TY - THES

T1 - Evaluation and Optimisation of Matrix Acidizing in OMV Fields

AU - Rodriguez Chavez, Mario-Luis

N1 - embargoed until null

PY - 2007

Y1 - 2007

N2 - The aim of this thesis was to structurally approach matrix acid stimulation optimisation. In order to get a solid grounding in the various disciplines of matrix acidizing the first chapters are dedicated to the theoretical background. This includes near-wellbore damage with its contributing mechanisms, the selection of a candidate well, the type of stimulation treatment, the main mechanisms and chemical reactions occurring during the etching process, the potential risks of creating further damage in sandstone formations, the purpose of the sequence of the injected batches and the various types of additives. The different types of acids and additives currently used in OMV are listed. The issue in optimising matrix acid stimulations is to make the treatments comparable. The prerequisites which must be valid have been defined and stimulated wells with the same set of conditions have been analysed. In order to evaluate the gross effectiveness of the treatments, the Productivity Index has been defined as a success criterion. The evaluation of the treatment progression has been done introducing the instantaneous Injectivity Index of a stage hitting the formation face. The pressure correlation, computed on the basis of a memory gauge recording downhole and a real-time measurement at the surface, mostly matched. Relative Injectivity and the Productivity Index change correlated qualitatively in the majority of the cases.

AB - The aim of this thesis was to structurally approach matrix acid stimulation optimisation. In order to get a solid grounding in the various disciplines of matrix acidizing the first chapters are dedicated to the theoretical background. This includes near-wellbore damage with its contributing mechanisms, the selection of a candidate well, the type of stimulation treatment, the main mechanisms and chemical reactions occurring during the etching process, the potential risks of creating further damage in sandstone formations, the purpose of the sequence of the injected batches and the various types of additives. The different types of acids and additives currently used in OMV are listed. The issue in optimising matrix acid stimulations is to make the treatments comparable. The prerequisites which must be valid have been defined and stimulated wells with the same set of conditions have been analysed. In order to evaluate the gross effectiveness of the treatments, the Productivity Index has been defined as a success criterion. The evaluation of the treatment progression has been done introducing the instantaneous Injectivity Index of a stage hitting the formation face. The pressure correlation, computed on the basis of a memory gauge recording downhole and a real-time measurement at the surface, mostly matched. Relative Injectivity and the Productivity Index change correlated qualitatively in the majority of the cases.

KW - Optimieren Matrixsäuerung Matrixsäuerungen stimulieren Stimulation Stufe Injektion Injektivität Injektivitätindex Produktivität Produktivitätsindex Real-Time Memory-Gauge Erfolgskriterium Korrelation Druckkorrelation

KW - matrix acid stimulation optimisation acidizing candidate well treatment damage Productivity Injectivity Productivity Index Injectivity Index evaluation memory gauge real-time correlation

M3 - Master's Thesis

ER -