Simultaneous operations on pads, plants and pipelines

Simultaneous operations, usually shortened to SIMOPS, happen whenever two or more activities in the same area could affect each other: a crane lift over a pipe rack while a line is opened below, hot work upwind of a tank being gauged, or a frac fleet pumping next to producing wells. HSE-221 explained the general tools for managing SIMOPS: conflict matrices, coordination meetings, permit boards and distance rules. This lesson applies them to the situations that make SIMOPS a daily reality in oil and gas: multi-well pads where drilling, completions and production share one lease, plants where construction ties into live equipment, and pipelines where crews work far from the control room that can change the line's pressure.

Why oil and gas sites are full of SIMOPS

Modern oil and gas development puts many activities close together. A pad in the Montney or the Bakken may have producing wells, a rig drilling new wells a few meters away, a frac fleet completing other wells, flowback equipment, a battery, trucks hauling water and sand, and construction crews building facilities, all within a few hundred meters. Each activity is run by a different contractor with its own procedures. Gas plants and compressor stations run turnarounds and expansions while the rest of the facility keeps producing. Pipelines are worked on while connected to live systems. In all of these, the hazards of one activity become the hazards of the others.

Typical oil and gas SIMOPS

Frac hits and offset wells

When a well is hydraulically fractured, fractures can grow toward nearby wells and connect with them. Pressure and fluid from the frac can then reach the offset well, sometimes far above that well's normal operating pressure. Frac hits have damaged wellheads, flowlines and production equipment and caused releases at offset wells, and regulators and industry groups in both countries have issued guidance on managing the risk. Typical controls, set out in the operator's procedures and coordinated through the SIMOPS plan, are identifying offset wells within a set distance of each fracture stage, shutting them in or isolating them from low-rated surface equipment, confirming wellhead and flowline ratings, monitoring their casing and tubing pressures during the frac, agreeing communication between the frac crew and the production operator, and setting stop criteria if pressure rises at an offset well.

For example, a production operator at Pinecrest might shut in wells 1 to 8 and isolate them from the battery while Ridgeback Pressure Pumping fractures wells 9 to 12, and watch their wellhead pressures on the control system and by local gauge, with a direct radio line to the frac van. If any offset well's pressure rose by more than a set amount, the frac would stop until the cause was understood.

The SIMOPS plan

On a busy pad or during a turnaround, SIMOPS cannot be managed by each permit issuer noticing conflicts on the day. Operators prepare a SIMOPS plan, sometimes called a combined operations plan, before the activities start. It usually includes:

• a map of the site showing each activity's area, exclusion zones, traffic routes, muster points and wind direction indicators;
• a SIMOPS matrix listing which pairs of activities are allowed together, allowed with stated controls, or not allowed at the same time and place;
• a clear statement of who has overall authority on the site at each phase, often the operator's site supervisor or person in charge, and how that authority is shared with the drilling, completions and construction supervisors;
• interface agreements and bridging documents between the operator and each major contractor, as HSE-331 described;
• a daily coordination meeting, attended by every activity's supervisor, where the day's permits are reviewed together on a map or board;
• one emergency plan for the whole site: one alarm system with one meaning, one set of muster points, one headcount process and one incident commander.

Checking the day's work against the matrix

A SIMOPS matrix is only useful if it is checked every time the plan for the day changes. The program below holds a small, invented SIMOPS matrix for the Pinecrest pad and checks the activities planned for one day, area by area. Each pair of activities in the same or an adjoining area is looked up; the program reports pairs that are not allowed and the controls required for pairs allowed with conditions.

