Simultaneous Operation (SIMOP)
Simultaneous operation (SIMOP), in oil and gas drilling, production, and facilities management, refers to the conduct of two or more potentially hazardous operations at the same time on the same facility, well site, or adjacent area, where each individual operation would be acceptable in isolation but whose combination creates additional hazard potential through interaction of ignition sources, structural loading, personnel crowding, emergency response conflicts, or communication failures that would not exist if the operations were conducted separately; SIMOPs are a fundamental feature of modern offshore platform operations (where drilling, production, maintenance, and crane lifts occur simultaneously on the same structure), of onshore pad drilling (where multiple rigs drill adjacent wells while early completions or production occurs on already-drilled wells), and of any well intervention, workover, or completion activity performed on a live production platform or adjacent to a producing well; SIMOP management requires systematic hazard identification (identifying which combinations of activities create unacceptable risk), formal risk assessment (quantifying or qualitatively evaluating the combined risk), permit-to-work (PTW) integration (ensuring hot work, cold work, confined space entry, and other permits account for simultaneous activities), and a defined approval and communication structure (a SIMOP matrix or SIMOP coordinator function) that ensures no pair of incompatible activities occurs without all parties being aware and controls being in place.
Key Takeaways
- The SIMOP matrix is the primary risk management tool for simultaneous operations: a matrix listing all planned activities on one axis and all other possible simultaneous activities on the other axis, with each cell coded green (compatible, no additional controls required), yellow (compatible with specified additional controls and notification requirements), or red (incompatible, must not be conducted simultaneously under any circumstances); typical red cells include hot work (welding, grinding, cutting) within a defined exclusion zone around any open hydrocarbons, crane lifts over live production equipment where a dropped object could cause a release, energization of electrical systems in areas where other personnel are working with live hydrocarbons, and concurrent jetting or high-pressure operations in areas shared by other personnel; yellow cells require additional authorization (typically from an OIM or area authority), a detailed job safety analysis (JSA) for the combined activity, additional monitoring (gas detector placement, standby personnel), and a defined communication protocol (radio channel, check-in intervals) between the supervisors of both activities; the SIMOP matrix is a living document that must be updated when new activities are planned and reviewed at the start of each shift to ensure all concurrent activities are accounted for.
- Offshore platform drilling SIMOPs are among the most complex SIMOP management scenarios in the industry because the drilling rig is located above or adjacent to live production equipment on the same structure, and virtually every major drilling activity creates hazardous interaction potential: drilling with oil-based mud risks hydrocarbon vapors reaching the production module where ignition sources may exist; tripping pipe with gas kicks risk creates simultaneous blowout and production module explosion hazard; cement mixing and pumping requires heavy crane lifts over production pipework; wireline operations require pressured wellbore access adjacent to occupied production areas; the regulatory frameworks for offshore SIMOP management (UK PFEER Regulations, Norwegian NORSOK standards, US BSEE regulations) require operators to conduct formal simultaneous operations hazard studies (SIMOPS HAZOPs or HAZID reviews) before any new drilling campaign begins on an existing production facility, documenting the accepted risk basis for the combined operations.
- Onshore pad drilling SIMOPs arise from the practice of drilling and completing multiple wells from a single well pad simultaneously, which maximizes equipment utilization but creates hazardous interactions between drilling, hydraulic fracturing, and production operations on the same pad at the same time: the combination most commonly requiring SIMOP management is fracturing a recently drilled well while an adjacent well is being drilled (the frac fluid at high pressure could communicate through the formation to the open drilling borehole in a "frac hit," creating a sudden uncontrolled fluid influx in the drilling well), or fracturing a new well while a producing well on the same pad is flowing (the frac-induced pressure surge could exceed the producing wellhead or flowline pressure rating); SIMOP controls for onshore pad operations typically include minimum separation distances between wells being fractured and wells being drilled simultaneously, temporary isolation of producing wells during nearby fracturing operations (shut-in or shut-in with pressure monitoring), and communication protocols between the fracturing company and the drilling contractor.
- Permit-to-work (PTW) integration is the operational mechanism through which SIMOP controls are implemented in day-to-day facility management: each hazardous activity requires an approved PTW that specifies the work scope, the hazards identified, the controls required, the isolation verifications needed, and the personnel authorized to perform the work; when multiple permits are active simultaneously, the PTW system must flag potential conflicts (two permits affecting the same equipment, a hot work permit active in an area where an adjacent permit involves hydrocarbon work, a simultaneous lifting permit and a personnel entry permit in the same area) and require SIMOP review before approval; modern electronic PTW systems (SAP PM, Enablon, Intelex) have SIMOP conflict detection built into the approval workflow, flagging concurrent permits that share equipment tags, physical locations, or hazard categories and routing them to the designated SIMOP coordinator for compatibility review before both are approved; the PTW system is where SIMOP policy translates into daily operational decisions, and gaps in PTW integration are the most common root cause finding in post-incident investigations of SIMOP-related accidents.
