Ultra-deep Water Oil Research Articles

Physical-chemical characterization and leaching studies involving drill cuttings generated in oil and gas pre-salt drilling activities.

This work describes characterization and leaching studies of pre-salt drill cuttings from offshore oil and gas exploration in ultradeep waters. The metals Fe, Al, and Ba were present in the highest concentrations in drill cuttings (30000 mg kg-1, 32600 mg kg-1, and 33000 mg kg-1 respectively). The most significant contents of Ba, Al, Fe, Cu, Pb, Mn, Si, and Zn were found in cuttings containing non-aqueous fluids (NADF), but the highest concentrations of Ni and Cr were found in samples containing aqueous fluids (WBDF). The content of total petroleum hydrocarbons (TPHs) in the samples with WBDF fluids ranged from < 5.58 to 15.76 mg Kg-1 while the TPH content of the samples with NADF ranged from 28.46 to 47.16 mg Kg-1. Data on the content of unresolved complex mixtures (UCMs) and sheen tests indicated probable contamination of some cutting samples with oil. Most samples showed some degree of contamination by polycyclic aromatic hydrocarbons (PAHs). The metals present in the highest concentrations in saline and aqueous leachates were Si and Ba. The metals Cd, Cu, Ni, and Zn were present in varied concentrations in the saline leachates, and the metals Si, Ba, Cu, and Zn were found in the aqueous leachates.

Anti-slug control design: Combining first principle modeling with a data-driven approach to obtain an easy-to-fit model-based control

The limit cycle is an unexceptional problem in the oil industry that may cause significant losses in production. Also called slug flow or slugging, the unsteady flow can be handled by feedback control, although nonlinear issues must be considered. As an oil well production valve is opened, its transfer function gain tends to decrease until it reaches zero, meaning that the valve actions lose effect against the system backpressure. Notwithstanding, this sensitivity loss can be compensated by adapting a suitable tuning according to the well operating point. In this work, a methodology to generate this control policy is proposed based on combining first principle modeling with a data-driven approach. The method aims at improving closed-loop performance through a gain scheduling curve resulting from an easy-to-fit model to plant data. A systematic procedure is defined and validated through an actual deployment in a Petrobras ultra-deepwater oil rig. As a result, it was possible to suppress unsteady flow and increase oil production by more than 9%. Although the method has been validated in a satellite offshore well, one expects that feedback control can be used in different scenarios successfully, regardless of the slugging mechanism.

Developing marine and coastal resources in Nigeria: Prospects and challenges

Nigeria, with a coastline of about 853 km bordering the Atlantic Ocean in the area of the Gulf of Guinea, has a maritime area of about 46,000 km2, with significant and diverse natural marine resources. The country has numerous economic activities, in which the highest percentage depends on or is derived from the ocean resources, but it is explicitly clear that her blue economy potentials are far from being fully harnessed. The Nigerian maritime domain is rich with a variety of resources that support livelihoods and economic development. These include established activities like fisheries, shipping, offshore oil and gas, maritime and coastal tourism, marine manufacturing and construction, dredging, etc., and emerging activities such as marine aquaculture, deep and ultra-deepwater oil and gas, offshore wind energy, ocean renewable energy, marine and seabed mining, etc. The main purpose of this paper was to qualitatively investigate the prospects and challenges in developing marine resources in Nigeria and to suggest necessary recommendations. Existing literatures and documents from secondary sources were reviewed. The paper revealed that the challenges in harnessing marine resources in Nigeria are an inadequate scientific data bank, inconsistent government policy, climate change, and inadequate manpower. This paper recommends that the government need to enhance targeted capacity building, particularly at the policy, institutional, legal, and technical levels, for developing coastal states. This may result in effective exploration and mining, which may lead to sustainable marine resources.

