Page 96 - Intelligent Digital Oil And Gas Fields

Instrumentation and Measurement 65

flow-line pressures and at least flow-line temperature instruments. It is also
very common for these wells to support automatic valves including wellhead
chokes. The automatic remote-activated chokes facilitate supervisory con-
trol and optimization. Multiple operators use the automated chokes for
intermittent well control or for automated curtailment and restart of wells,
to balance production with facility constraints, such as when a compressor
goes down.
As unconventional wells progress through their life cycles, they move
onto artificial lift. Gas lift, plunger lift, rod pumps, and some ESPs are used.
All of these are being installed with local-control elements that can be
remotely operated. Operators commonly have the ability to set gas lift rates,
pump speeds, or pump-off controls from field collaboration centers, without
going to the well site. Real-time data-capture technology (e.g., a product
from OSI called PI, one of the data historian software available in the mar-
ket) can be used stand-alone or integrated with SCADA systems to control,
analyze, and optimize multiple lift types. As stated above, unconventional
assets rely heavily on data-driven workflows because traditional modeling
tools do not fully apply. As these are usually high well-count assets, there
are large volumes of data to analyze. SCADA and historian systems are
now embedding predictive analytics tools into their platforms. Additionally,
OSI’s PI application framework translates the traditional SCADA/DCS tag-
based data model into a virtual one so that users can get right to the data they
need with logical names instead of tag names. These systems, with their
added security and robustness, give more power to the process control net-
work and operations staff, instead of moving that processing into the enter-
prise IT architecture.

2.3 DATA GATHERING AND SCADA ARCHITECTURE

2.3.1 Well-Location Data Gathering and Telemetry
The two main ways to gather and communicate data are wired and wireless.
Localized well and control facilities, such as offshore platforms, typically use
a wired structure. Scattered, large well-count assets, like the unconventional
ones, generally used a wireless strategy. Fig. 2.12 shows a well location with
an RTU controller, wireless equipment, and an Ethernet switchboard.
The main issue for DOF systems is that larger volumes and increased
frequency of data needs to be gathered and transferred to the control loca-
tion. For medium-sized offshore and land-based assets, these requirements