Chemical Additives for Improving Compatibility of Drilling Fluid, Completion Fluid, and Other Well-Treatment Fluids for Deepwater Wells

Abstract

In deepwater completions in the GOM, synthetic-based mud (SBM) has been widely used for drilling the reservoir section. With increasing well depth and higher reservoir pressure, higher-density drilling fluids are used more and more often. It has been observed that with increasing density of drilling fluid, the incompatibility between drilling fluid, completion fluid, and other well-treatment fluids can cause more problems to drilling and completions. Consequently, the incompatibility can reduce the effectiveness of well completions and result in lower production. Often, the formation damage caused by the incompatibility can be very difficult to remediate. We have identified incompatibility between drilling fluid, completion fluid, and other-well treatment fluids for many GOM wells in lab studies. Chemical additives were studied for preventing the incompatibility between drilling fluid, completion fluid, and other well-treatment fluids. Chemical additives selected from lab study have been applied to many GOM wells, and their use has resulted in improved well production and has prevented catastrophic damage to the wells. We developed proper lab test protocol to subjectively evaluate chemical additives that can prevent or minimize incompatibility between drilling fluid, completion fluid, and other well-treatment fluids. The application of the selected chemical additives on several GOM wells will be discussed. This paper will summarize the lab test methods and lab test results based on testing for several GOM wells. It will also summarize the end results of well performance with the application of these chemicals.

Drilling Fluid Technology for the Third Interval of Sunan 23-113H2 Well

“…When the drilling fluid circulates in the wellbore, with the increase of density, the liquid injection pressure will increase, if the quality of the mud cake is poor, the water loss is large, the filtrate pressed into the formation is gradually increasing, exacerbating the collapse of the debris formation prone to collapse, so while increasing the density of the drilling fluid, it is necessary to reduce the water loss, the medium pressure water loss control is less than 3.0 mL, and the high temperature and high pressure water loss is less than 12.0 mL [11,12]. .494 Through the above calculation, the displacement plays a decisive role in the size of the annular air pressure consumption, so when drilling normally, the annular air return speed can reach more than 1.2 m/s, and the displacement is 12-13 L/s.…”