Liquid loading is one of the major challenges faced by shale gas producers. This phenomenon occurs when the gas in-situ velocity is insufficient to carry the produced liquid, leading to liquid fallback in the wellbore. Liquid Loading can occur during the flowback phase, the phase where the well is producing liquid from hydraulic fracturing, as well as the production phase, and is known to cause premature gas production decline, as shown in Figure 1, as well as production instability and flow assurance issues.
In Part 1 of this GATEKEEPER series on complexity, we identified 8 key sources of project and project team complexity. In Part 2, we discuss what can be done about them.
The discussion has to start with inherent project complexity, which includes technical complexity and non-technical, or social-political complexity. A structured approach is necessary to ensure completeness. Table 1 lists a few of the sources of technical complexity, and Table 2 lists a few of the sources of social-politicalcomplexity.
Over 80% of major projects fail badly on cost, and/or schedule and/or production rate (1). The average cost overrun is 33%; on a $4 billion project that is $1.5 billion. Schedule overruns and production impairments cost atleast that much again. Consequently, we are leaving billions of dollars on the table.
Why does this happen? One reason it happens is because major projects in the oil patch are now more complex than we are capable of effectively managing.
This GATEKEEPER discusses an effective subsea tree PWV (USV) leak test method. The test can be done quickly – entire test time is about 15 minutes, including the 5 minute monitoring time. More importantly, the test gives repeatable, unambiguous results that are easy to interpret and it can be done easily during any well shutdown.
A maintenance management system is a tool used for managing and controlling work, materials, and equipment throughout the oil and gas production chain, from offshore platforms to refineries and pumping stations. Many maintenance management systems are becoming computerized, allowing for a central storage location for the majority of the asset information and data. Computerization of the maintenance system allows users to have access from multiple locations and, if properly set up and maintained, provides an effective tool to track activity over the life of the asset. Computerization of the maintenance system also enables linking of the company’s document management system, warehouse inventory system, and procurement and logistics systems, to name just a few. This linking capability empowers the computerized maintenance management system (CMMS) to reach its full potential.
A HAZOP is a team-based process hazard analysis (PHA) method. Its purpose is to identify hazards and operability issues in a process design. HAZOPs are not fun! Maybe that's not a problem, but they also don't achieve what they could and that is a problem.
Why Don't We Learn What We Should From HAZOPs?
HAZOPs are not as effective as they should be for several reasons, including:
- Tunnel Vision - The focus on small nodes obscures the big picture.
- Guideword Excess - Flow, pressure, temperature, and level are not independent.
- HAZOPs are supposed to identify operability issues, but they really don't explicitly address operability.
- Risk assessment in HAZOPs is typically difficult, ambiguous and not repeatable.
- HAZOP reports are difficult to read and are of limited use.
- Most people don't enjoy HAZOPs and that impacts participation.
The GATE Stream-based HAZOP process avoids these pitfalls via some novel modifications to the process.
Scale management, and the modeling and risk assessments that support it at the design stage of a project, is a critical part of the field development process for deepwater oil and gas developments. In many cases, scaling risk assessments are undertaken very early in the appraisal and concept selection process and with minimal supporting data; however, the implications of such studies can drive field design and affect the commercial viability of a project.
The commissioning activities for massive, technically complex offshore facilities often requires years of 24/7-project involvement by hundreds of workers. There is an abundance of time and ample opportunity for accidents to happen with the rapid increase in risk exposure.
Although preventing accidents is the responsibility of every individual worker, HSSE (health, safety, security and environmental) systems employing the right methodology, robust management tools and relevant experience are critical to safety during every work process. Although computers and software cannot produce oil or gas directly, they can help a project team make informed, timely decisions.
Is it safe enough? This can be a difficult question. Level of Protection Analysis (LOPA) is a structured method that yields a defendable answer to that question.
LOPA uses conservative, order of magnitude values for initiating event frequency, consequence severity and likelihood of failure of protective layers to approximate a risk level for any given scenario. In rigor, it falls between a typical risk matrix approach (as commonly used in HAZOPs) and a quantitative method (QRA). A LOPA is frequently performed after a HAZOP to further investigate significant findings.
Subsea Integrity Management is defined as the management of a subsea system or asset to ensure that it delivers the design requirements while not adversely affecting life or the health of the environment throughout the required life of the field¹.
In this GATEKEEPER series, we introduced the Ultimate Gain Plot (Figure 1) and the variables dead time (DT), time constant (TC), and controller gain (Kp). These four aspects along with a basic understanding of the control loop to be tuned, are all that is required to develop preliminary tuning parameters. The examples in this GATEKEEPER demonstrate simple tuning rules.
This is part two of the GATEKEEPER series on control systems tuning. To effectively tune a control loop, there needs to be an understanding about the dynamics of the system. The intention of this GATEKEEPER is not to provide a detailed review, but to provide an 80/20 solution.