The evolution in the use of subsea technology has seen advancement from one well in the Gulf of Mexico in 1961 to more than 750 wells in a wide variety of locations by the end of 1993. Along with the growth in numbers, the industry has seen rapid advances in technology, increased distances from the host facility, and water depth records. This paper gives an overview of the evolutionary changes in subsea applications, with emphasis on the most active regions and on some of the milestone installations that shaped the technology advance.
Deepwater production systems are considered for the 300-500 m water depth range in the Bay of Campeche. In comparison with the northern Gulf of Mexico, the physical environment is found to have similar seafloor soils; similar winter storms; no Loop Current; less severe hurricanes; and weak earthquake-induced groundmotions. Oil reservoirs are expected to be larger than those in the northern Gulf, and well flow rates greater. Under these conditions, and based on industry experience in various offshore oil provinces, steel piled jackets, compliant piled towers, tension leg platforms, and floating production systems, alone or in connection with subsea production systems, are all judged to be technically viable candidates for full-field development with permanent structures. Introduction So far, production of the prolific reservoirs in the Bay of Campeche has been limited to water depths less than 200 m (Figure 1). These reservoirs are characterized by heavily faulted limestones having high vertical and horizontal permeabilities (Franco, 1978). Saturated oil column thickness is typically several hundred meters and areal extent of the larger reservoirs ranges from 10 - 90 square km (Santiago and Baro, 1990; Downer, 1978). Well production rates are high. Wells in the Akal and Nohoch fields produced an average of 35,000 bopd in their early years (Rintoul, 1981). Rates of 16,000 bopd have been common throughout the Campeche fields (Baker, 1985). While most of the oil is the heavy Maya crude, with an API gravity of around 20 to 30, some of the fields have the lighter lstmo crude, with an API gravity of around 30 to 40 (Madeley, 1981; Santiago and Baro, 1990). The gas/oil ratio averages about 650 scf/bbl (Santiago and Baro, 1990). The gas contains H2S (Anonymous, 1979). Production platforms are steel piled jackets. Gas, oil, and water are separated on the platforms, and then oil and gas are piped to shore for further processing and disposition. It is anticipated that similar reservoirs will be discovered in the deeper continental slope water to the west of the known reservoirs, as shown in Figure 1. These reservoirs are expected to have heavier crude (23-30 degrees API) with lower gas/oil ratios (around 200 scf/bbl). The purpose of this paper is to discuss production systems that could be used to develop reservoirs in water depths of 300-1000 m, with emphasis on the 300-500 m depth range, which would likely be explored and developed first. In the following sections, the physical environmental conditions affecting platform and pipeline design are discussed first. Then, the pros, cons, and selection drivers of candidate deepwater production systems are discussed, and recent experience is described. Finally, some economic considerations are discussed. P. 161^
The evolution in the use of subsea technology has seen advancement -from I well in the Gulf of Mexico in 1961 to over 750 wells in a tide variety of locations by the end of 1993. Along with the growth in numbers, the industry has seen rapid advances in technology, distances from the host facility, and water depth records. This paper gives an overview of the evolutionary changes in subsea applications, with emphasis on the most active regions, and some of the milestone installations that shaped the technology advance. INTRODUCTION In the 33 years since the first subsea well was completed in the Gulf of Mexico in 1961, the use of subsea wells has spread to most offshore producing areas of the world, as shown by Figure 1. By late 1993, a total of approximately 752 subsea wells have been completed worldwide, with over 440 of these wells still in service. This paper will provide an overview of subsea technology development by focusing on three areas which exemplify the technology used worldwide:The Gulf of Mexico and West Coast of North AmericaThe North Sea andThe Campos Basin of Brazil. SUBSEA TECHNOLOGY OVERVIEW Subsea wells have been used in a variety of configurations. Typical arrangements shown by Figure 2 include single satellite wells consisting of subsea trees situated on their individual guidebases; subsea trees located on steel template structures with production manifolds; and clustered well systems which are single satellite wells connected to a nearby subsea manifold. These various design layouts and hybrid arrangements of them are usually produced back to platforms or to floating production vessels, although some have also been produced to shore. Over 50 floating production systems (FPS) have been deployed worldwide, with over 30 currently active. Maximum water depth experience of subsea wells has reached 2562 feet in the Campos Basin and 2245 feet in the Gulf of Mexico. Figure 3 shows the water depth experience range for worldwide subsea wells. The deepest production experience to date is the Aquila extended well test by Agip in 2788 feet of water in the Mediterranean in 1993. Maximum producing distance to the host facility is 30 miles for a gas reservoir and 12 miles for an oil reservoir, both in the North Sea. Most subsea wells have produced by natural flow, but over 110 wells have been produced by gas lift. Pressure maintenance with subsea water injection wells is used where needed. Well servicing or workovers can be performed using reentry from a floating drilling unit or jackup, Also, specialized techniques such as through flowline (TFL) operations can be performed downhole by pumping tools from the surface host facility through the flowlines and down the tubing. Chemicals can be pumped into the formation through the flowlines, and chemicals can be injected into the subsea tree or downhole by pumping from the surface host facility through hydraulic hoses in the subsea control umbilical. Pressure and temperature can be monitored at the tree or even downhole.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.