- Emergency response conflicts are a frequently overlooked category of SIMOP risk: even if two operations are individually safe to conduct simultaneously from a normal-operations hazard perspective, their combination may render the facility unable to respond effectively to an emergency involving either operation; examples include simultaneous crane operations on both sides of a platform limiting the helicopter approach corridor used for medical evacuation, multiple operations requiring lockout-tagout of the same fire suppression systems, personnel from two simultaneous operations sharing the same muster station location creating confusion in an emergency headcount, or the noise and vibration from one operation (percussive demolition, for example) masking the acoustic alarm signals relied upon by the adjacent simultaneous operation; the SIMOP risk assessment must include scenario analysis of emergency responses (well blowout during simultaneous hot work, structural fire during simultaneous crane lift, personnel overboard during simultaneous confined space entry) to verify that emergency response capability is not degraded by the combination of activities even if each is individually acceptable.
Fast Facts
The Piper Alpha disaster in 1988, in which 167 people died on an offshore production platform in the North Sea, is the defining case study in SIMOP management failure in the oil and gas industry. The accident began when a condensate pump that was under maintenance (with its permit-to-work in the control room) was started by operators on a different shift who were unaware of the concurrent maintenance activity, because the permit had not been properly communicated between shifts. The Cullen Inquiry that followed mandated permit-to-work reform across the UK North Sea and effectively established modern SIMOP management as a non-negotiable safety requirement for offshore operations. The lessons of Piper Alpha are embedded in every contemporary offshore SIMOP standard, PTW system design, and shift handover procedure in the global offshore industry.
What Is a Simultaneous Operation (SIMOP)?
A SIMOP is any situation where two or more hazardous activities happen at the same time in a shared space or on a shared facility. On an offshore platform, that might mean the drilling rig is running casing over the production deck while a maintenance crew is doing hot work in the electrical room and a crane is lifting a generator over the wellbay. Each activity alone would pass a risk assessment. Together, they create combinations: the crane drop could hit the hot work area where sparks are present and fuel is nearby; the hot work could ignite vapors from a drilling mud spill; the drilling crew and the maintenance crew are both relying on the same muster area and the same radio channel in an emergency. SIMOP management is the discipline of identifying these combinations before they happen, deciding which are acceptable with controls and which are not acceptable under any circumstances, and then maintaining the awareness and communication throughout the workday to ensure the controls are actually in place when the activities coincide. It is fundamentally a coordination problem as much as a technical safety problem, which is why the human elements of PTW systems, shift handovers, and SIMOP coordinator roles are at least as important as the physical controls.
Synonyms and Related Terminology
Simultaneous operation is also written as SIMOPS (plural, used when referring to the management program or the set of concurrent operations collectively). Related terms include permit-to-work (the formal authorization system that controls access to hazardous work on a facility, the primary mechanism through which SIMOP controls are applied to individual operations by flagging and resolving conflicts between concurrent permits before both are approved), dropped object (a specific SIMOP hazard category where crane lifts or elevated work tasks create the risk of objects falling onto personnel or equipment in the simultaneous operation below, managed through exclusion zones and lift plans that account for all concurrent activities beneath the crane path), hot work (any work involving ignition sources including welding, cutting, grinding, or open flames, the SIMOP category most strictly controlled because its combination with any simultaneous hydrocarbon release or open-top tank work creates an immediate explosion and fire risk regardless of the spatial separation between the two activities), frac hit (the pressure communication from hydraulic fracturing of one well into an adjacent wellbore, the primary SIMOP hazard in onshore pad drilling where fracturing and drilling or production operations occur simultaneously on the same pad), and job safety analysis (the step-by-step task breakdown and hazard identification conducted before each SIMOP activity, used to identify the specific controls and notifications required when that task is conducted simultaneously with the other concurrent activities on the facility).
Why SIMOP Management Is the Difference Between Efficient Operations and Catastrophic Loss
The pressure to conduct simultaneous operations is commercial: every day a drilling rig sits idle on a production platform waiting for maintenance to finish is a day of rig costs with no drilling progress. Every day a producing well is shut in to allow safe completion of an adjacent well is revenue foregone. SIMOPs exist because operators have decided that the efficiency gain of concurrent operations outweighs the incremental risk, provided that risk is properly managed. That judgment is valid when the SIMOP management system is functioning as designed, when the PTW system flags conflicts and routes them to someone with authority to resolve them, when the SIMOP coordinator has real-time visibility of all concurrent activities, when every supervisor on the facility knows what everyone else is doing and what the stop-work triggers are. It fails when the PTW system is a paper formality, when no one has authority or attention to resolve permit conflicts, when shift handovers omit concurrent activities, when the pressure to maintain schedule overrides the discomfort of raising a SIMOP concern. Piper Alpha was a SIMOP failure. Texas City was a SIMOP failure. The root cause in both cases was not ignorance of the hazard but the organizational conditions that allowed the hazard to go unmanaged. Rigorous SIMOP governance is the difference between those outcomes and the efficiently run, incident-free operations that most platforms achieve most of the time.