Design and Application of Removable Plugging Slurry for Fractured Carbonate Reservoir
To meet the requirements of leakage stopping and reservoir protection at the same time in fractured formation, the removable plugging slurries with high temperature tolerance were designed, evaluated and applied in the field successfully. Analysis shows that the fibre materials can deposit onto crack surface, bridge and seal fractures quickly and the selected particles can bridge in throat near wellbore. The comprehensive grading of filling particles was determined from the point of view of gradient filling. The designed plugging slurries KJD155 and KJD200 with higher total dissolution rates sealed 1 mm, 2 mm, 3 mm, and 4 mm crack blocks effectively at room temperature and high temperature (KJD155 at 155 °C; KJD200 at 200 °C) respectively. Their pressure bearing ability of them was up to 5 MPa under bottom hole conditions, which was beneficial to the next operation. Field application of the designed plugging slurries was carried out successfully and showed that they were removable and did smaller damage to reservoir.
Rheological and Fluid Loss Properties of Water Based Drilling Mud Containing HCl-Modified Fufu as a Fluid Loss Control Agent
Investigation on rheological and fluid loss properties of water based drilling mud containing acid modified fufu starch is presented. Hydrochloric acid at 8% and 16% was used, aiming at improving fufu performance as a fluid loss agent under extreme drilling temperature of 300 F. Three formulations of mud weights of 75, 100 and 150 pcf were used, as proposed by the API and NISOC standards. Rheological properties, which are apparent viscosity, plastic viscosity, yield point and gel strength for the modified fufu showed significant improvement when 16% acid was employed. A significant amount of fluid loss reduction was obtained within light and average mud weights formulation (75pcf and 100pcf). Although none of the samples (modified and unmodified) meet the NISOC fluid loss standard requirement for the applied temperature, a great improvement was observed in ascending order of 16%HCl > 8%HCl > unmodified fufu WBMs, accordingly.
Finite Difference Modeling on the Temperature Field of Substrate in Friction Surfacing
Friction surfacing is an advanced process of great potential, especially in the field of repair and reclamation of worn and damaged components. As a kind of thermal processing technology, the temperature profile and changes of the substrate in friction surfacing are important factors to get coatings of high quality. In this paper, the temperature field of the substrate during the process is simulated by finite difference method. The results are consistent with experiments, reappearing the temperature change of the substrate during friction surfacing, allowing further study on figuration and quality of coatings.