three situations that motivate the maximization of condensate recover are the
maximization the crude oil production when processing the associated gas and
the injected gas into the crude oil. Second is processing he retrograde
condensate gas, which is to recover the condensate and reinject the gas to the
reservoir for more oil recovery. Lastly, the natural gas liquid (NGL) that is
produced from condensate could be more valuable as a liquid than as gas
components, which it will better profit and revenue for the company.
Transportable gas is a gas that has
minimal processing in the field and transport through a pipeline to a final
processing plant. A salable gas is a gas hat requires all processing necessary
to meet any specification.
three alternatives procedures that can be adopted if condensates are present
are 1) no condensates removal and two-phase pipeline flow, 2) Condensate
removal to produce a hydrocarbon dew point less than the lowest expected temperature,
and 3) No condensate removal and instead have a dense phase transport.
LET stands for lowest expected temperature
in a pipeline. If the lowest expected temperature is higher than hydrate point
of gas then water removal my not be absolutely necessary. Gas may exhibit hydrocarbon
condensation in the pipeline if the gas has not be dehydrated to reduce the
water dew-point below the lowest expected temperature in the pipeline and if
the pipeline is exposed to low temperatures.
The six process modules that are commonly
used in field processing of natural gas are Phase Separation, Treating,
Compression, Dehydration, Condensate Recovery, and Recompression.
to Oil Field Processing of Petroleum, designing a facility cannot be done based
on the initial production condition because pressure and flow-rate changes will
affect selection and design of vessel and pipe sizes and of compressor horsepower
or even the necessity of compression. Designing a facility should be based on the
consideration of characteristics and capacities of a reservoir in early and
late life of the project.
Pressures and flow rates affects the
design of any equipment’s needed in a facility because we need to make sure
that the equipment’s can operate and function over a range of flow rates with
uncertain compositions, pressures, and temperature. Petroleum engineers
estimate the flowrates based on wells logs and reservoir simulations in a way
that they would be able to decide the amount of hydrocarbon present. According
to Petroleum Engineering Handbook, even if the estimates are good, the composition,
flowrates of oil, gas, and water, pressures, and temperatures change over the
life of the field as wells mature and new wells are dilled. The actual
production rate for a facility increase as the wells are completed up to the
design rate. This rate will be maintained as long as possibly drilling additional
wells; then, oil and gas rated will decline, while water rates will increase
and flowing pressure will decrease as the reservoir is depleted.
The three main objectives of gas
processing are to produce a transportable gas stream, to produce a salable gas
stream, and to maximize condensate production.
The maximum allowable concentration of
carbon dioxide (CO2) is between 2 and 4 percent, while for hydrogen sulfide
(H2S) is normally limited to ¼ grain per 100 standard cubic feet (scf) or 4 ppm
The common impurities that are found in
natural gas are carbon dioxide (CO2) and hydrogen sulfide (H2S) and nitrogen
(N2). Problem that are caused with these impurities are that H2S is very toxic,
while CO2 forms strong acid and having CO2 present could lead to corrosion in
the pipelines resulting in leaks or explosions. Also having nitrogen present
would lower the heating value of gas.
Heat exchangers are used to cool compressors
outlet gas streams. They are also used to cool gas, as well as liquids for
treating water from oil and regenerating glycol and other fluids used to treat
gas back to a lean state. Heat exchangers could also be used when dealing with
hot reservoirs, where fluids past the choke are over temperature.
The two processes that can be used to
stabilize the liquid from the initial separator are whether reducing the
pressure and let other lighter components flash by a multistage separations or
by a combination of pressure reduction and heating “condensate stabilization”.
remedy this problem, one can inject some solvents, such as antifreeze or
methanol to prevent liquids from freezing. Another method that could be done to
remedy this problem is apply low temperature exchange units and indirect fired
heaters can be used to prevent hydrates from plugging the choke.
If temperature becomes too low the problem
that occur with the manifest at choke is hydrates will form and there is a
possibility that liquids will turn in to condensate and hydrates will form. Also
if temperature becomes too low, pressure decreases which it will cause gas to
cool. These hydrates has many effects, which they can plug the choke and
flowlines and that would lead to impact the desired flow rates.
