Scale inhibitor squeeze strategies in horizontal wells

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 problems which 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 operational experience 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.