates.
3.1 Three-Phase Separators
Standard: API 12J (Specification for Oil and Gas Separators)
Sizes horizontal and vertical three-phase separators for gas-oil-water separation. The calculator determines vessel diameter and length based on gas capacity (Souders-Brown equation for gas velocity), liquid retention time requirements (oil-water separation), and operating pressure/temperature. Key inputs include fluid flow rates, GOR, water cut, fluid properties (API gravity, gas specific gravity, viscosity), operating conditions, and design criteria (retention time, surge volume, mist extractor type). Outputs include vessel dimensions, wall thickness (per ASME Section VIII), estimated weight, and installed cost at P90/P50/P10 confidence levels.
3.2 Heat Exchangers
Standards: TEMA (Tubular Exchanger Manufacturers Association), API 661 (Air-Cooled Heat Exchangers)
Covers shell-and-tube, plate, and air-cooled heat exchangers. The calculator estimates required heat transfer area from duty, log mean temperature difference (LMTD), and overall heat transfer coefficient. It supports all standard TEMA configurations (BEM, AES, AEP, etc.) and determines shell diameter, tube count, baffle spacing, and overall dimensions. For air-cooled exchangers, it calculates the number of bays, fan power, and plot area. Cost estimation accounts for material of construction, pressure rating, and surface area using power-law scaling.
3.3 Oil Treatment
Standard: API 12K (Indirect-Type Oil-Field Heaters)
Sizes oil treatment equipment including heater-treaters, electrostatic coalescers, and desalting systems. The calculator determines the equipment capacity required to reduce water content and salt content in the crude oil to pipeline or export specification. Heater duty, residence time, and electric field sizing are calculated based on the crude oil properties and target specification.
3.4 Water Treatment
Standard: API 12R1 (Setting, Maintenance, Inspection, and Repair of Tanks in Production Service)
Covers produced water treatment systems including hydrocyclones, flotation units (induced gas flotation, compact flotation units), walnut shell filters, membrane systems, and water injection facilities. The calculator determines equipment sizing to meet discharge or reinjection water quality specifications (typically oil-in-water content below 30 ppm for discharge, below 5 ppm for reservoir injection). Costs include the complete treatment train from separator water outlet through final disposition.
3.5 Gas Processing
Standard: GPSA (Gas Processors Suppliers Association Engineering Data Book)
Sizes gas dehydration (TEG, molecular sieve), gas sweetening (amine), and gas conditioning equipment. The calculator determines contactor tower dimensions, regeneration system sizing, chemical consumption rates, and utility requirements. For amine systems, it calculates the lean amine circulation rate, reboiler duty, and acid gas volumes for disposal or sulfur recovery. For dehydration systems, it determines the glycol circulation rate and stripping gas requirements to meet pipeline water dew point specifications.
3.6 LPG Processing
Covers NGL recovery and fractionation systems. The calculator sizes de-ethanizer, de-propanizer, and de-butanizer columns, as well as cryogenic turbo-expander plants and refrigerated absorption systems. Inputs include feed gas composition, pressure, temperature, and target NGL recovery. Outputs include column dimensions, reboiler and condenser duties, refrigeration requirements, and product yields (ethane, propane, butane, natural gasoline). Cost estimation includes the complete fractionation train, product storage, and loading facilities.
3.7 LNG Processing
Estimates the capital cost and key parameters for LNG liquefaction systems. The calculator supports major liquefaction technologies including C3MR (propane pre-cooled mixed refrigerant), AP-X, Cascade (ConocoPhillips Optimized Cascade), and dual mixed refrigerant (DMR). Inputs include feed gas flow rate and composition, ambient temperature, and target LNG production rate. The calculator estimates liquefaction train cost, utility requirements, gas shrinkage (fuel and losses), and the associated LNG storage tank capacity. This calculator connects directly with the financial model's LNG value chain module for integrated project economics.
4. Rotating Equipment
Rotating equipment represents a significant portion of both capital cost and operational complexity in upstream facilities. Compressors, pumps, and power generators are critical to production throughput, and their sizing directly influences the facility's power demand, weight, and plot space. The calculators in this category cover the primary rotating equipment classes encountered in upstream developments.
4.1 Compression Systems
Standards: API 617 (Axial and Centrifugal Compressors), API 618 (Reciprocating Compressors), API 619 (Rotary-Type Positive-Displacement Compressors)
Sizes gas compression systems for gas lift, gas export, gas injection, flash gas recovery, and vapor recovery service. The calculator determines compressor type selection (centrifugal vs. reciprocating), number of stages, interstage cooling requirements, driver type (gas turbine, electric motor, gas engine), and absorbed power. Polytropic efficiency, discharge temperature limits, and speed ranges are calculated according to the applicable API standard. Cost estimation includes the compressor package (compressor, driver, gearbox, lube oil system, control panel), piping, and installation. Compression is often the single largest power consumer on an offshore platform, making this calculator critical for overall facility sizing.
