Gas Lift Chapter 2 Advantages and Limitations

The flexibility of gas lift in terms of production rates and depth of lift cannot be matched by other methods of artificial lift if adequate injection-gas pressure and volume are available. Gas lift is one of the most forgiving forms of artificial lift, since a poorly designed installation will normally gas lift some fluid. Many efficient gas lift installations with wire line-retrievable gas lite valve mandrels are designed with minimal well information for locating the mandrel depths on initial well completion. Technical Data used in the field explained in petroleum courses in Rawalpindi.

Highly deviated wells that produce sand and have a high formation gas/liquid ratio arc excellent candidates for gas lift when artificial lift is needed. Many gas lift installations are designed to increase the daily production from flowing wells. No other method is as ideally suited for through-flow line (TFL) ocean floor completions as a gas lift system. Maximum production is possible by gas lift from a well with small casing and high deliverability. Wire line-retrievable gas lift valves can be replaced without killing a well or pulling the tubing. Some more details of petroleum courses in rawalpindi are as under.

The gas lift valve is a simple device with few moving parts. and sand laden well fluids do not have to pass through the valve  to be lifted. The individual well in-hole equipment is relatively inexpensive. The surface equipment for injection gas control is simple and requires little maintenance and practically no space for installation. The reported overall reliability and operating costs for a gas lift system are lower than for other methods of lift. The primary limitations for gas lift operations are the lack of formation gas or of an outside source of gas, wide well spacing. and available space for compressors on offshore platforms. Generally, gas lift is not applicable to single-well installations and widely spaced wells that are not suited for a centrally located power system. Gas lift can intensify the problems associated with production of a viscous crude. a super-saturated brine. or an emulsion. Old casing. sour gas. and long. small-ID flow lines can rule out pas lift operations. Wet gas without dehydration will reduce the reliability of gas lift operations. TSK Training for Skills and Knowledge is the best institute in Rawalpindi Islamabad for Pakistani Students who wants to join oil petroleum courses in Rawalpindi.

Chapter 5 Gas Lift

Gas lift is the method of artificial lift that uses an cxternal source of high-pressure gas for supplementing fort nation gas to lift the well fluids. The primary consideration in the selection of a gas-lift system to lift a well.  a group of wells. or an entire field is the availability and compression cost of gas. Technical Data about this  field explained in petroleum courses in Rawalpindi.

Continuous-ilow gas lift is the only method of artificial lift that fully utilizes the energy in the formation gas production. Most wells are gas lifted by continuous flow, which can be considered an extension of natural flow by supplementing the formation gas with additional high-pressure gas from an outside source. Gas is injected continuously into the production conduit at a maximum depth on the basis of the available injection gas pressure. The injection gas mixes with the produced well fluids and decreases the flowing pressure gradient of the mixture from the point of gas injection to the surface. The lower bowing pressure gradient reduces the flowing bottom hole pressure (BHFP) to establish the drawdown required for attaining a design production rate from the well. If sufficient drawdown in the bottom hole pressure (BHP) is not possible by continuous flow, intermittent gas lift operation may be used. Some more details about this field  of petroleum courses in rawalpindi are as under.

Intermittent gas lift requires high instantaneous gas volumes to displace liquid slugs to the surface. The  disadvantage of intermittent lift is an “on-off” need for high-pressure gas. which presents a gas handling problem at the surface and surging in the BHFP that cannot be tolerated in many wells producing sand. Most hiph-pressure gas lift systems are designed to recirculate the lift gas. The low-pressure gas from the production separator is compressed and injected into the well to lift the fluids from the well. This closed loop. As illustrated in Fi?. 5 1 ,, is referred to as a closed relative gas-lift system. Contmuous-flow gas lift operations arc preferable with a closed relative system. Intermittent gas lift operations are particularly difficult to regulate and to operate efficiently in smaller closed relative systems with limited gas storage capacities in the low- and high-pressure lines.

