Measurement of rock resistivity using inductive method in a cased well

doctoral thesis

• Title (croatian): Mjerenje otpornosti stijena induktivnom metodom u zacijevljenoj bušotini
• Author: Darko Vasić
• Mentor: Vedran Bilas (mentor)
• Mentor: Franjo Šumanovac (komentor)
• Committee member: Ratko Magjarević (predsjednik povjerenstva)
• Committee member: Željko Štih (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; Zagreb
• Defense date and country: 2010-06-02, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering
• Universal decimal classification (UDC): 621.3 - Electrical engineering

Abstract

Rock conductivity measurement is a pivotal method in the open-hole well logging for evaluation of hydrocarbon reservoirs. The conductivity measurement is also required in cased wells as an addition to the radiation methods. Only a contact conductivity tool is available for the cased well application. This thesis proposes an inductive method for simultaneous measurement of the rock conductivity and the casing properties (thickness, conductivity, and permeability) from within single steel-cased well. The analytical electromagnetic model was derived for a transmitter coil inside a steel casing surrounded by a cylindrically and horizontally layered low-conductive medium. Using the space-frequency analysis of the sensitivity on the casing and formation properties, the measurement configuration consisting of one transmitter and three receiver coils was proposed. The investigation radius, vertical resolution, and separability of the casing and formation contributions were discussed. The inverse problem of determination of the casing and formation properties was based on the Bayesian approach. The method was corroborated on the scaled laboratory model of the cased well. The requirements were established for the electronic instrumentation that would embody the proposed method. The single-well trough-casing inductive tool is found to be feasible for operation in the high-temperature environment using commercially available electronic components. The method is applicable for the rock conductivity larger than 1 S/m with the investigation radius of 10 m.

Abstract (croatian)

Mjerenje vodljivosti stijena je ključna metoda u geofizičkom ispitivanju ležišta ugljikovodika iz nezacijevljenih bušotina. Mjerenje vodljivosti je potrebno i u zacijevljenim bušotinama kao dodatak radioaktivnim metodama. Za primjenu u zacijevljenim bušotinama raspoloživo je samo kontaktno mjerenje vodljivosti. U ovome radu je predložena induktivna metoda za istodobno mjerenje vodljivosti stijena i značajki zaštitne cijevi (debljina stijenke, vodljivost i permeabilnost) u zacijevljenoj bušotini. Izveden je analitički elektromagnetski model odašiljačke zavojnice unutar čelične zaštitne cijevi okružene cilindrično i horizontalno slojevitim slabo vodljivim medijem. Na temelju prostorno-frekvencijske analize osjetljivosti na značajke zaštitne cijevi i okolnih stijena, predložen je mjerni sustav od jedne odašiljačke i tri prijamne zavojnice. Istraženi su polumjer ispitivanja, vertikalna razlučivost te odvojivost doprinosa zaštitne cijevi i stijena. Inverzni je problem određivanja značajki cijevi i stijena temeljen na Bayesovom pristupu. Metoda je potvrđena na skaliranom laboratorijskom modelu zacijevljene bušotine. Utvrđeni su zahtjevi na izvedbu elektroničke instrumentacije kojom bi se realizirala mjerna metoda. Potvrđeno je da komercijalno dobavljive elektroničke komponente dopuštaju izvedivost induktivnog uređaja za mjerenje u zacijevljenoj bušotini u okolišu s visokom temperaturom. Mjerna metoda je primjenjiva za vodljivosti stijena veće od 1 S/m s polumjerom ispitivanja od 10 m.

• Keywords: cased well; rock resistivity; casing inspection; inductive measurement; analytical electromagnetic modelling; inverse problems; Monte Carlo Markov chains; scaled modelling; electronic instrumentation; high temperature environment.
• Keywords (croatian): zacijevljena bušotina; otpornost stijena; ispitivanje zaštitne cijevi; induktivno mjerenje; analitičko elektromagnetsko modeliranje; inverzni problemi; Monte Carlo Markovljevi lanci; skalirano modeliranje; elektronička instrumentacija; visokotemperaturno okruženje
• Language: english
• URN:NBN: urn:nbn:hr:168:516635
• Promotion: 2010
• Study programme: Title: Doctoral study programme "Electrical Engineering and Computing"; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, po-dručje tehničkih znanosti (doktor/doktorica znanosti, po-dručje tehničkih znanosti)
• Type of resource: Text
• Extent: ix, 162 str. : graf. prikazi
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-03-20 10:04:02