Overcoming challenges in field development plan optimization with integrated Production Modelling (IPM): an example of a Giant ultra-deepwater oil field

Overcoming challenges in field development plan optimization with integrated Production Modelling (IPM): an example of a Giant ultra-deepwater oil field

Rare earth elements in drill cutting samples from off-shore oil and gas exploration activities in ultradeep waters

Rare earth elements (REEs) are essential in high technology industries and have great economic value. The monitoring of REEs concentrations in rocks from oil well drill cuttings is critical to avoid environmental contamination and evaluate new sources of these elements. However, information is scarce about the REEs concentrations in drill cuttings. In this work, the concentration of REEs in drill cuttings from oil and gas exploration wells in ultradeep coastal water of Brazilian were investigated at different depths. The drill cutting samples were submitted to microwave-assisted acid digestion prior to the determination of concentration by ICP-MS, using Rh as internal standard for calibration. The limits of quantification (LoQ) ranged from 3.3 μg kg−1 for Ho to 198 μg kg−1 for Sm. The accuracy was evaluated by analyzing certified reference materials for rocks. The obtained REEs concentrations agreed with the certified values, reaching 83%–105% agreement. The drill cutting depth profile analysis indicates Ce, La, Nd, Sm, and Eu concentrations up to mg kg−1. The REEs concentrations obtained in drill cutting depth profile was analyzed by principal component analysis (PCA), and hierarchical cluster analysis (HCA) identified tendency and similarity between drill cutting samples. Three groups were formed according to the composition of the REEs. In addition, the concentration of these chemicals elements varied at different depths. The analysis of drill cuttings revealed REEs concentrations up to the mg per kg-range (ppm), potentially making this disposable material an alternative source for REEs extraction, and adding value to this material.

The Evolving Role of Oil and Gas Companies in the Energy Industry

This paper provides a review of the evolving role and characteristics of the global oil and gas companies, which increasingly come in a variety of flavors. It also surveys the different types of global oil and gas companies that include national oil companies (NOCs), international oil companies (IOCs), Independents, and oilfield services companies (OFSCs). The continued rise of NOCs, accelerated by high oil prices, has seen the balance of control over most of the world’s hydrocarbon resources shift decisively in their favor. Their ability to access capital, human resources and technical services directly from oil field service companies, and to build in-house competencies, allows them to operate independently of Investor Owned Companies in most instances. The demand on NOCs continues to evolve with the global energy landscape to reflect variations in demand, discovery of new ultra-deep water oil deposits, and national and geopolitical developments. NOCs, traditionally viewed as the custodians of their country's natural resources, have generally owned and managed the complete national oil and gas supply chain from upstream to downstream activities. Having secured their home base, NOCs have emerged as joint venture partners with the IOCs and increasingly as their competitors, seeking international upstream and downstream acquisition and asset targets. The key question is whether this emerging landscape will undermine the sustainability of the IOC resource-ownership business model. Are the challenges of declining production in existing oil fields replacing oil and gas reserves in restricted access or higher cost areas, and the declining of the operating profit margins yet sufficient to reach a tipping point?

Postulated failure analyses of a spread-moored semi-submersible

Semi-submersibles, best-suitable for oil and gas exploration in ultra-deep waters, possess attractive stability characteristics. While well-defined installation practices also bound them, failure of mooring lines shall pose challenges to their functional safety. Postulated failure analyses of a semi-submersible in 1500 m water depth in the Gulf of Mexico, installed with two other moorings namely: spread catenary and taut-moored, are discussed, and the fatigue damage is estimated using S–N curve approach. Results showed that while the motion responses of the semi-submersible with the proposed spread mooring are within the permissible limits, the fatigue life of the remaining mooring under the postulated failure condition is significantly decreased. Results show that the motion responses of semi-submersible with the proposed spread mooring are found to be within the permissible limits, except for a marginal increase under the mooring failure case. Tension in the remaining mooring lines is found to be dependent on the position of the failed mooring lines.