4.2 Pumping Systems
Standards: API 610 (Centrifugal Pumps), API 676 (Positive Displacement Pumps)
Covers centrifugal and positive displacement pumps for crude oil export, water injection, chemical injection, firewater, and utility services. The calculator determines pump type selection based on flow rate, differential head, fluid properties (viscosity, specific gravity, solids content), and NPSH available. It calculates hydraulic power, pump efficiency, driver sizing, and material selection for wetted components. For high-pressure water injection service, the calculator sizes multi-stage barrel pumps capable of delivering 200+ bar discharge pressure. Cost estimation includes the pump, driver, coupling, baseplate, and associated piping and instrumentation.
4.3 Power Generation
Standard: API 616 (Gas Turbines for the Petroleum, Chemical, and Gas Industry Services)
Sizes the power generation system for the entire facility based on the aggregated electrical load from all equipment. The calculator supports gas turbine generators, diesel generators, dual-fuel generators, and waste heat recovery (combined cycle) configurations. It determines the number of generating units, individual unit rating, fuel gas consumption, and waste heat availability. The N+1 redundancy philosophy is applied by default, with the ability to configure N+2 for critical applications. Cost estimation includes the generating units, switchgear, power distribution, UPS systems, and emergency power.
5. Utilities and Infrastructure
Utilities and infrastructure systems are often underestimated in early-phase project evaluations, yet they typically represent 25-35% of total topsides weight and 20-30% of total installed cost. The calculators in this category ensure that these essential systems are properly sized and costed from the earliest project phases.
5.1 Electrical Systems
Sizes the complete electrical distribution system from the main power bus through to final motor control centres. Covers medium voltage (6.6 kV, 11 kV) and low voltage (400 V, 690 V) distribution, transformers, variable speed drives, motor starters, cable sizing, and grounding systems. The calculator estimates equipment quantities and costs based on the connected load profile and the facility's area classification (Zone 1, Zone 2 hazardous areas per IEC 60079).
5.2 HVAC and Buildings
Covers heating, ventilation, and air conditioning systems for accommodation modules, control rooms, electrical rooms, and other enclosed spaces. Also estimates costs for accommodation modules (based on personnel count and standard), helidecks, laydown areas, and temporary construction facilities. Climatic conditions (ambient temperature, humidity, wind exposure) and safety requirements (HVAC overpressure for gas ingress protection) are factored into the sizing and cost calculation.
5.3 Safety Systems
Sizes fire and gas detection systems, fire suppression (deluge, foam, CO2, dry chemical), emergency shutdown systems (ESD), blowdown systems, and pressure safety valves (per API 526). The calculator estimates the number and type of detectors, suppression agent quantities, relief valve sizing, and flare system capacity. Safety system costs are estimated based on the process hazard analysis requirements implied by the facility's process inventory, pressure levels, and manning philosophy.
5.4 Instrumentation and Control
Covers Distributed Control Systems (DCS), Safety Instrumented Systems (SIS), field instruments (transmitters, analyzers, switches), control valves, and operator workstations. The calculator estimates instrument counts based on equipment count and process complexity, then applies cost-per-instrument benchmarks calibrated by system type and SIL rating. Telecommunication systems (PAGA, radio, CCTV, marine communications) are included as a scope option.
5.5 Valves Sizing
Sizes control valves, on/off valves, and safety relief valves for the process facility. The calculator determines valve Cv requirements, body size, pressure class, material selection, and actuator type. It supports gate, globe, ball, butterfly, and check valve types across the standard ASME pressure classes (150 through 2500). Valve quantity estimation is based on the P&ID complexity implied by the upstream process equipment selections, providing a systematic approach to valve cost estimation at the conceptual phase.
5.6 Process Piping
Estimates the cost of facility piping systems based on the process equipment register and general arrangement. The calculator uses piping-to-equipment cost ratios (validated against executed project data) combined with material, diameter distribution, and insulation/heat tracing requirements to produce a parametric piping estimate. This approach is well-suited to the conceptual phase where detailed pipe routing and isometric drawings are not yet available. The calculator differentiates between carbon steel, stainless steel, duplex, and GRE piping systems.
