Research On Oil/water Relations Of Ordovician Reservoir In North10th Block Of Tahe Oilfield

This paper based upon practical condition of the northern District10,with thewell drilling、well logging、core、testing、development dynamic data and so on,individual well reservoir identification and fluid identification have been made. Fromthe individual well oil/water relationship extend to the oil/water relationship of welltie and the oil/water relationship in the whole plane,get the main recognition asfollow:（1）The space of ordovician reservoir in Tahe oil field is consist of cave、cavityand fracture. Huge cave is the main space，while fracture is just for communicationfor its capacity of reservoir space is limited. Fracture-cavity reservoirs could bepredicted effectively by using technology of wave impedance inversion and varianceratio of amplitude. The key point of high and stable yields in oil wells is whetherdrilling to caves or fractures communicating with cave, the development offracture-cavity reservoirs is controlled by the effect of depth and the developmentdegree of structure/fault.The fracture-cavity reservoirs developed stronger closer tothe top of erosional surface. The distributions of the fracture-cavity reservoirs on theplane mainly include northwestern and northeastern, the location are near fracturebelt.（2）The original oil-water distribution divided into three: oil producing profile,oil-water producing profile and water producing profile. The breakthrough well aremainly divided into three types: the type of water ratio rising rapidly and the type ofslowly decline of water ratio which is not output of formation actually belongs todrilling leakage or the output of fracturing liquid. So is in one same fracture-cavityunit, but there are several fracture-cave units regionally, and each has oil/watercontact respectively, neither is in the whole area or the fracture zone divided atpresent.（3）Water and oil mostly exist in the inner of the fracture-cavity unit, the distri-bution is controlled by the distribution of large fault and ancient erosional surface.Studies show that there is more oil and little water within the realm of100m under fracture-cavity reservoir in the north10th block, while there is more water andlittle oil beyond it, the percentage of oil formations is to93%within the realm of100m under the. erosional surface. Moreover the distribution of oil bodies is leadedby large fault, large oil body distributes in the district of large fault.The degree of oilbody filling is low,the oil saturation is low also, while the development degree ofwater body is good, the probability of drilling to water body or water output quickly islager in the district of bad degree fault development.