Scale Inhibitor Squeeze Strategies In Horizontal Wells
Authors: Sorbie K.S. , Wesselingh E.M. , Yuan M.D. , Lemanczyk R.Z. , Todd A.C. 
Published: March 2010

Much attention has been given to the drilling, completion and initial production stages of horizontal wells. The advantages of using horizontal well technology is well documented and many successful field cases-in terms of well productivity-have been reported. Much less attention has been given to some of the production problemswhich may arise when such wells start to produce water. In particular, there are a range of specific production chemistry issues which have not been widely discussed in the industry literature. The main reason for this is that, to date, there is very little operationalexperience with such problems.

In this paper, we consider the problem of carrying out scale inhibitor squeeze treatments in horizontal wells. If carbonate or sulphate scale formation occurs in a water producing horizontal well, we anticipate that the treatment strategy will be rather different from that which would commonly be applied in a vertical well. The authors are not aware of very much field experience which can be called upon for this type of treatment. We have therefore taken a conceptual design approach which tries to anticipate the problem and to plan ahead for its solution. A simulation and modelling study is presented in which various scale inhibitor treatment strategies are examined with a view to determining the main factors which affect this process in a horizontal well. We tackle a number of important questions which will face the industry as scaling problems are encountered in horizontal wells.

We present this work as a preliminary study which tries to highlight some of the issues, problems and questions which will arise in the future when more horizontal wells start to operate at higher watercuts. The objective is to raise these issues at this stage in order to stimulate some discussion within the industry about how scaling problems in horizontal wells will be solved, possibly by using squeeze technology. We do not solve all of the problems which we raise but a number of points emerge from our study which we present as a preliminary assessment of this problem.

Introduction

More and more current field developments are employing horizontal well technology in order to improve reservoir sweep efficiency, raise well productivity and to generally improve project economics(1). Indeed, many field developments would not be possible without the use of horizontal wells. The states of development of horizontal well technology might be broadly classified into the following three categories:drilling and completion,reservoir characterization and engineering andproduction operations and well intervention.

This order also represents the industry's decreasing level of experience, and hence knowledge, with the third category being some way behind the others(2). How much one might need to engage in the third area dealing with water production and stimulation depends on the specific company's view on how they wish to use horizontal wells. If no period of post-water breakthrough is envisioned, or if this period represents the abandonment time for that horizontal well, then clearly this matter is not important.