5.7 Fiscal Metering
Sizes custody transfer metering systems for oil and gas export streams. The calculator covers ultrasonic meters, turbine meters, Coriolis meters, and orifice plate systems, with prover loop sizing and sampling system requirements. Metering system accuracy class (fiscal vs. allocation) and redundancy requirements (duty and standby streams) are configurable. Cost estimation includes the meter runs, proving systems, sampling systems, flow computers, and associated piping and structures. Fiscal metering costs are often underestimated in early project phases but can represent a significant capital outlay, particularly for multi-product export facilities.
6. Subsea Systems
Subsea production systems represent a specialized and increasingly important segment of upstream facility design. As the industry moves into deeper water and more remote locations, subsea tieback architectures have become the dominant development concept for many new fields. The calculators in this category cover the primary subsea equipment categories, enabling integrated subsea-to-topside concept evaluation.
6.1 Subsea Production Systems
Standards: API 17D (Design and Operation of Subsea Production Systems -- Subsea Wellhead and Tree Equipment), API 17F (Subsea Production Control Systems)
Sizes and costs subsea wellheads, subsea trees (vertical and horizontal), manifolds, and production control systems. The calculator determines the equipment specification based on water depth, well count, production rates, pressure and temperature ratings, and intervention philosophy (workover riser vs. riserless intervention). Costs cover the subsea tree assembly, manifold, template, SCSSV, downhole safety valve, and the associated tooling and installation spread. The database includes reference costs for standard-bore (5-1/8 inch) and large-bore (7-1/16 inch) tree configurations across pressure ratings from 5,000 psi to 20,000 psi.
6.2 Flowlines and Risers
Standards: API 17J (Specification for Unbonded Flexible Pipe), API 17K (Specification for Bonded Flexible Pipe)
Covers subsea flowlines (rigid and flexible), risers (steel catenary, flexible, top-tensioned, hybrid), and associated ancillaries (pipeline end terminations, in-line tees, pig launchers/receivers). The calculator estimates costs based on pipe diameter, length, wall thickness, material grade (X65, X70, 13Cr, duplex), insulation type (wet insulation, pipe-in-pipe, electrically heated), and installation method. For deepwater applications, the calculator accounts for the riser system dynamic response and fatigue life requirements that influence material selection and wall thickness beyond static pressure containment needs.
6.3 Subsea Processing
Standard: API 17N (Recommended Practice for Subsea Production System Reliability and Technical Risk Management)
Covers emerging subsea processing technologies: subsea boosting (multiphase pumping, wet gas compression), subsea separation (gas-liquid, oil-water), subsea water injection, and subsea power distribution. These technologies are increasingly deployed to extend tieback distances, improve recovery factors, and reduce topside processing requirements. The calculator estimates equipment costs based on capacity, water depth, power requirements, and technology maturity level. Given the relatively limited installed base of subsea processing equipment, cost uncertainty ranges are wider than for conventional topsides equipment, and the calculator explicitly flags this in its confidence interval reporting.
7. Wells and Drilling
Wells represent the single largest capital expenditure item in most upstream developments, often accounting for 40-60% of total project CAPEX. The calculators in this category cover the complete well lifecycle from initial design and drilling through completion, production optimisation, and intervention.
7.1 Well Design and Completion
Defines the well architecture from surface to total depth, including casing design (conductor, surface, intermediate, production, liner), cement program, completion type (open hole, cased-and-perforated, gravel pack, frac pack, intelligent completion), and downhole equipment (packers, gauges, inflow control devices, sand screens). The calculator estimates the total well cost by summing the individual contributions from each casing string, cementing operation, completion component, and wellhead assembly. Well cost is driven primarily by measured depth, number of casing strings, completion complexity, and whether the well is vertical, deviated, or horizontal.
7.2 Drilling Operations
Estimates drilling campaign costs based on rig type (jack-up, semi-submersible, drillship, land rig, platform rig), rig day rate, estimated drilling days per well, number of wells, mobilization/demobilization costs, and drilling consumables (bits, mud, cement, casing). The calculator supports batch drilling, pad drilling, and conventional single-well drilling scenarios. Estimated drilling days are derived from offset well data correlations indexed by measured depth, formation difficulty, and hole section count. Non-productive time (NPT) is modelled as a percentage adder calibrated by regional experience data.
7.3 Artificial Lift Systems
Sizes artificial lift systems for wells that cannot flow naturally at economic rates. The calculator supports electric submersible pumps (ESP), gas lift (continuous and intermittent), sucker rod pumps, progressive cavity pumps (PCP), jet pumps, and plunger lift. Selection guidance is provided based on production rate, fluid properties (GOR, water cut, viscosity, solids), well geometry (depth, deviation, dogleg severity), and power availability. Cost estimation includes the downhole equipment, surface facilities (gas lift compressor or ESP power supply), and the anticipated intervention frequency for equipment replacement over the well life.