In marsh areas it is acceptable to install
facilities on wood, concrete, or steel platforms or on steel or concrete
barges. While facilities that are in shallow water can be installed in several
different platform connected by bridges and in deep water it may be necessary
to install all facilities and wells on the same platform. Lastly, facilities
must be enclosed that are in cold environment and maybe necessary to insulate
vessels and pipe and house all controls in a building attached to vessels to
prevents frozen valves.
There are many types of production
facilities and it would be difficult for one to classify it because they differ
due to production rates, fluid properties, sales, disposal requirements,
location, and operator preference.
to the Petroleum Engineering Handbook, auxiliary system are needed to support
the production facility are safety systems, including safety instruments, and
shutdown system; fire and gas detection; firefighting equipment. Other
equipment maybe needed depending on the location and complexity of the facility
and if personnel are included. Some
other facilities would require power generators and electrical systems, along
with auxiliary heating and cooling systems which are needed for the treatment
of oil and gases to power gas turbine generators and compressors.
A glycol gas dehydration is a system, is
water that is often removed from gas. This is done by adding some additives
such as triethylene glycol
to absorb water vapor from gas towers. The system of glycol gas dehydration has
different components such as glycol absorber, pump, surge tank, and reboiler.
Sour gas is when natural gas contains
Hydrogen Sulfide (H2S) and Sweet gas is when natural gas contains no (H2S) or
if the (H2S) has been removed. The process of removing the hydrogen sulfide and
possibly carbon dioxide (CO2) is referred to as ‘Sweeting”.
According to Petroleum Engineering Handbook,
BS&W stands for Basic Sediment and water. BS&W is the percent by volume
of water and other sediments in the oil; such as free water, sediments,
emulsion and is measure as a volume percentage of the production stream. Other
typical specifications in oil pipelines ranges from 0.1 to 3%, while it ranges
by a 1% volume for a place such at the Gulf of Mexico.
PSV stands for pressure safety valve. It
is mainly used to release gases from equipment to avoid over pressurization. It
is also designed to release pressure that MAWP is exceeded, if that MAWP
pressure exceeds the designed pressure, then the PSV takes stands. The PSV also
protect the equipment from getting damaged by over pressurization, eliminates
explosion that might occur or a fire and a serious injury.
5) MAWP stands for maximum allowed working pressure of the separator. MAWP
is a design pressure that is greater than the operating pressures to prevent
small fluctuations in the process from causing overpressure of the pressure
Salts in crude oil are normally produced
from water that is mixed with oil, although other salts may form due to
pressure and temperature changes because of tripping of water vapors as the
fluid flows up the wellbore and through the production unit and they are not
desirable in crude oil because it may cause a refining problem when the water
is boiled off in the refinery distillation unit. Also high water content can cause
corrosion problems worse in pipelines and other transportation system and can
cause problems with downstream processing.
3) According to Petroleum Engineering Handbook, there are multiple ways
where an oilfield is different than refinery or chemical plant. The process is
simpler in an oilfield facility, which consist of phase separation, temperature
and pressure changes, but there is no chemical reaction to make new molecules. Also
in an oilfield facility, the composition is usually estimated based on
drill-stream tests of exploration wells or from existing wells in the similar field
and the design flow rates are estimated from well logs and reservoir
simulations. While in a refinery or a chemical plant, the feed-stream flow rate
and composition are defined before the equipment is designed.
Flaring and venting of produced gas is not
largely used today because of emissions and due to availability of pipelines,
which all of the unused gas can be sold or reinjected back into the reservoir .
Gas that cannot be transported is usually compressed for reinjection into the
reservoir. Gas treating may involve only separation from the liquids, or it may
include additional processes such as compression, dehydration, removing H2S and
CO2 or gas processing to condense heavier components that can be transported as
The goal of a surface production facility
is a system which it is in charge of the separation of well stream fluids into
its single phase component (oil, gas, and water) and their transport and
processing in to marketable (in-spec) products or disposal in an
environmentally acceptable manner.
Homework #1, PNG 480
PSU ID: mfk5096
Name: Moustafa I Kotob