Anchor Latch Seal Assembly is used for completions where tubing movement is not desirable. The seal assembly is run in to the polished seal bore and anchor latch is snapped in to the profile at the top of the seal bore with set down weight. Assembly is released when required by upward pull and right hand turn. Standard anchor latch assemblies are manufactured from materials that comply with NACE standards for sulfide stress cracking-resistant metallic materials. Viton, Aflas, and Chevron seals are used with material suitable for pressure, temperature and corrosive environment specific to the application.

Barefoot DST is performed in the open hole. The hole is usually cased just before drilling into the zone of interest. A new hole is drilled below the casing through the zone planned to be tested. Once complete zone is opened, DST tools are run in the well and attempts are made to flow the well in a controlled manner.

Bridge plugs are used for zonal isolation or suspension. They are made up of cast iron, brass, aluminum and rubber parts. Bridge plugs can be set on wireline, slickline or drill pipe.

Brine is water with high salt concentration. It contains salts such as sodium, calcium, or bromides in solution. Brine is commonly produced along with oil from the reservoir. Various brine formulations are also used as completion fluid where salt is used to increase fluid density. It is also used for drilling in sensitive formations where either clay swelling is expected or where solid particles as weighting agent could cause formation damage.

Brines formulations can be prepared to achieve densities ranging from 8.4 to over 20 ppg. Common salts used in the preparation of simple brine systems include sodium chloride, calcium chloride, and potassium chloride. Complex brine systems may contain zinc, bromide, or iodine salts, but these brines are more corrosive and costly.

BS&W is a very commonly used acronym in oil & gas industry. It stands for Basic Sediments and Water. When reservoir fluid flows to surface, the flow of reservoir fluid includes water and suspended particles of impurities like dirt, sand, paraffin, scale, rust etc. BS&W varies greatly from field to field. Water and suspended particles are separate from reservoir fluid before taking measurement during well testing and prior to transporting hydrocarbons to production facilities.

Cased Hole DST is the process of testing the wells after running production casing or liner. Once a well is drilled to the target reservoir, various logs are run for evaluating reservoir characteristics. Based on log evaluation, prospective zones are identifies. Formation type is identified through Gamma Ray signatures, potentials of oil and gas are identified through resistivity logs and porosity is identified through porosity log etc. The prospective zone is identified through positive combination of these logs. Well is cased with production casing or liner cemented in place to provide zonal isolation. Casing / Liner and well are perforated across selected potential zone and is tested by running DST string inside cased hole.

Champ packer is a Halliburton tool. It is a retrievable packer with bypass ports and hold-down slips. Champ Packer is widely used for Drill Stem Testing and Tubing Conveyed Perforation applications. A concentric bypass valve provides a larger flow area and allows circulation below the packer. Champ packer has higher temperature and pressure ratings. It is ideal for deepwater and extended reach wells.

Coil Tubing is a continuous string of flexible steel pipe that wound on a reel. Coil tubing is normally hundreds to thousand of feet long. The coil tubing reel is mounted on the coil tubing unit which also has other devices and controls for lowering the coil tubing into the well by unwinding and pull it out to rewind on the reel.

Coil Tubing

Control lines are metal tubes that are used for conveying hydraulic pressure from control unit to the downhole equipment to be operated. In completion or testing mode, the control lines run along the tubing from surface to the downhole tool like ‘Sub-surface safety valve’. It is connected to the control panel on rig / platform, which is used for operating the downhole tool.

Control line protectors are special clamps that are wrapped around the control line and tubing to keep control line in place.

Once a well is landed across the zone of interest and the production casing / liner has been run, the well is perforated using guns loaded with shaped charges. The the firing of guns create perforation tunnels through the pipe and formation. The impact of shaped charges create a zone of reduced permeability around perforation tunnels, which is called the crushed zone. Crushed zone tends to reduce the flow of formation fluid into the well through peroration tunnels.

Distributed Temperature Sensing is a technique of measuring temperature along the wellbore using Fiber Optics Technology. A laser beam is shot down the fiber optic cable. The reflection of the beam is affected by newly excited atoms. Analysis of frequency shift of the reflection and the time of return signal provides information about the instantaneous temperature along with fiber optic cable.

DrillGun Assembly is Halliburton's drillable perforating system. The assembly is drill pipe conveyed and includes aluminum guns with charges and drillable squeeze packer.

Testing or widely known as Drill Stem Testing (DST) is the process of determining reservoir potential. Once the well is drilled to the target formation, DST tools are run in the well and attempts are made to flow the well to surface in a controlled manner. Various surface and downhole measurements are carried out which help in evaluating the reservoir potentials. Broadly speaking, DSTs are two kinds, Bare Foot DST (open hole DST) or Cased Hole DST.