7.4 Well Intervention
Estimates the cost of well intervention and workover activities over the field life. The calculator covers wireline operations, coiled tubing interventions, snubbing, workover (pulling tubing), and sidetrack drilling. Costs are estimated per intervention event based on the type of operation, well access method (platform rig, workover riser, riserless intervention), and vessel or rig day rate. A lifecycle intervention schedule can be configured based on failure rate assumptions for downhole equipment (ESP mean time between failures, gas lift valve reliability), producing a total intervention OPEX estimate over the project life that feeds into the financial model.
8. Emissions and Sustainability
The energy transition and tightening environmental regulations have made emissions reduction a first-order design consideration for new upstream developments. The Emissions and Sustainability calculator addresses this by sizing and costing equipment specifically aimed at reducing greenhouse gas emissions and improving the environmental performance of production facilities.
8.1 Emissions Reduction Equipment
This calculator covers seven categories of emissions reduction equipment, each addressing a different source of operational emissions:
For each emissions reduction technology, the calculator estimates both the capital cost and the emissions reduction benefit (tonnes CO2e per year). This enables users to compute a marginal abatement cost ($/tonne CO2e avoided) for each measure, facilitating rational prioritisation of emissions reduction investments. The abatement cost can be compared against carbon pricing assumptions in the financial model to determine whether a given investment is economically justified under different carbon price scenarios.
9. Standards Compliance
Every calculator in Oil and Gas PDT implements sizing methodologies derived from recognized international standards. This ensures that the outputs are defensible, auditable, and consistent with the expectations of project partners, regulators, and lending institutions. The following is a comprehensive list of the standards referenced across the calculator suite.
American Petroleum Institute (API)
Other International Standards
Standards compliance does not mean that the platform produces Class 1 detailed engineering. It means that the conceptual sizing methodologies are derived from, and consistent with, the principles established in these standards. The results are appropriate for Class 5 estimation and will not produce contradictions when the design progresses to detailed engineering under the same standards. This consistency is important for ensuring continuity across project phases and avoiding costly re-baseline exercises during FEED.
10. Reference Project System
One of the most powerful features of the Technical Estimation module is the Reference Project System. Every calculator in the platform offers a library of pre-loaded reference configurations based on real-world installations. These references serve as starting points for new analyses, enabling engineers to begin with a realistic baseline rather than a blank input form.
What Reference Projects Contain
Each reference project contains a complete set of input parameters for a specific calculator, representing a specific equipment configuration that was designed, fabricated, and installed in a real-world project. The reference includes the design basis (flow rates, pressures, temperatures, fluid properties), equipment specifications (dimensions, materials, internals), and the associated cost data (adjusted to the current base year using RICEI escalation).
Reference projects are described by a label that identifies the geographic region, field type, and key design parameter. For example, a separator reference might be labeled "North Sea 15,000 bopd LP Separator" or "GOM Deepwater 80,000 bopd HP Separator." This labeling convention allows users to quickly identify the reference most relevant to their design case.
Data Provenance
Reference data is sourced from three channels: publicly available project disclosures (operator presentations, regulatory filings, annual reports), commercially available cost databases and benchmarking studies, and direct industry contributions from engineering consultancies and operating companies. All reference data is anonymized to protect commercial confidentiality. Specific project names, operator identities, and vendor proprietary information are never disclosed.
Each reference entry is tagged with a data quality indicator reflecting the provenance and confidence level of the source data. References derived from detailed project outturn reports carry the highest quality rating, while references derived from published literature or conference papers carry a lower (but still useful) rating.
How Reference Projects Accelerate Estimation
The primary benefit of the reference system is speed. Rather than populating 15 to 30 input fields from scratch for each calculator, an engineer can load a relevant reference, adjust the two or three parameters that differ from their specific case, and run the calculation immediately. This reduces the time to complete a full facility estimate from days to hours.
A secondary benefit is calibration. By comparing the calculator's output against the known cost of the reference installation, users can develop an intuitive feel for the accuracy and reliability of the parametric models. If the calculator produces a cost estimate for a known reference that is within 15% of the actual cost, the user can have reasonable confidence that extrapolations to similar (but not identical) configurations will be in the right ballpark.
The reference database is updated annually with new project data, and existing references are reviewed and recalibrated as more outturn information becomes available. The total reference library currently contains over 400 individual reference configurations across the full calculator suite.