Applications:

Gas lift is particularly applicable for lifting wells where high-pressure gas is available. Gas compressors may have been installed for gas injection, or high-pressure gas wells may be nearby. Since the cost of compression far exceeds the cost of down hole gas lift equipment, gas lift always should be considered when an adequate volume of high-pressure gas is available for wells requiring artificial lift. Most wells can be depleted by gas lift. which is particularly true since the implementation of reservoir pressure maintenance programs in most major oil fields. TSK is the best institute in Rawalpindi Islamabad for  Pakistani Students who wants to join petroleum courses in Rawalpindi.

Tubing/Packer System

a suitably selected packer by using also operations efficient. Wireline pressure and logging operations go faster and smoother. Longer fliess life will be achieved with the use of a packer through the optimal use of gas energy. Technical Data about in this  field explained in petroleum courses in Rawalpindi.

Carry out the use of a packer in a gas well with a tail pipe with the perforations, will alleviate the problem of gas sources headline, with water loading and die prematurely. (The water is continuously generated as a mist and is not allowed to build up over the perforations.) This use of a packer and tailpipe will not control the natural water flow, but will keep the water along to disposal at the time transportable pressure is less than the pressure required to flow. Some more details of petroleum courses in rawalpindi are as under.

Where Packers are not used:

Packers are not in rod-pumped wells, unless exceptional circumstances such as Dual final call for a run. Electric submersible pumped wells would have no Packer, except when used with uphold subsurface safety valves by government safety regulations for offshore wells required. Many naturally flowing, high-volume, Sweet Crude Wells are the ring without Packer produces up; to be good and to kill (circulate) or for the execution of specific protocols or gauge a small tubing runs. Dry, sweet gas wells often produce up both the tubes and the ring and have no packer.

Well Operational modes:

There are four operating modes, which each could well occur where: (1) shut-in; (2) Preparation of (either liquid, gas or a combination); (3) injection (hot or cold liquids or gases); or (4) treating (high, low or medium pressures and volumes).

The usual mode of operation is only one of the factors that must be considered when a particular type of packer selection are well used in a. Subsequent operations and its pressure and temperature changes are likely to be extremely important to be successful utilization Packer. Typical 2,3-temperature vs. depth profiles are shown in FIG. 4.9. These profiles are similar to those measured in wells in one of four modes: shut-in, production, injection or treatment. Coward. 4.9a shows a typical geothermal gradient, with the temperature with the depth of the bottom hole temperature increases (BHT). Every time a well closed in, the operating temperature profile will begin towards the shape of the natural geothermal profile move. The production and temperature profiles for gas and oil, are shown in Figs. 4.9b. The wellhead temperature of an oil well is a little less than BHT. The amount of as a crude cooling flows at the surface depends on several factors: (1) the relative amount of oil and water, (2) the specific heat of the oil and water, (3) the flow velocity, (4) the gas / liquid ratio, and (5) of the vertical flow pressure drop, the gas freed controls and related cooling effect. The temperature profile of a gas well may have a wellhead temperature lower than the ambient temperature. In any case, the temperature of a gas well wellhead on the BHT will depend on the flow velocity, the pressure drop in the pipeline, the specific heat of the gas, and other factors. TSK Training for Skills and Knowledge is the best institute in Rawalpindi Islamabad for  Pakistani Students who wants to join oil field after petroleum courses in Rawalpindi.

Considerations For Packer Selection

Packer selection requires an analysis of the compressor goals operations as a good beginning ends expected stimulating the production methods and work. Technical Data used in the field explained in petroleum courses in rawalpindi.

Since both good current and future conditions of the package with a minimum total cost
must achieve the objectives are selected. The first investment and installation costs should not be the sole criterion. The total cost Packer is not only directly in an irreversible dissociation and failure, but in many shapes, such as damage during the subsequent formation and corkscrew together or exchange tube operating factors. Some more information about this field  petroleum courses in rawalpindi are as under.