ESP is an abbreviation of 'Electrical Submersible Pump'. When a reservoir does not have enough energy to flow naturally, artificial lifting techniques are used to flow the formation fluid to the surface. The most adopted artificial lift method is ESP. An Electrical Submersible Pump houses multiple centrifugal pump stages mounted in series coupled to a submersible electrical motor. This assembly is lowered in the well and is connected to controls at the surface. Multiple stages of ESP connected in a series use impeller and diffuser arrangements to increase the flow pressure. The ESP stages are designed so that after the last stage, fluid attains enough pressure to flow to the surface naturally.

ESP Article

EZSV, a Halliburton tool is an easily drillable squeeze packer. It's primarily used for squeeze cementing but can also be used as bridge plug for zonal isolation or abandonment. This tool can be run on wireline, slickline or drill pipe and is designed to offer little resistance to drill out.

Easy Drill Cement Retainers

FasDrill Bridge plug is similar to the conventional permanent bridge plug. The main difference is the composition of the material. It is made up of composite material with minimal ferrous metal content which makes it easier to drill the plug.

During drilling a well, drilling fluid solids tend to invade the near wellbore region causing the change in the permeability of the near wellbore zone. This relative change in permeability is referred to as formation damage or skin damage. Formation damage affects the productivity of the well.

Flaring is an important safety process in refineries, petrochemical facilities, upstream drilling and production facilities. Flaring is used for safely burning excess hydrocarbon gases which cannot be recovered. Flaring process avoids releasing hydrocarbon gases in to atmosphere. However the process generates smoke. In environmentally sensitive area or offshore rigs the smoke and possibility of liquid unburnt oil fall out could result in air and water pollution. High efficiency burners are used to minimize possibilities of environmental impact of flaring.

Oils with high viscosity and high specific gravity are called heavy oil. API defines oils of gravity below 22.3 deg API as heavy oil.

ICD is an abbreviation for 'Inflow Control Device'. In a lateral where multiple zones are open, it is possible for a high pressure zone to overpower the production flow with very little contribution from low pressure formation. This could deplete the high pressure zone faster and can result in water or gas breakthrough in the well. ICDs are used to balance the hydrocarbon flow from different formations thus helping reservoir and production optimization. In injector wells, ICDs are also used to balance injection pressure across different zones thus improving the production and recovery.

Inflow Control Devices

Isolator is a Halliburton Retrievable Bridge Plug with slips. It is mostly used for temporary abandonment, zonal isolation or with retrievable packer for pressure testing.

PCP is an abbreviation of 'Progressive Cavity Pump'. This is used for artificially lifting a well where reservoir does not have enough energy to flow naturally. PCP creates negative pressure forcing the fluid to move up. PCP has found to be useful for extracting high viscosity crude oil. PCPs do not perform well in deeper and deviated wells.

Packers have rubber or metal elements which provide mechanical barrier in the well. Depending on well design, testing or production requirement, a packer can be used to isolate a reservoir, open hole, a high pressure zone, casing leak, liner lap leak or to anchor tubing etc. Packers are classified based on temperature rating, differential pressure rating, setting and retrieving mechanisms, packing element, gripping mechanism, fluid environment etc. Various types and designs of packers are available with different companies and the selection is done based on specific conditions and requirements.

Packers

PBR (Polished Bore Receptacle) also known as Seal Bore is designed to accept the seal assembly. PBRs have varied applications in liner top, permanent packer or completion string for landing a production tubing seal assembly or tie back string. This design provides the benefit of achieving containment of flow within the tubing without any leak and allowing tubing movement due to thermal expansion.

PBR assembly works as an expansion joint when extreme tubing movements are expected and can also be used as separation tool, facilitating removal of production tubing. Length of PBR depends of application requirement. PBRs allowing even 30 ft stroke are available. PBRs are manufactured of high quality material with tight tolerance and are polished before running seal assembly in the receptacle.

As the name suggests, permanent packers are used for longer term or permanent installations in a well either to isolate the wellbore or tubing to casing annulus. Permanent packers can be removed only through milling. They have higher differential and temperature rating than retrievable packers. Permanent packers are also simpler in design since they do not require retrieval mechanism.

PVT is the abbreviation of Pressure, Volume, Temperature. PVT Sampling is the process of collecting reservoir fluid samples for laboratory PVT analysis. The samples are collected at appropriate location downhole or on surface where the samples represent the system in the reservoir.

PVT Sampling Methods

The retrievable packers are used for achieving temporary isolation for performing intervention activities. They are available in different differential pressure and temperature ratings, but are normally used for less severe well conditions. Retrievable packers are available with different setting mechanism like mechanical set or hydrostatic set options. Similarly, the release options could be either pull to release, cut to release etc. Retrievable packers offer flexibility and cost benefit in cases where removal is anticipated in the short term, or require repeated setting and unsetting or packer. Retrievable packers have more complex design than permanent packers due to setting and retrieving mechanism built inside the packer.

RTTS is a Halliburton retrievable packer with hold-down slips. RTTS packer is used for carrying out positive & negative pressure testing, treating, and squeeze cement operations. It is normally run with a circulating valve, which can be opened by straight pull as required. A safety joint is run above the tool to enable releasing of the work string in case the packer gets stuck during the operation.