# Check a day's activities on a pad against a small SIMOPS matrix (invented rules).
from itertools import combinations
MATRIX = {  # frozenset pair -> ("ok" | "controls" | "no", note)
    frozenset({"frac pumping", "producing well work"}): ("no", "no well work on offset wells while pumping"),
    frozenset({"frac pumping", "crane lift"}): ("controls", "lift outside frac exclusion zone; frac van agrees"),
    frozenset({"hot work", "tank truck loading"}): ("no", "suspend loading or hot work"),
    frozenset({"hot work", "line opening"}): ("controls", "upwind only, continuous gas test, kept well apart"),
    frozenset({"crane lift", "line opening"}): ("controls", "no load over the open line"),
    frozenset({"wireline", "producing well work"}): ("controls", "shared alarm, shut-in criteria agreed"),
    frozenset({"hot work", "frac pumping"}): ("no", "no hot work in frac area while pumping"),
}
ADJOINING = {("battery", "pad east"), ("pad east", "pad middle"), ("pad middle", "pad west")}

plan = [  # (activity, area, time window)
    ("frac pumping", "pad west", (7, 19)),
    ("crane lift", "pad middle", (9, 11)),
    ("producing well work", "pad middle", (13, 16)),
    ("line opening", "battery", (8, 12)),
    ("hot work", "battery", (10, 15)),
    ("tank truck loading", "battery", (14, 15)),
]

def near(a, b):
    return a == b or (a, b) in ADJOINING or (b, a) in ADJOINING

def overlap(w1, w2):
    return max(w1[0], w2[0]) < min(w1[1], w2[1])

for (a1, z1, w1), (a2, z2, w2) in combinations(plan, 2):
    if not (near(z1, z2) and overlap(w1, w2)):
        continue
    rule, note = MATRIX.get(frozenset({a1, a2}), ("ok", ""))
    if rule != "ok":
        start, end = max(w1[0], w2[0]), min(w1[1], w2[1])
        print(f"{rule.upper():<8} {a1} + {a2} ({start}:00-{end}:00): {note}")

CONTROLS frac pumping + crane lift (9:00-11:00): lift outside frac exclusion zone; frac van agrees
NO       frac pumping + producing well work (13:00-16:00): no well work on offset wells while pumping
CONTROLS line opening + hot work (10:00-12:00): upwind only, continuous gas test, kept well apart
NO       hot work + tank truck loading (14:00-15:00): suspend loading or hot work

The check finds two pairs that cannot go ahead as planned. Producing well work in the center of the pad from 13:00 would overlap with frac pumping on the adjoining west side, which the matrix forbids, so that work must move to a day without pumping. Hot work at the battery overlaps with tank truck loading from 14:00 to 15:00, so one of them must be rescheduled. Two other pairs are allowed with controls, and those controls must appear on the permits concerned. The value of writing the matrix down is that the coordinator does not have to remember every rule under the pressure of the morning meeting.

Construction in operating facilities

Adding equipment to a live battery or plant brings construction crews, who may be used to greenfield sites, into an operating hazard area. The SIMOPS plan should set where construction ends and operations begins, which may be marked by fencing and a separate gate; require that construction crews working inside the operating area work under the operator's permit system; plan tie-ins into live systems as separate, carefully isolated jobs, often during a short outage; and control construction hazards such as excavation near buried live lines, crane lifts over live equipment and hot work near process equipment. Pre-commissioning and commissioning activities, when new equipment is first filled with hydrocarbons, are a high-risk interface and usually need their own SIMOPS review.

The control room in SIMOPS

Control rooms often see more of the site's activity than anyone in the field, and they can change conditions remotely: open a well, start a compressor, change a pipeline setpoint or reset a shutdown. In SIMOPS, the control room should attend or be briefed by the coordination meeting, show active permits and SIMOPS restrictions on its screens, agree before any remote action that affects an area with active work, and have a direct line to each activity supervisor. Pipeline control centers need the same discipline with field crews working on or near their lines, including agreed limits on pressure changes while crews are exposed.

Start-up, shutdown and abnormal conditions

Many SIMOPS incidents happen when the plant is not in its normal state: during start-up after a turnaround, during a shutdown, or during an upset. Operating crews are busy and conditions change quickly, and maintenance crews still on site may not know. Good practice is to restrict or suspend permitted work in affected areas during start-up and shutdown, to tell all crews before starting any non-routine operation, and to treat an upset as a reason to stop work and reassess, as covered in Lesson 11.