During the drilling operation of an oil or gas well, the drilling fluid is circulated through the drill string into the wellbore for removal of the drill cuttings and maintenance of the hydrostatic pressure to balance the formation pressure. Whenever weak, fractured, unconsolidated or low-pressured zones are encountered while drilling, there is an appreciable loss of this drilling fluid. This fluid loss or loss circulation is a major drilling problem as it results in not only drilling fluid loss and drilling operation interruption, it also adds up to the total drilling cost of the operation.
In order to counter this problem and to ensure a smooth operation, Loss Circulation Materials (LCMs) are used. Various LCMS have been designed and are being used in the industry. With better understanding of loss inducing zones and advancements in material sciences, new LCMs are appearing in the limelight. One novel method to tackle the loss circulation problem is the use of gel forming polymer systems; that would gel, set and seal the undesired thief zones thus preventing loss circulation.
In this work different polymer systems have been studied for their possible use as a loss preventive and sealing agent. The main component of these polymeric LCM systems comprises of hydrolyzed polyacrylamide (HPAM). HPAM enjoys a favourable position in many industries specially the petroleum industry because of its properties and economic viability. In this work interaction of a commercial grade HPAM/HPAM derivative with polyethleneimine (PEI) have been studied.
These studies involved the identification of the optimum polymer/crosslinker concentration and testing of their thermal stability. Dynamic rheology tests were conducted in order to examine the behavior of the systems pre and post gelation. The gelation kinetics of the systems was also studied through Differential Scanning Calorimetry (DSC).
To test the effectiveness of a suitable sample, a see through flow setup was developed. This system allows for the visual observation of the performance of the LCM system in a highly porous media.