PhD defence by Maiya Medetbekova - "Production performance of radial water-jet drilled wells: a modelling and laboratory study"

Chalk, due to its low matrix permeability, requires stimulation of the near-wellbore area to create conductive flow paths for the fluid flow. Matrix acidizing and acid fracturing methods are well-known solutions implemented in the North Sea chalk reservoirs; however, the methods do not always give the desired stimulation effect. Thus, there is a demand for new cost-efficient technologies. In this thesis, Radial Jet Drilling (RJD) stimulation technique is investigated in order to contribute to the economics of energy recovery from chalk reservoirs in a more controlled and affordable manner than those conventional methods used in the industry as fracturing and acidizing.

The RJD technique is based on drilling multiple lateral boreholes from the main bore, in which a power of focused jet from a small orifice of the nozzle is used to break down the rock enabling a deep penetration into the formation. An important economic aspect of the RJD technology is the sustainability of the increase in production. To maintain the improved production rate after jetting, it is important to study and evaluate how rock properties and deformation behaviour change under varying confining stress, pore pressure and temperature conditions hence influencing the stability of jetted laterals.

The outcome of this project is based on three main parts: 1. jet drilling experiment; 2. rock mechanics testing; and 3. numerical modelling. Jet drilling experiments enabled us to identify the correlation of the operational performance of this technique and the rock mechanics properties, such as strength, stiffness and permeability. By means of rock mechanics testing, it was found that depending on the fluid type and conditions of the confinement during jetting, the rock mechanics properties can be altered. Lastly, based on numerical simulation of the borehole stability in the Gorm chalk field, the laterals can serve without instability concerns up to a year. However, in the long run, depending on the operational conditions of the reservoir, such as drawdown rate, depletion, how aggressive the shut-in and shut-down processes, among others, the stability of the hole may deteriorate. The feasibility study of RJD technique can be concluded as a viabile technique to be applied in the chalk reservoirs.

Principal supervisor:

Dr Hamid M. Nick, DTU DHRTC



Helle F. Christensen, GEO

Dr Saeed Salimzadeh, DHRTC


Prof. Christopher James Spiers, Utrecht University, the Netherlands
Dr. Edvard Omdal, ConocoPhillips, Norway


Dr. Michael Welch, DTU, DHRTC



Thu 06 Feb 20
13:00 - 16:00


DTU Compute
Center for Olie og Gas - DTU


Technical University of Denmark, DTU, Building 101, Auditorium M1