Uncollectible will be improved significantly by oil or water-free solid instead of mud liquid packaging. The frequency of errors can be minimized by suitable Packer Packer for the welfare state and expect the future conditions when the packer is set. Duration Packers are by far the most reliable and if for differences imposed suitable high pressure shall appropriately mounted during stimulation and adjusted. They are widely used, when reservoir pressures vary significantly in the different accounts between the zones. Weight in September types of successful retrievable packer voltage only in one direction when the motor running at the packer and is not an exaggeration.

Coordination of the surface / Rigs:
Packer setting always requires a surface effect and most cases either the vertical or rotational movement of the tube. The selection of the packager must be connected appliances wellhead. Well completion should be a coordinated operation are contemplated. The surface and downhole equipment They should work together with a secure fit on a system to ensure selected function. This is especially in high pressure applications.

Mechanical packer:
The end result of most packer setting mechanism is a cone behind a conical driving of the suspension in the housing wall and preventing the sliding force to compress packer movement and to provide a filler a sealing effect. Although the end result is relatively simple, the means for changing and the subsequent recovery of packers achieve significantly between different types of packers. Some packers two or more round trip, requiring a fixed time, and some eliminate trips hydraulic setting. Over time, the cost should be carefully considered, use mainly in deep wells with high cost of drilling equipment. In some cases, the higher cost may be more than Packer by saving time offset, in particular offshore structures. TSK Training for Skills and Knowledge is the best institute in Rawalpindi Islamabad for  Pakistani Students who wants to join oil field after petroleum courses in rawalpindi.

Packer Utilization And Constraints

The uses and limitations of different types of packers, the factors taken into account understanding before selecting the best compression program and show to explain how to achieve certain goals.
Fixed head compression packer: Technical Data used in the field explained in petroleum courses in Rawalpindi.
recoverable compression (weight set hard head) baggers are applied when the pressure above the packer pressure ring exceeds below the packer, as. in a production well with a complete ring This situation involves lifting gas. Fig. 4.1 shows this kind of Packers. '
The boundaries of a compression packer fixed head are:
1. Packer release may be hampered by the high differential pressure across Packer.
2. Packer can, if a change in operationalmode results (abbreviated tube) in a temperature decrease of the suspended tube.
3. The tubes can permanently corkscrew, when a change in the mode leads to an increased tube temperature (extended tube). Some more details of petroleum courses in rawalpindi are as under.
Fixed head voltage Packer:
is packagers Spann achievable generally be used when the pressure below the packer is greater than the annulus pressure across the plug, it is for example in an injection well or a low pressure and volume in flat recesses put these treatments used packers in which the weight of the pipe does not enough compression
Packer properly. Limitations of voltage recoverable packers are hardheaded:
1. Loosen is difficult, with high pressure differential across the packer.
2. The tubes could mode of operation leads to a reduction of the temperature, when a change separated.
3. Packer might be released when a change in the mode of operation leads to an increase in temperature.
Packager is used when two fixed mechanically settle simultaneously. Requires Armor pipe back depth including tubes connected to use the weight of the blade pins that hold the disarmed Packer mode. It can isolate a damaged or old perforations in the casing area temporarily used. This compression program is for temporary use and should be as fast as their purpose is achieved recovered.
Control printhead Packer:
The control head retrievable packer compression (Fig. 4.4) a bypass valve to relieve the problem of liberation canner by excessive differential pressure. The valve is on top of the packer. Opens the pressure equalization through the packer, through the hose without mobile reception
Packer. As with the compression utility hard head, used to weight hoses applied this packer pressure from above. Not suitable for the treatment of injection wells or low volume and pressure. The limitations are:
 (1) the bypass valve or compensation can be opened when a mode change process leads to a hose,
decreasing temperature and
(2) could the hose permanently corkscrew when a mode change to a hose leading
Increasing the temperature. TSK Training for Skills and Knowledge is the best institute in Rawalpindi Islamabad for  Pakistani Students who wants to join oil field after petroleum courses in Rawalpindi.