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Oil and gas production

Production technology is responsible for the path of fluid from the reservoir to the gathering point: how to equip a well, how much it can deliver and how to sustain and increase the rate.

It also covers the methods of stimulating inflow: damage to the near-wellbore zone, acid treatments and hydraulic fracturing.

40 / 40 topicsWhere to start: Well completion: opening the reservoir and the tubing string

Well completions

  1. 01Well completion: opening the reservoir and the tubing stringOpen hole, slotted liner and cemented perforated casing; production up the casing and up tubing with a packer; choosing the tubing diameter, the functions of the production string and killing by circulation. Basic
  2. 02Completion string equipmentThe elements of the tubing string from the tubing hanger to the wireline entry guide and their functions: retrievable and permanent packers and setting methods, pressure and temperature forces on the packer and tubing movement, seal assemblies and expansion joints, safety valves and control line pressure, landing nipples, sliding sleeves and side-pocket mandrels. Intermediate
  3. 03Multiple-zone completions: commingled and segregated productionCommingled, simultaneous separate and alternating production of several zones by one well: a common bottomhole and crossflow through the wellbore, how water from one zone takes oil from another, dual-tubing arrangements and arrangements with zone switching, dual production with pumps and dual injection, production allocation between zones and the requirements for separate metering, intelligent completion. Intermediate
  4. 04Wireline operationsSlickline, braided line and electric line; the lubricator, stuffing box and wireline BOP for work under pressure; the tool string and jars; gauge-cutter runs, setting and pulling plugs, shifting valves, changing gas lift valves, surveys and fishing; calculation of the upward force of well pressure on the string, string weight and tension margin. Intermediate
  5. 05Horizontal wellsWhere and why horizontal wells are drilled; inflow to them in an anisotropic reservoir and the productivity improvement factor, skin and effective radius, completion options and inflow control devices, friction in the wellbore and the heel–toe effect, water and gas cresting, limitations and economics. Intermediate
  6. 06Multilateral wellsThe main bore, the laterals and the junction: multilateral well geometries, junction complexity levels under the TAML classification, the height of the junction above the reservoir, productivity of several laterals in one reservoir and in different reservoirs, when laterals start to interfere with one another, risks, cost and when a multilateral well pays back. Intermediate

Inflow and lift: nodal analysis

  1. 07Nodal analysis of the production systemThe production system from reservoir to separator, the inflow and outflow curves at a node, the operating point where reservoir and tubing performance meet and what shifts it: tubing diameter, wellhead pressure, stimulation of the reservoir, water breakthrough. Intermediate
  2. 08Inflow performance relationship (IPR)The productivity index, Vogel's equation, the composite curve, Fetkovich's method, gas inflow and forecasting the IPR as the reservoir depletes. Intermediate
  3. 09Multiphase flow in tubingThe components of the pressure gradient in tubing, slip and liquid holdup, flow regimes, correlations and mechanistic models, calculation by segments and the shape of the outflow curve. Advanced
  4. 10Chokes, surface pressure losses and well temperatureWhy a well needs a choke and how it is built; critical and subcritical flow, gas and liquid flow through a choke, Gilbert-type correlations for a gas–liquid mixture; the choke as a node of the system, the flowline, looping and separator pressure; flowing temperature by Ramey's method and the margin against wax and hydrates. Intermediate
  5. 11Effect of completion on inflowPerforation skin by the component method — shot density, phasing, tunnel length and diameter, anisotropy; the crushed zone around tunnels; tunnels that end in the damaged zone or pass through it; open hole versus perforated casing; viscous and inertial losses in gravel-filled tunnels; completion efficiency and breakdown of the measured skin. Advanced
  6. 12Well performance sensitivity analysisA systematic run through the variants of nodal analysis: what limits the rate — the reservoir or the tubing, the best tubing size now and years ahead, wellhead pressure, water cut, gas–oil ratio, skin factor and stimulation, elasticities and the tornado chart, the natural flow limit and the time to switch to artificial lift, the order of calculation in software. Intermediate

