Well Testing has been the subject of research for many decades. Well Testing are performed in order to estimate reservoir properties. These estimations are needed to determine the amount of damage that happen to the well during the drilling or in the production life. In this research the focus on evaluating the reservoir damage after the drilling and production in two different cold and thermal wells in the same field. The reservoir well testing interpretation includes number of steps to be finalized. It's running starting from data gathering, initialization and quality control. This book will be on field study (real data) from Fula North East (FNE) field located in block 6 Sudan. This study base on two wells (X) and (Q) . Well (X) is cold production well and well ( Q) is thermal production well. Data from FNE field have been gathered and the chosen key well is well(X) have been analyzed. Performing of well testing using conventional methods, derivative method and the simulation case is introduced. The methods is used to improve the well understanding and the field to decide about future work over strategies base on it by comp