Decommissioning of deep and ultra-deep water oil and gas pipelines: issues and challenges

When production facilities reach the end of their economic life in the offshore oil and gas industry, field owners must decide whether to replace, extend the life of, or decommission assets. The decommissioning of deep and ultra-deep water oil and gas pipelines has become a serious issue in recent years because it is a complex process and presents challenges to stakeholders. In this paper, we review the current practices of pipeline decommissioning in different regions of the world and then highlight issues and challenges related to such activities in deep and ultra-deep waters. These issues and challenges can be broadly categorised into technical (e.g., selection of appropriate decommissioning procedures for handling hazardous pipelines), financial or economic, health and safety legislation, environmental, and human or organisational issues (such as lack of requisite skills, knowledge and expertise). In order to address the challenges identified in the study, some directions for future research are suggested. [Received: December 7, 2016; Accepted: October 17, 2017]

Decommissioning of deep and ultra-deep water oil and gas pipelines: issues and challenges

Decommissioning of deep and ultra-deep water oil and gas pipelines: issues and challenges

Parametric Dimensional Analysis on the Structural Response of An Innovative Subsurface Tension Leg Platform in Ultra-Deep Water

The innovative Subsurface Tension Leg Platform (STLP), which is designed to be located below Mean Water Level (M.W.L) to minimize direct wave loading and mitigate the effect of strong surface currents, is considered as a competitive alternative system to support shallow-water rated well completion equipment and rigid risers for large ultra-deep water oil field development. A detailed description of the design philosophy of STLP has been published in the series of papers and patents. Nonetheless, design uncertainties arise as limited understanding of various parameters effects on the structural response of STLP, pertaining to the environmental loading, structural properties and hydrodynamic characteristics. This paper focuses on providing quantitative methodology on how each parameter affects the structural response of STLP, which will facilitate establishing the unique design criteria as regards to STLP. Firstly, the entire list of dimensionless groups of input and output parameters is proposed based on Vaschy- Buckingham theory. Then, numerical models are built and a series of numerical tests are carried out for validating the obtained dimensionless groups. On this basis, the calculation results of a great quantity of parametric studies on the structural response of STLP are presented and discussed in detail. Further, empirical formulae for predicting STLP response are derived through nonlinear regression analysis. Finally, conclusions and discussions are made. It has been demonstrated that the study provides a methodology for better control of key parameters and lays the foundation for optimal design of STLP. The obtained conclusions also have wide ranging applicability in reference to the engineering design and design analysis aspects of deepwater buoy supporting installations, such as Grouped SLOR or TLR system.

Wind Induced Response of Spar-mooring-riser System

In recent decades, the exploitation of hydrocarbon reservoirs under the seas and oceans has been regarded as a viable alternative. Several types of floating structures are utilized in deep and ultra-deep water oil and gas exploration and production. Spar platforms are the most recent type of platforms to be designed and utilized in deep water environments. This type of platform is an assemblage of a cylindrical hull, moorings and risers that responds to hydrodynamic and aerodynamic loads in a complex manner. Coupled behaviours of spar–mooring–riser system influenced by the wind load in random wave environment have been studied using coupled analysis method. The spar–mooring–riser system has been analysed to predict system responses induced by wind action under a long crested random wave using finite element approach. Wind load induces a significant shift in the spar position away from its original place in the random sea state in addition to a notable heave motion reduction. The top tension magnitude of the moorings and riser significantly increased. The diminishing fluctuation highlights the firmness and controlled oscillations of the spar platform relative to its new mean position.

Ringing response of offshore triceratops

Triceratops is a new generation offshore platform, proposed for oil and gas exploration in ultra-deep waters. Deck is supported by buoyant legs, but isolated from each other by ball joints. Buoyant legs are taut-moored to the seabed using tethers with high initial pretension. The presence of ball joints makes the platform less sensitive to the encountered environmental loads. The present study investigates transient response of triceratops under distinctly high sea waves through numerical studies. Spectral analysis is carried out to estimate the ringing response, which is highly nonlinear. While ringing waves are simulated with parametric variation, JONSWAP spectrum is used to simulate the time series of large irregular waves causing ringing response on triceratops. Based on the numerical studies carried out, a gradual decay is seen in the response of buoyant legs looking similar to that of a beat phenomenon. Deck response shows a significant reduction in rotational degrees-of-freedom than that of the buoyant legs due to the presence of ball joints, which aids the platform to remain operational even under high sea states. Statistical analyses on tether tension variation show that ringing caused by strong asymmetric waves is responsible for causing impact load on the platform.

