TECHNICAL COUNTERMEASURES OF RESERVOIR PROTECTION DURING THE COURSE OF DRILLING IN DAQING PERIPHERAL OILFIELD

In order to optimize the effectual reservoir protection techniques with low costs during the drilling process, the damage appraisement experiment of drilling fluid and screening out experiment of reservoir protection techniques are carried out in four blocks of Daqing peripheral oilfield. According to the experiment data of the core solid phase damage degree, liquid phase damage degree and overall damage degree from different kinds of drilling fluid systems, the reservoir damage degree by three kinds of drilling fluid systems commonly used in Daqing peripheral oilfield is obviously. Experimental results indicate that the damage of the low permeable reservoir by drilling fluid is serious, the extent of damage is up to 64.54%, and rely mainly on the fluid phase damage. The keystone of the reservoir protection in low permeable oilfield is to reduce the filter loss of the external fluid. From the screening out experiment of reservoir protection we can see that the modified drilling fluid with fluid inhibitor introduced can reduce the core damage degree by 20.04%, ultra fine calcium carbonate temporary plugging technology can reduce the core damage degree by about 5%. It proves that both techniques have achieved the goal of reservoir protection.