Novel Subsea Production System Reduces Costs, Heightens Efficiency in China’s Bohai Bay
Chris Carpenter_
This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 36730, “Novel Subsea Production System for Shallow-Water Oilfield Development in China Bohai Bay,” by Tao Xie, SPE, State Key Laboratory of Offshore Oil and Gas Exploitation, CNOOC, and China University of Petroleum-Beijing, and Lei Zhang and Qilong Zhang, State Key Laboratory of Offshore Oil and Gas Exploitation and CNOOC, et al. The paper has not been peer-reviewed. Copyright 2026 Offshore Technology Conference.
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The operator’s Bohai oilfield is its largest crude oil production base, with an annual production of 265 MMbbl. However, because Bohai Bay is an internal bay with an average water depth of 60 ft, commonly used jacket platforms are prohibited. This paper presents an engineering solution tailored for shallow-water oilfield development in Bohai Bay, addressing the confluence of spatial constraints, marginal economics, and environmental conditions that have rendered such reserves stranded.
Technological Challenges
Dimensional Specifications of Subsea Equipment.
Subsea production equipment is deployed in water depths spanning hundreds to thousands of meters. Conventional subsea trees require heavy-lift-vessel deployment. However, shallow-water environments mandate compact optimization of equipment geometry to mitigate collision risks with surface vessels constrained by operational draft limitations.
Protective Structural Configuration.
In deepwater environments, subsea production equipment typically employs minimalist overhead shielding to mitigate dropped-object hazards, thereby imposing modest structural requirements. Conversely, shallow-water operations mandate robust protective architectures for critical components, including subsea trees and manifolds, to withstand threats from anchor deployments and fishing-trawl interactions. More stringently, navigation-restricted zones enforce absolute prohibition of any seabed-protruding installations.
Operational Environmental Constraints.
In contrast to deepwater conditions, shallow-water marine environments exhibit substantially elevated suspended sediment concentrations, resulting in severely degraded optical visibility, meaning that remotely-operated-vehicle (ROV)-based operations are impracticable. However, diving operations constitute high-risk activities subject to stringent environmental limitations, thereby yielding substantially reduced operational efficiency.
Wellhead Layouts.
A distinguishing characteristic of shallow-water subsea lies in disparate spacing requirements arising from operational methodologies and installation assets. Use of jackup drilling platforms necessitates critical consideration of cantilever beam reach as a primary design parameter, supplementing equipment dimensions and manifold spacing criteria. The governing design principle thus becomes the minimization of platform jacking cycles and repositioning events, thereby optimizing operational efficiency while reducing installation costs.