A finite element method assessment of a Steel Tube Umbilical (STU) cable subjected to crushing load: Comparison between two and three-dimensional approaches

Umbilical cables are fundamental equipment used in deep and ultra-deep water oil and gas production systems. The complexity of such structures usually enforces the use of numerical tools. This paper presents and compares two different numerical approaches for prediction of stress and strain fields in the umbilical cable components under crushing loads, which are imposed to the umbilical during laying operation. The first approach, presented in a previous work [1], is based on a joint analysis using a two-dimensional finite element model fed by analytical models, which represent three-dimensional effects. The second approach, used here as a paradigm, is based on a full three-dimensional finite element model, in which the three-dimensional effects are intrinsically considered. An armoured Steel Tube Umbilical Cable is used as a case study in order to compare both methodologies. It is shown that, while being much faster, the two-dimensional approach yields consistent results when focus is directed onto the components of the central core, as steel tubes. Elastic-plastic behavior is adopted for the steel tubes in both models.

Comparative analysis of separation technologies for processing carbon dioxide rich natural gas in ultra-deepwater oil fields

Offshore oil production in ultra-deepwater, with associated natural gas showing high carbon dioxide content and high gas to oil ratio, poses stringent constraints to upstream gas processing technologies. Under such circumstances, oil and gas are processed in Floating Production Storage and Offloading rigs, whose topside facilities are limited in terms of weight and footprint of equipment. Energy demands, supplied by on-site generation, also reduce the availability of space and weight to oil and gas processing. This work evaluates carbon dioxide separation alternatives applicable to this challenging scenario in terms of technical, economic and environmental aspects, considering early enhanced oil recovery as the destination of carbon dioxide. The Brazilian Pre-Salt fields are used as case study due to their unusual high capacity gas processing on the production topside, a consequence of the high gas to oil ratio and carbon dioxide content. The set of studied carbon dioxide separation technologies encompasses membrane permeation, chemical absorption by aqueous methyl diethanolamine with piperazine, physical absorption with propylene carbonate and hybrid variants physical absorption and membranes, membranes and chemical absorption, and two stages membrane, technically assessed by process simulation. Due to the continuous injection of carbon dioxide to enhanced oil recovery, the reservoir content of carbon dioxide increases along production life-cycle, which means that the performances of technologies have to be compared under short-term, mid-term and long-term carbon dioxide content in the associated gas, respectively, of 10%, 30% and 50% (mol), for gas production of 6 million sm3/d. Chemical absorption exhibits the lowest hydrocarbon losses and the lowest specific electric power consumption at the expense of the highest footprint, for all investigated scenarios. The lowest life-cycle costs are for chemical absorption and two stages membrane, respectively $0.57 and $0.46 million/GJ of exported gas, while the largest cost belongs to the hybrid membrane and chemical absorption ($1.78 million/GJ of exported gas). Chemical absorption holds the lowest carbon dioxide emission per ton of injected carbon dioxide (0.15 t/t), seconded by membrane permeation (0.19 t/t). Hybrid membrane and chemical absorption inherits the small footprint of membrane permeation and, despite its highest life-cycle cost, is recommended for flexibility reasons due to increasing carbon dioxide content in the reservoir life-time in cases of ultra-deepwater fields with high gas to oil ratio, high carbon dioxide content and early carbon dioxide enhanced oil recovery. Contrarily to the widely acceptance of membrane permeation as a leading small footprint solution, the overall performance analysis, under the adopted premises, remarkably favors chemical absorption.

