Celso Kazuyuki Morooka

Case-based reasoning in offshore well design

Petroleum well drilling is an expensive and risky operation. In this context, well design presents itself as a fundamental key to decrease costs and risks involved. Experience acquired by engineers is notably an important factor in good drilling design elaborations. Therefore, the loss of this knowledge may entail additional problems and costs. In this way, this work represents an initiative to model a petroleum well design case-based architecture. Tests with a prototype showed that the system built with this architecture may help in a well design and enable corporate knowledge preservation.

Development of intelligent systems for well drilling and petroleum production

Domains where knowledge representation is too complex to be described analytically and in a deterministic way is very common in the petroleum industry, particularly in the field of exploration and production. In these domains, applications of artificial intelligence techniques are very suitable, especially in cases where the preservation of corporate and technical knowledge is important. The Laboratory for Research on Artificial Intelligence Applied to Petroleum Engineering (LIAP) at Unicamp, has, during the last 10 years, dedicated research efforts to build intelligent systems in well drilling and petroleum production fields. In the following sections, recent advances in intelligent systems, under development in the research laboratory, are described.

Case-based system: indexing and retrieval with fuzzy hypercube

In some applications with case-based systems, the attributes available for indexing are better described as linguistic variables instead of receiving numerical treatment. In these applications, the concept of fuzzy hypercube can be applied to give a geometrical interpretation of similarities among cases. The paper presents an approach that uses geometrical properties of fuzzy hypercube space to make indexing and retrieval processes of cases.

Whipping Phenomenon Caused by the Internal Flow Momentum on the Catenary Risers of Offshore Petroleum Fields

A laboratory-scale model was designed to investigate the influence of the internal flow of two-phase oil and gas mixtures on the motion of slender risers hanging in catenary configuration used for offshore petroleum production in deep waters. The behavior of the riser arises from the interplay of various dynamic phenomena: the long length and relatively small diameter of the pipeline confers a cable-like elasticity to the system, which, under static loading, assumes a catenary shape; dynamic excitation caused by environmental conditions generates oscillations. The internal flow momentum may impose a natural whipping displacement — compounding swinging and bending — adding to the concerns of stress and fatigue. The internal flow may display different two-phase patterns (bubbles, slugs, intermittent, annular or stratified mixtures) possessing completely different characteristics; also, the flow-induced dynamic loading depends on the flow rates of both oil and gas phases. Although computer codes have been developed to simulate the motion of risers, there is much need for experimental validation. This research attempts to discern the effects of the internal flow, discriminating it from the other dynamic phenomena. Accelerometers and video acquisition were employed to verify the phenomenon and to determine the frequency spectrum of the oscillations.Copyright

Dynamic positioning system of semi-submersible platform using fuzzy control

The purpose of this paper is the study of fuzzy control applied to a Dynamic Positioning System (DPS) of semi-submersible platforms. A numerical simulator program in time domain was coded using mathematical models of the floating platform dynamics and the external forces (wind, current, wave and thruster) that act on the platform. Subsequently, a fuzzy controller applied to DPS was developed. The Fuzzy controller and the Proportional-Integral-Derivative (PID) controller were then subjected to the same environmental conditions in order to compare their performance. Keywords : Offshore petroleum, ocean waves, floating drilling platform, and dynamic positioning system

Control: PCP - An Intelligent System for Progressing Cavity Pumps

This paper describes an intelligent system for the management and control of petroleum wells operating with progressing cavity pumps (PCP), named CONTROL: PCP. The purpose of CONTROL: PCP is to maintain the operational conditions of PCPs within the established limits, reduce the operational costs, maximize the useful life of the equipment, and, consequently, increase the profitability of the petroleum wells. The architecture of the system involves expert knowledge for handling an existing database.

Smart oil recovery

Fuzzy-logic-based expert systems assist Brazilian engineers with the drilling, pumping, and processing of offshore oil, cutting costs without compromising safety. The authors discuss these applications of fuzzy logic control.

Analysis method for contact forces between drillstring-well-riser

This paper proposes a methodology to estimate the contact forces generated by the drillstring against the wellbore and the marine drilling riser system. A new procedure for overall analysis of the drill string behavior inside the riser and wellbore is described. This is important in the safety analysis of the wellhead equipment and also in planning drilling operations. The results also suggest that the forces should be used in the dynamic analysis of marine riser system.

Dynamic Behavior of a Vertical Riser and Service Life Reduction

In the last years, the most of offshore oil and gas reserves discoveries in Brazil are placed in ultra-deep water depths. Petroleum production from these offshore fields needs developments with novel solutions in terms of necessary technologies and economical viability. The use of vertical rigid risers such as top tensioned risers (TTR) and others like combined systems as self standing hybrid risers and steel catenary risers for ultra-deep waters have shown viable from both, technical and economical aspects. However, there are needs for detailed studies on their dynamic behavior in order to improve, particularly, the understanding of influence of the environment as wave and current, and floating platform oscillations at the riser top. The present work presents studies on vertical top tensioned riser dynamic behavior through time domain simulations of its displacements and respective, bending moments and stresses. Influences of the vortex induced vibrations (VIV) and waves on the riser service life reduction are analyzed. Maximum and minimum envelops for displacements and stresses along riser length are shown.Copyright

Dynamic Behavior of a Semi-Submersible Platform Coupled With Drilling Riser During Re-Entry Operation in Ultra-Deep Water

The present study deals with the dynamics of a semi-submersible platform coupled with a free-hanging vertical rigid riser during the re-entry operation in ultra-deep water. The reentry operation occurs after the drilling phases are accomplished which only use the bare drillstring. The re-entry operation entails positioning the subsurface Blow-Out-Preventer (BOP) above the wellhead and installing it to the wellhead. During this operation, the BOP is suspended by the drilling riser. The placement and installation is time consuming and requires a great amount of accuracy. One challenge is the effects of platform motions on the installation procedure. The present work was carried out with the aim to understand the influence of platform motions during the re-entry operation in ultra-deep waters. Another benefit of this study is the knowledge of the effect of platform motions on the drilling riser and BOP which leads to the possibility of drilling more than one well without the need to raise the BOP to the surface. This could greatly reduce the amount of time needed to drill subsurface wells which in turn, reduces overall operational costs. A numerical simulation in time domain has been carried out using a non-linear model for the platform dynamics. The dynamics of a free hanging drilling riser and a dynamic positioning system (DPS) of the semi-submersible platform are included in the numerical model. Simulation results in time domain of the platform displacements with DPS and riser displacement are shown. A discussion of riser displacement and DPS control is also included.Copyright