Study On Oil-water Relationship Of Carbonate Fracture-cavity Reservoir In Tahe Oilfield

Based on the previous geology, seismology, logging, testing data, and development performance, it has been studied in this thesis that the storage and their configure property, fluid distribution in fracture-cavity unit of Ordovician carbonate reservoir in Tahe oilfield. The oil-water relationship concept models have been established that can be used to interpret soundly development performance in typical fracture-cavity units. The development strategy has been brought forward to solve the water invading in development. Some achievements have been getting as below in this thesis:1. It's that cave and fracture constitute the fracture-cavity unit. The concept model of fracture-cavity unit can be descript by one or more large pipeline shape cavity systems formed in a periods or several different periods, communicated by nature and acidizing-fracturing fracture in Ordovician tight carbonate rock.2. According to oil-water output change after a well began to produce water, it can be classified product water character into slow, fast and intermittent product water type. Oil wells of slow product water type have a slow watercut rising and relative low watercut, have a longer oil-water production age, then turn to fast product water type. Oil wells of fast product water type watercut rises promptly that can be approximated to 90% in a short time. Oil wells of intermittent product water type is a special type, watercut may recede slowly after a period of oil-water production, and product oil again.3. In multi-wells fracture-cavity unit, not every well water production keeps to the law that consistent edge and bottom water invasion. There may be more than one water-body in a fracture-cavity unit; therefore it manifests water influx character of a spot or a local block. Through argumentation, it's considered that compartmental oil driving water is principal mechanism in the finite water body with feebleness energy. Water may invade into reservoir along the portrait fracture or cave corridors if there is a large water body under the oil body. It is difficult to make a directness certification of compartmental oil driving water while oil invading water like piston forwarding.4. By analyzing the results of the replacement oil by water injection about 30 units of single-well; an excellent injection effect can be getting in the fracture-cavity unit which is not production water. The replacement oil by water injection has hardly effective after a well has begun to produce formation water or injection water because water contact has reached to well hole in fracture-cavity unit.5. After oil production become low, the injecting water from the bottom of a unit can increase the oil production of wells upward, also can raise the oil-water contact, and prompt the water containing of the oil wells or oil-water wells upward. Bottom water injection in a multi-well unit also increases the energy of oil body from the reverse direction of the formation water invading, enhances oil body pressure, and reduces water containing, holds down water coning.