Shape memory alloy actuated accumulator for ultra-deepwater oil and gas exploration

As offshore oil and gas exploration moves further offshore and into deeper waters to reach hydrocarbon reserves, it is becoming essential for the industry to develop more reliable and efficient hydraulic accumulators to supply pressured hydraulic fluid for various control and actuation operations, such as closing rams of blowout preventers and controlling subsea valves on the seafloor. By utilizing the shape memory effect property of nitinol, which is a type of shape memory alloy (SMA), an innovative SMA actuated hydraulic accumulator prototype has been developed and successfully tested at Smart Materials and Structure Laboratory at the University of Houston. Absence of gas in the developed SMA accumulator prototype makes it immune to hydrostatic head loss caused by water depth and thus reduces the number of accumulators required in deep water operations. Experiments with a feedback control have demonstrated that the proposed SMA actuated accumulator can provide precisely regulated pressurized fluids. Furthermore the potential use of ultracapacitors along with an embedded system to control the electric power supplied to SMA allows this accumulator to be an autonomous device for deployment. The developed SMA accumulator will make deepwater oil extraction systems more compact and cost effective.

New Improvements to Deepwater Subsea Measurement

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 25686, “More Improvements to Deepwater Subsea Measurement: Overview,” by W. Letton, Letton Hall Group; J.M. Pappas, Research Partnership To Secure Energy for America; and J. Shen, Chevron, prepared for the 2015 Offshore Technology Conference, Houston, 4–7 May. The paper has not been peer reviewed. In an effort to develop new measurement technologies for ultradeepwater oil and gas production, the US Department of Energy’s National Energy Technology Laboratory under the Research Partnership To Secure Energy for America (RPSEA) has initiated a new project. This project, titled More Improvements to Deepwater Subsea Measurement, has addressed those gaps that were identified by an earlier RPSEA project as the most pressing for multiphase-flow measurement. Introduction Approximately 15 years ago, as offshore production in the Gulf of Mexico and elsewhere moved off the continental shelf and into truly deep water, it became apparent that methods of measuring the flow of oil and gas would have to change in a significant manner. Not only did formidable technical challenges exist in performing production tests on wells that were many miles away in 1000 m or more of water, but the economics of installing test lines to perform such tests simply was not acceptable. Production from many wells would be commingled, and one of two alternatives would have to be chosen: Either a clever way of testing well rates from the combined flow would be developed, or each well’s rate of production would be measured before commingling. Discussion History. Past efforts of RPSEA and others to research improving deepwater exploration-and-production operations are detailed in the complete paper. At the conclusion of one such RPSEA project, running from 2008 to 2011, several leaders in a joint-industry project ( JIP) that had supported that effort expressed an interest in a followup RPSEA project to refine certain results from the first project, and to investigate those areas where it was felt there were still questions needing answers. Consequently, a new proposal was submitted for RPSEA’s consideration, resulting in the new RPSEA project: 10121-4304-01, More Improvements to Deepwater Subsea Measurement. The following topics were identified: Deepwater fluid sampling Deepwater meter-verification technology Early kick detection Downhole differential-pressure-sensor development Virtual-flowmeter evaluation Detection of meter fouling Each of these topics could have qualified as a project on its own, but the fact that the common thread of measurement ran through all, requiring the same kind of expertise in investigators, suggested that grouping the various parts under a single RPSEA project, managed by those experienced in measurement, made good sense. Therefore, this was the approach taken once again.

Project Atlantis

This paper explores the reach and use of subsea engineering. Subsea engineering presents many new challenges and opportunities for engineers from any discipline. The fundamental engineering challenges facing today’s ultra-deepwater oil and gas production reside under a new engineering discipline, the subsea engineer. Designing subsea systems for 30-year-long controllability, safety, maintenance, and real-time optimization are critical issues and present an open-ended problem. Safety is absolutely a primary focus on any subsea production system design. There must be multiple independent safety paths in place to isolate a producing well. The most common subsea safety system is located within the well. Pioneering work performed at the university of Houston provided mathematical relationships to predict the flow regime given gas and liquid velocities, including dispersed bubble flow, elongated bubble flow, slug flow, stratified flow, etc. There is an unexplored coupling between the transient multiphase flow and the heat transfer. The field of modeling multiphase transient transport is important to the subsea architecture design and real-time optimization of subsea production.

