Integrity Management (IM) planning is a challenge that is currently center-stage with oil and gas operators as the downturn has led to focused attention on extending the life of existing assets while optimizing ongoing operating expenditure. This is particularly true in the deepwater basins of the world, where capital costs are high, the cycle time to deliver new facilities is long, and the life extension of existing assets to support hub and spoke tieback developments is often commercially favorable.
Blockage remediation methods vary widely depending on the nature and location of the blockage, available facilities, targeted outcome(s) and costs involved. In Blockage Remediation Part 1: Blockage Characterization and Detection, we discussed the importance of correctly understanding the nature of a blockage in order to formulate an effective remediation solution.
This GATEKEEPER will focus on commonly applied remediation methodologies used in the industry, as well as discuss the GATE blockage remediation approach.
In spite of robust design, adequate infrastructure and a well planned and executed operating strategy, partial or fully blocked pipelines, with loss of production in many cases, is a reality. This series of two articles discusses the diagnosis, detection and remediation of oil and gas production system blockages in detail. The current issue focusses on blockage characterization and detection.
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 the previous parts of this series, it was established that wax deposition is an issue that arises whenever an oil composition containing appreciable wax content encounters flow, temperature, and pressure that are conducive for solids formation. The effective development of wax management strategies during Front End Engineering Design (FEED) can serve to mitigate or perhaps even prevent the high costs associated with wax remediation.
Wax deposition modeling is essential to estimate the wax deposit thickness over time in support of wax management strategy development for susceptible systems. The objective of this GATEKEEPER is to provide a high-level overview of the model commonly used in the industry to estimate the wax deposition.
Wax deposition is an issue that arises whenever an oil composition containing appreciable wax content encounters flow, temperature, and pressure that are conducive for solids formation. Wax deposition can potentially occur anywhere in the system from the reservoir to the refinery.
The natural decline in the reservoir energy will impact the flowrate of oil, gas or water, thereby creating instabilities and resulting in decreased production. Artificial lift is used in oil-dominated or liquid-loaded gas systems to increase and stabilize hydrocarbon production, as well as to minimize flow assurance and operational risks, such as slugging in the subsea production system. Artificial lift methods transfer energy to the produced fluid with the objectives of reducing the fluid density and the pressure head or boosting the flowing pressure.
In the oil and gas industry, many different approaches have attempted to provide accurate predictions of the hydrodynamics and flow-related characteristics of fluids. However, factors such as modeling the concentration of a dispersed phase, the determination of drag and lift forces and relative motion between phases, and the need to consider particles with ranges of shape, size and density means that the only viable option in many situations is the use of computational fluid dynamics (CFD) to develop accurate solutions for challenging multiphase flow problems.
Topsides separators are designed to handle a relatively constant flow of liquid and gas, but may also have an allowance for slugs. Under certain operating conditions (low flow rate, over-sized flowline ID and unfavorable flowline profile), gas and liquid are not evenly distributed throughout the flowline, but consist of large plugs of liquid followed by large gas pockets. This is called slug flow.
Hydrates and hydrate plugs can restrict flow, damage equipment, and potentially jeopardize the safety of personnel. Hydrates are formed as a result of the bond between gas and water molecules that occur at high-pressure, low-temperature environments. In deepwater, hydrates can form at temperatures higher than the ambient seabed temperature; hence, prevention and remediation of hydrates is a serious concern for deepwater operators.