Artificial lift

  1. 13Artificial lift: when it is needed and how to choose the methodWhen a well needs a pump or gas lift, how they change the pressure in the well, how gas lift, sucker-rod pumps, electric submersible pumps, progressing cavity pumps and jet pumps differ, and how to choose a method by rate, depth, gas, sand and whole-life cost. Intermediate
  2. 14Sucker-rod pumpingThe pumping unit, the rod string and the plunger pump with two valves; the pumping cycle, theoretical displacement and volumetric efficiency, rod loads and loss of stroke, reading the dynamometer card, dynamic fluid level and pumping mode, gas and other problems. Intermediate
  3. 15Electric submersible pumps (ESP)The layout of an ESP system from the control panel to the sensors, the stage and the pump performance curve, selecting a pump by required head, number of stages and power, the affinity laws and variable-frequency control, gas at the intake, the motor and cable, signs of malfunction. Intermediate
  4. 16Hydraulic pumps: piston and jetAn installation with power fluid, open and closed circuits, the hydraulic piston pump — the P/E ratio, pressures, number of strokes and power-fluid rate — the jet pump — nozzle, throat, dimensionless characteristics, efficiency and cavitation — with sizing examples. Intermediate
  5. 17Progressing cavity pumps and hybrid systemsThe rotor, stator and moving cavities, displacement volume, flow rate and slippage, torque, power and rod twist, choice of elastomer and interference fit, viscous oil and sand; combined systems — a submersible motor instead of rods, gas lift above the pump — and insert pumps. Intermediate

Gas lift

  1. 18Gas lift: principles and choice of operating conditionsHow injected gas lightens the liquid column, injection pressure and the depth of gas injection, the rate-versus-gas-rate curve with technical and economic optima, allocating limited gas between wells, continuous and intermittent gas lift and the energy needed to compress the gas. Intermediate
  2. 19Unloading a gas lift well: valves and mandrelsWhy gas does not reach the operating valve at once and how unloading valves displace the workover fluid from the top down; the design of a bellows valve with a nitrogen dome, valves operated by gas pressure and by tubing pressure; opening and closing pressures from a force balance and the order in which unloading valves close; setting on a test rack with a correction for the temperature of the nitrogen; gas flow through the seat and choice of the orifice of the operating valve. Advanced
  3. 20Gas lift designThe design of a gas lift installation for a hypothetical well: the point of balance and the depth of the operating valve, spacing of unloading valves with a pressure step, a design line and a minimum interval, selection of seats and the setting sheet, gas system pressure and the compressor, bracketing mandrels to allow for falling pressure and rising water cut, intermittent gas lift with a plunger. Advanced
  4. 21Gas lift operation and optimisationHow gas lift wells are run: what is measured, how to find where gas enters from the wellhead gas pressure and a survey along the wellbore, the signs and causes of malfunction — multipoint injection, a hole in the tubing, heading and gas storage in the annulus — allocating gas across the field with minimum gas use and a limit on water, separator pressure and the compressor, intermittent gas lift in operation, new equipment. Advanced

Perforating

  1. 22Shaped-charge perforatingHow an explosion turns the charge liner into a jet and why it penetrates steel and rock, the density law, deep-penetrating and big-hole charges, hollow-carrier, expendable and through-tubing guns, shot density and phasing, the charge specification against the tunnel in the formation, the crushed zone and cleaning the tunnels by underbalance. Intermediate
  2. 23Perforating operations: gun conveyance and proceduresConveying guns on wireline, on tubing, on coiled tubing and on slickline; underbalance during perforating — the field criterion, limits and calculating the liquid level in the tubing; depth correlation with the gamma ray log and casing collar locator; oriented perforating, extreme overbalance and propellant gas generators; clusters and limited entry in hydraulic fracturing; safety principles. Intermediate

