Well Testing, Methods and Applicability

Abstract

Well testing is widely used today in water wells, oil and gas wells, for geothermal

applications, within civil engineering projects, thermal storage and CO2 storage. The overall

testing goal is to verify the productivity from a well and/or for characterization of hydraulic

and thermal properties, as well as the spatial limitations of an aquifer. There are three major

methods for conducting well testing; slug tests, pumping tests and injection tests. The main

objective of this thesis is to compare and evaluate the applicability of the three major well

testing methods, using experiences gained by active participation in several well testing

operations. Testing of shallow and very deep wells as injection tests using a complete tunnel

lining are compared and uniquely presented together in the same work. To compare and

evaluate the applicability of the three well testing methods, several conditions which govern

the selection of hydraulic testing methods are varied and these include, amongst others, the

location, depth and diameter of the well. In addition, technical constraints, such as logistics,

water handling and external power supply for conducting the testing are also considered.

Certain emphasis is also placed on the use and comparison of pneumatic slug testing with

other well testing methods, as pneumatic slug testing often complementary to the more

expensive and logistically demanding pumping and injection tests. A small diameter slug test

equipment was put together for evaluating the applicability of this method and applied in

three different geological environments, namely sedimentary deposits, volcanic deposits and

the crystalline basement.

It was found that knowledge of the applicability of slug tests, pumping tests and injection tests

is essential for selecting the most appropriate method. Two of the methods, namely pumping

tests and injection tests, are logistically demanding while the third one, slug tests, is easy to

execute. Consequently, it is therefore also an inexpensive test method, which is supported by

the fact that several tests can be conducted in different wells during the same day. Slug testing

using pneumatic initiation has also been demonstrated as a good alternative to pumping tests,

obtaining similar transmissivity estimates. An advantage of slug testing is that the

transmissivity is estimated from a series of slug tests and not from one single test, which is

often the case for pumping or injection tests. Slug testing using pneumatic initiation is often

associated with testing in small diameter wells, but in this work it has been shown applicable

in large diameter wells at least up to 12". A major advantage with pneumatic slug testing

compared with the other methods is that it can be used for transmissivity mapping, simplified

by the method’s easy logistics. It is a useful approach if the wells are distributed over a large

area. It is suggested that slug testing using pneumatic initiation should be used as a preinvestigation

method for civil engineering projects. Further work needs to be carried out for

explaining the observed non-linear characteristics in data obtained from some of the slug

tested wells.

It has also been demonstrated that well testing methods are not only restricted to drilled wells.

The methods can also be applied inside a tunnel with injection through the tunnel lining. The

testing was performed as step injection and constant head/pressure tests and, in conjunction,

the response from the testing was measured in observation wells drilled from ground level.

Analytical solutions developed for vertical wells could be used to interpret hydraulic

properties such as transmissivity, using injection tests performed at tunnel level and the

pressure response measured in two of the observation wells. Well development was found to

be of great importance for any type of well testing and, for deep wells, a hydrojetting system

using coiled tubing and simultaneous pumping was found to be applicable, successful and

time efficient.

• author: Rosberg, Jan-Erik
• supervisor: Leif Bjelm; Gerhard Barmen
• opponent: PhD Butler, James J. Jr, Kansas Geological Survey, The University of Kansas, USA
• organization: Engineering Geology
• publishing date: 2010
• type: Thesis
• publication status: published
• subject: Geotechnical Engineering
• keywords: slug tests, well completion, re-injection, Well testing, pumping tests, injection tests, well development, pneumatic initiation, hydro-jetting, coiled tubing, tunnel lining, deep wells
• pages: 164 pages
• defense location: Lecture hall B, in the V-building, John Ericssonsv. 1, Lund University Faculty of Engineering, Lund
• defense date: 2010-06-04 13:15:00
• ISBN: 978-91-976848-3-5
• language: English
• LU publication?: yes
• id: c5290f15-aa57-4d79-b593-f29cdc3a28d5 (old id 1598933)
• date added to LUP: 2016-04-04 11:34:23
• date last changed: 2018-11-21 21:05:44