Drilling is not the only challenge to deepwater drilling economics. Current deepwater technology trends almost exclusively require huge discoveries and unprecedented production rates to ensure acceptable rates of return. Advancements in subsea completion technologies have the potential to reduce costs and improve economics. The system reconfiguration will be accomplished by a workboat instead of a drillship. As a result, the cost of the reconfiguration, or "intervention," could be reduced as much as $200,000 per day compared with systems accomplishing similar functions.
Electrical submersible pumps focuses on the standard ESP configuration. It has the pump, seal chamber section, and motor attached to the production tubing, in this order from top down. In some wellbore completions and unique ESP applications, the arrangement and configuration of the system is modified. For a bottom-intake design, the production fluid is drawn in the intake ports located at the very bottom of the ESP system and discharged out of ports located just below the connection to the seal-chamber section. Because the discharged production fluid cannot flow through the seal-chamber section and motor, it has to exit into the casing or liner annulus and flow past these units.
Multistage hydraulically fractured horizontal well completions have come a long way in the last two decades. Much of this advancement can be attributed to the shale gas revolution, from which numerous transformational tools, techniques, and concepts have led to the efficient development of ultralow-permeability resources on a massive scale. Part of this achievement has been through a widespread trial and error approach, with the higher risk/failure tolerance that is a trademark of the statistical nature of the North American unconventional resource business. However, careful consideration must be taken not to blindly apply these techniques in more permeable tight gas formations, which often cover an extensive range of permeability. Inappropriate application can compromise the effectiveness of the hydraulic fracture treatment and impair long-term well productivity.
Khazzan is a tight to low-end conventional gas field in the Sultanate of Oman, with low porosity and permeability in comparison to conventional formations. The target formations comprise extremely hard, highly stressed rocks at high temperature. The development strategy included vertical wells with massive hydraulic fracture treatments and multistage fractured horizontal wells. The former has been largely successful in the higher-permeability areas, and the economic transition from vertical to horizontal well development, based on rock quality, is continuously evolving. Compared to the rapid learning curve achieved through the more than 80 vertical wells drilled to date, fewer horizontal wells have been drilled, and, as a result, the understanding is still relatively immature.
The paper outlines the technical and operational journey experienced in horizontal wells, to prepare the wellbore and ensure a suitable frac/well connection for successful fracturing and well testing. The paper will describe how the intervention tools and practices have varied between the Barik and Amin formations; depending upon rock quality, frac treatment type, drive to maximize operational efficiency and availability of local resources. The differential application of these techniques, that result in measurable under-flush versus in contrast to the typical North American unconventional practice of defined but limited overflush (e.g., pump-down plug-and-perf will be described). Justification for these different approaches in two very different formations will be demonstrated, including supporting evidence of their relative value.
The obstacles that have been faced, overcome and are still ongoing with this campaign highlight the importance of several critical factors: including multi-disciplinary integration and planning, wellbore construction impacts, contractor performance and tool reliability. Although practices for shale and very low permeability sands are well documented, this paper provides a suite of case histories and operational results for horizontal well intervention techniques used in high-pressure and high-temperature sandstones that are in the very specialized transition zone between conventional and unconventional.
Remotely operated vehicles (ROVs) have facilitated the development of oil and gas resources in deeper water. By enabling access to areas that divers could not safely reach, they have extended capabilities for handling more complex situations and operations in deeper water. In the 1980s, divers used saturated and pressurized systems to do almost all well and subsea equipment intervention, inspection, and repair. If the divers could not complete the repair task and/or inspection, the blowout preventer (BOP) stack or other items had to be pulled out of the water for repair. Subsea television systems were, and still are, used to inspect and monitor hulls and subsea equipment by use of running down guidelines, but they can only view (not do) repairs or other physical tasks.
This session focuses on the latest developments in drilling applications used during exploration and development of wells. These applications are design specifically to improve well costs and schedules. The overall spectrum of well planning, engineering and design, execution will be covered; along with highlights on technical solutions of key challenges in our current drilling environment. The industry, utilises tool and equipment inspection (QA & QC) as an approach to achieve drilling assurance and reliability. Casing While Drilling (CWD) Customised Drilling Fluid for low pressure environment Manage Pressure Drilling (MPD) to solve challenges and optimising the drilling process in narrow pressure conditions Latest LWD equipment for sampling of fluids and pressure measurement and its reliability improvements Optimising “off-line activities”, batch drilling and simultaneous operation practices, etc.
At the 2017 SPE Oilfield Chemistry Conference, an assistant professor from Heriot-Watt University discusses the optimization of squeeze treatments delivered by diving support vessels. This paper describes a novel method of chemical dosage based on time-resolved fluorescence (TRF) that allows a simple, accurate, and efficient quantification of chemicals below parts-per-million ranges, even for double (scale/scale, scale/corrosion) quantification. Rigless coiled-tubing-unit (CTU) interventions can be effective in returning to production wells that have lost electrical-submersible-pump (ESP) efficiency because of organic, inorganic, or mixed scale deposits. The gas-producing carbonate zones of the Ghawar field in eastern Saudi Arabia have been affected by extensive iron sulfide (FeS) scale deposition, reducing overall gas production and increasing risks during well interventions. Two alkali/surfactant/polymer (ASP) floods became operational in the Taber area of Alberta, Canada, in 2006 and 2008.
Deepwater operators continually face technical and environmental challenges to drilling and completing wells safely and efficiently. Radio-frequency identification (RFID) offers the user flexibility in controlling downhole operations without intervention. RFID uses close-proximity sensing to communicate by simply passing a coded tag through an antenna-equipped downhole tool to actuate it.
There are few deepwater-pipeline operators with expertise in pipeline repairs. This paper describes a strategy developed and implemented on deepwater-pipeline intervention, based on a deepwater operational experience built over a decade. The market for subsea vessel operations in field development; inspection, repair, and maintenance (IRM); and subsea well intervention is expected to grow 63% during 2012 to 2016.