Formation damage and stimulation

  1. 24Formation damage and damage skinHow damage to the near-wellbore zone reduces the rate, the mechanisms of pore plugging and phase blocking, damage skin from the reduced-permeability zone model, and the choice: prevent, remove or bypass. Intermediate
  2. 25Sources of formation damageDamage by operation: drilling (particles and filtrate, clay swelling and migration, water and emulsion blocks), cementing, perforating, production (fines and critical velocity, scales and the saturation index, wax and asphaltenes), injection and incompatible waters, well killing and workover; return permeability and compatibility tests, diagnosis and prevention. Intermediate
  3. 26Acid treatments: principle, economics and candidate selectionWhat acid does in sandstone and in carbonate, why the value of a treatment is set by the damage skin removed, how to estimate the gain in rate and the payback period and how to select candidate wells. Intermediate
  4. 27Acid systems and treatment designReactions of hydrochloric and hydrofluoric acids with carbonates, quartz and clays, dissolving power and the volume of rock dissolved, mud acid strength chosen from mineralogy, the stages of a sandstone treatment with volumes per metre, additives, secondary and tertiary precipitates, diversion, the maximum rate and injection pressure below fracture pressure, flowback and evaluation by skin. Advanced
  5. 28Acid treatment of carbonates and special wellsWormholes in carbonates: dissolution regimes, the Damköhler number, the acid efficiency curve and the optimum injection rate, acid volume and rate for a given wormhole length; diversion of acid between layers; treatments of long horizontal wells and injectors, gravel packs and fractured formations; acid fracturing versus matrix treatment; evaluating treatment campaigns against a declining baseline. Advanced
  6. 29Hydraulic fracturing: purpose and well selectionHow a fracture forms, its half-length, conductivity and dimensionless conductivity, the equivalent skin and the folds of increase in rate, selecting wells and choosing between acid and a fracture, the stages and types of fracturing. Intermediate
  7. 30Inflow to a hydraulically fractured wellThe effective wellbore radius of a fracture at any dimensionless conductivity and its asymptotes, the dimensionless productivity index in a closed area and its limit, bilinear, linear and pseudo-radial flow and their duration, why the first rates overstate the effect, the skin of a choked fracture and of the fracture faces. Advanced
  8. 31Rock mechanics for hydraulic fracturingThe three principal stresses and a poroelastic estimate of the minimum horizontal stress with the Biot coefficient and tectonic strain; stress concentration at the borehole wall and breakdown pressure with and without fluid penetration; closure pressure from a mini-frac and the G-function, extension pressure from a step-rate test; net pressure, fracture width and its height growth against stress contrast; fracture and perforation orientation. Advanced
  9. 32Fracture design: size and conductivityProppant and fracture conductivity in the reservoir — closure stress, embedment, polymer residue, inertial losses; the proppant number, the optimum dimensionless conductivity and fracture dimensions; the PKN, KGD and radial models; volume balance with leak-off, fluid efficiency from a mini-frac, the pad and the proppant concentration schedule. Advanced
  10. 33Fracturing fluids and tip-screenout fracturingRequirements for a fracturing fluid and its types — slickwater, linear and crosslinked gels, viscoelastic surfactants, foams, breakers; the power-law model and apparent viscosity in pipe, in the fracture and around a settling grain; the leak-off coefficient from filter cake, filtrate and the compressibility of the reservoir; proppant settling and transport; tip-screenout fracturing — the pad, the time to screenout, packing and the rise in net pressure; quality control. Advanced

Sand production

  1. 34Sand production: types, prediction and cost of the problemWhy a reservoir produces sand; rock strength — uniaxial and triaxial compression, the Mohr–Coulomb criterion, the thick-walled cylinder, estimation from logs and its scatter; stresses at the cavity wall, critical drawdown and critical depletion; transient, continuous and catastrophic sand production, its consequences, cost and sand management. Intermediate
  2. 35Sand control methodsHow screens and gravel retain sand; sieve analysis and the uniformity coefficient; sizing gravel from the ratio of median sizes and the screen slot; types of screen; gravel packing in open and cased hole, placing the pack and checking it; frac-pack; chemical consolidation; choosing a method and monitoring performance. Intermediate

Facilities and processing of production

  1. 36Field development concepts: surface facilitiesWhat field facilities consist of: the path of production from the wellhead to custody transfer, facility loads over the life of the field and the balance of associated gas, well pads, gathering and the central processing facility onshore, platforms, floating units, subsea wells and artificial islands offshore, phased start-up and choosing an option by NPV under uncertain reserves — with examples from Tengiz, Karachaganak and Kashagan. Intermediate
  2. 37Oil treating: separators, dehydration, desalting and stabilisationRequirements for commercial crude under the technical regulation of the Eurasian Economic Union (EAEU) and the route of its treatment; two- and three-phase, horizontal and vertical separators and their internals; checking a separator for gas (the Souders–Brown equation) and for liquid (retention time, settling of droplets by Stokes' law); emulsions and breaking them by heat, demulsifiers and an electric field; desalting with wash water; stabilisation and vapour pressure; tanks, custody metering and net oil mass. Intermediate
  3. 38Gas processing and compressionRequirements for sales gas under the technical regulation of the Eurasian Economic Union (EAEU); water content and dew point (the Bukacek correlation); hydrates and the methanol calculation with the Hammerschmidt equation; glycol and adsorption dehydration; removal of hydrogen sulfide and carbon dioxide, sulfur and the Claus process; hydrocarbon dew point, low-temperature separation and recovery of natural gas liquids; compressors, number of stages, discharge temperature and power; gas processing projects in Kazakhstan. Intermediate
  4. 39Produced water: composition, treatment and disposalWhat produced water contains; how oil droplets are separated from water — Stokes' law, surface loading of a settling tank, plate separators, hydrocyclones, flotation, filters; how oil in water is measured; scale, corrosion and hydrogen sulfide in the treatment system; reinjection, disposal wells or discharge under the laws of Kazakhstan; the water balance of a field. Intermediate
  5. 40Water injection systemsThe pressure maintenance system from source to reservoir: produced, aquifer, sea and fresh water, compatibility of waters and scaling on mixing, quality requirements and particle size, deaeration and oxygen scavengers, pumping stations and losses at throttling, injectivity, wellhead pressure and fracture propagation pressure, monitoring injection with the Hall plot. Intermediate

This section is growing: new topics are published after a technical review.