Negative Pressure Test

Sand screens are required for providing sand controls while producing from unconsolidated formations. Sand screens help optimize production, provide wellbore stability and minimize equipment erosion by limiting sand from the formation. Sand screens are classified based on technology, construction, and mesh size. Appropriate sand screens are deployed in the production string depending on well conditions to achieve the best results.

Wiremesh Screens

SCRAMS (Surface Controlled Reservoir Analysis and Management System) is Halliburton's data acquisition and communication system for smart wells.

Seal Bore also known as PBR (Polished Bore Receptacle) is designed to accept the seal assembly. Seal bores have varied applications in liner top, permanent packer or completion string for landing a production tubing seal assembly or tie back string. This design provides the benefit of achieving containment of flow within the tubing without any leak and allowing tubing movement due to thermal expansion.

It works as an expansion joint when extreme tubing movements are expected and can also be used as separation tool, facilitating removal of production tubing. Length of seal bore assembly depends of application requirement. Seal bores allowing even 30 ft stroke are available. Seal bores are manufactured of high quality material with tight tolerance and are polished before running seal assembly in the receptacle.

A Smart Well completion is a system of collecting, transmitting and analyzing completion, production and reservoir data. It also allows selective zonal control to optimize the well production.

Sucker Rod Pumps are artificial lift method very commonly used for wells where reservoir does not have enough energy to flow naturally. The system broadly consists of a down hole pump plunger and valve assembly. The pump is powered by beam and crank assembly at surface. These are used for land wells and application becomes limited with deeper wells.

SenTREE is Schaumberg's test tree system to be used with subsea wellheads for deepwater wells. It consists of several different components and is used for Well Testing or Well Clean up operation in deepwater wells drilled by either a semi-submersible rig or a drill ship.

Shear Sub is a sub that is usually part of test tree assembly used for subsea wellheads. The string is spaced out to position the shear sub across share ram. In critical situation needing an emergency disconnect, shear ram will be activated to shear the DST string from shear sub. The sheared string can be retrieved with the help of an overshot and latch assembly later.

TCP is the abbreviation of 'Tubing Conveyed Perforation'. It's the process of running perforating guns on tubing, drill pipe, or coil tubing for perforating a required section of the well. Guns can also be run on wireline, but have limited application to low inclination wells. TCP is well suited for perforating vertical, highly deviated, or horizontal wells. It also facilitates underbalanced perforations, which limit the formation damage. TCP guns can be dropped in the well if there is enough rat hole. They can also be left attached to the tubing string and can be recovered later when pulling the tubular out of the well.

Tree Saver Sub, also known as Wellhead Isolation Tool (WIT) is used for isolating and avoiding exposure of wellhead to the treating fluid and pressures. The tool is inserted through the tree & wellhead bore through the tubing hanger into the tubing. It has a seal that seals in the tubing avoiding the wellhead exposure to the treating fluid and pressures.

Tubing is broadly referred to as the conduit that is run inside the casing or open hole in a wellbore. Tubing is used as a flow path for the formation fluid to flow from the reservoir to the surface or for pumping fluid downhole. The term is mainly used for the tubulars that are used for well testing or well completion after drilling a well. Tubing should be able to withstand burst, collapse, tensile, compressive, and tri-axial loads during all operations. They should also have the material properties to handle the corrosivity of fluid in a wellbore or formation. Tubing is designed to meet all stresses and conditions in routine well operations and also to specific requirements of special operations.

Wellhead Isolation Tool (WIT) also known as Tree Saver Sub is used for isolating and avoiding exposure of wellhead to the treating fluid and pressures. The tool is inserted through the tree & wellhead bore through the tubing hanger into the tubing. It has a seal that seals in the tubing avoiding the wellhead exposure to the treating fluid and pressures.

Well testing is the process of acquiring reservoir data and formation fluid properties after drilling the well to the planned target reservoir. The acquisition of data helps in analyzing reservoir characteristics and skin damage during drilling or other operations carried out in the well. The reservoir modelling carried out based on collected data is used for devising completion, stimulation and field development strategies to optimize reservoir production. It also helps in determining production potential of the well for investment decisions.

There are several ways to test a well. A wireline formation tester can be run in the well for capturing samples and measuring properties downhole. A Drill Stem Test (DST) can be carried out in cased hole or open hole for collecting samples and acquiring data by flowing the well to surface. A set of tools are used in downhole test string and equipment are rigged up on surface to safely flow and flare on surface.

After the initial flow for well cleanup, the flow is redirected to a test separator where formation fluids are separated into oil, gas and water phases. Any debris, sand or other material are removed for measurements and collection of samples after stabilized flow is achieved.

Completion is the process of making the well ready for production or injection. Types of completion vary significantly depending on the objectives, reservoir, reservoir fluid properties, reservoir potentials etc.

Types of Completions