Page 327 - Hydrocarbon Exploration and Production Second Edition

314 Production Operations Input to the FDP

Risk analysis techniques may be used to help in this decision, and if SIPROD is
adopted, then procedures will be written specifying how to operate in this mode.
It is common practice in production operations to close in production from a well
when another nearby operation is rigging up or rigging down, to avoid the more
serious consequences of a load being dropped during equipment movements.
Another more general term used is SIMOPS.
Monitoring and control of the production process will be performed by a
combination of instrumentation and control equipment plus manual involvement.
The level of sophistication of the systems can vary considerably. For example,
monitoring well performance can be done in a simple fashion by sending an
operator to write down and report the tubing head pressures of producing wells on
a daily basis, or at the other extreme, by using CAO. This uses a remote computer-
based system to record and control production on a well by well basis with no
physical presence at the wellhead.
CAO involves the use of computer technology to support operations, with
functions ranging from collection of data using simple calculators and PCs to
integrated computer networks for automatic operation of a field. In the extreme
case, CAO can be used for totally unmanned offshore production operations
with remote monitoring and control from shore-based locations. In considering
the requirements for operations at FDP stage, the inclusion of CAO would have a
great impact on the mode of operations. CAO may also be applied to reporting,
design and simulation of possible situations, leading to performance optimisation,
improved safety and better environmental protection.
By providing more accurate monitoring and control of the production
operations, CAO is proven to provide benefits such as
increased production rates: through controlling the system to produce closer to its
design limits, reducing downtime and giving early notice of problems
reduced OPEX: less manpower costs, reduced maintenance costs due to better
surveillance and faster response and reduced fuel costs
reduced CAPEX: by increasing throughput, less facilities capacity required, less
accommodation and office space and reduced instrumentation
increased safety: less people in hazardous areas, less driving, better monitoring of
toxic gases and better alarm systems
improved environmental protection: control of effluent streams and better leak detection
improved database: more and better organised historical data, simulation capability,
better reporting and use as training for operators.
The cost of implementing CAO depends of course on the system installed, but
for a new field development is likely to be in the order of 1–5% of the project
CAPEX, plus 1–5% of the annual OPEX.
An example of an application of CAO is its use in optimising the distribution of
gas in a gas-lift system (Figure 12.2). Each well will have a particular optimum GLR,
which would maximise the oil production from that well. A CAO system may be
used to determine the optimum distribution of a fixed amount of compressed gas
between the gas-lifted wells, with the objective of maximising the overall oil
production from the field. Measurement of the production rate of each well and its