Deep-water riser fatigue monitoring systems based on acoustic telemetry

Marine risers play a key role in the deep and ultra-deep water oil and gas production. The vortex-induced vibration (VIV) of marine risers constitutes an important problem in deep water oil exploration and production. VIV will result in high rates of structural failure of marine riser due to fatigue damage accumulation and diminishes the riser fatigue life. In-service monitoring or full scale testing is essential to improve our understanding of VIV response and enhance our ability to predict fatigue damage. One marine riser fatigue acoustic telemetry scheme is proposed and an engineering prototype machine has been developed to monitor deep and ultra-deep water risers’ fatigue and failure that can diminish the riser fatigue life and lead to economic losses and eco-catastrophe. Many breakthroughs and innovation have been achieved in the process of developing an engineering prototype machine. Sea trials were done on the 6th generation deep-water drilling platform HYSY-981 in the South China Sea. The inclination monitoring results show that the marine riser fatigue acoustic telemetry scheme is feasible and reliable and the engineering prototype machine meets the design criterion and can match the requirements of deep and ultra-deep water riser fatigue monitoring. The rich experience and field data gained in the sea trial which provide much technical support for optimization in the engineering prototype machine in the future.

Worst‐case design of subsea production facilities using semi‐infinite programming

The problem of designing novel process systems for deployment in extreme and hostile environments is addressed. Specifically, the process system of interest is a subsea production facility for ultra deepwater oil and gas production. The costs associated with operational failures in deepwater environments are prohibitively high and, therefore, warrant the application of worst‐case design strategies. That is, prior to the construction and deployment of a process, a certificate of robust feasibility is obtained for the proposed design. The concept of worst‐case design is addressed by formulating the design feasibility problem as a semi‐infinite optimization problem with implicit functions embedded. A basic model of a subsea production facility is presented for a case study of rigorous performance and safety verification. Relying on recent advances in global optimization of implicit functions and semi‐infinite programming, the design feasibility problem is solved, demonstrating that this approach is effective in addressing the problem of worst‐case design of novel process systems. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2513–2524, 2014

Research Funded by DOE/RPSEA Advances Ultradeepwater Technology

Technology Update A number of research projects awarded by the Research Partnership to Secure Energy for America (RPSEA), with funding and oversight by the United States Department of Energy’s National Energy Technology Laboratory (NETL), have shown solid potential to advance deepwater and ultradeepwater (UDW) oil and gas development. The DOE/RPSEA projects are among more than 15 to be featured in a session on funding new E&amp;P technologies on 7 May at the Offshore Technology Conference (OTC) in Houston. Chairing the session will be James Pappas, vice president of ultradeepwater at RPSEA. Nine of the technologies developed through this research are discussed herein. One of the projects, highlighted on the cover of the January 2014 issue of JPT, is the Lockheed Martin Marlin autonomous underwater vehicle. This system has the following advantages over remotely operated vehicle (ROV) systems: 3D model generation in hours vs. days; the use of smaller vessels with fewer crew members; no need for umbilical management; realtime change detection, enabling on-site assessment of survey results and structural anomalies; rapid assessment capability of potential environmental damage; and the ability to generate accurate, geo-registered models for structural integrity assessment. Also under consideration is the inclusion of high-resolution visual imaging to enable accurate subsea measurement of flow rate from a blowout or from ocean floor seeps for predrilling site investigations. The project is in its final phase of development and scheduled to be complete by June. Another interesting set of projects deals with metocean issues that affect UDW development. Studies in this area have continued since the early days of UDW research and development within RPSEA. The first efforts studied the US Gulf of Mexico (GOM) loop currents to develop a better hurricane forecasting model, because these relatively warmer currents often increase hurricane intensity. The goal of these projects was to develop a better long-range forecast (of up to 90 days) of hurricane activity in the GOM. The newer models with higher resolution potentially could better describe the density of the spiral rain bands caused by higher wind velocities farther from the center of the storm. The spacing of these bands appears to have a greater influence on the extent of damage sustained by an offshore vessel than hurricane classification or size, as the spacing more directly affects seawater wave height.