Research On Development Effect Of Ordovician Reservoir In12th Middle Block Of Tahe Oilfield

The District12reservoir in Tahe oil field is a ultra deep buried fracture-cave oil reservoir, its buried depth reaches as deep as5800m-6500m.With high heterogeneity, and the heavy oil in it, the crude oil average dynamic viscosity is as high as8067mPa.s(50℃). The oil-water relationship is very complicated, and development for oil is very difficult. After the reservoir entering phase of high production, the reservoir enters phase of stable production. The water ratio of some wells rise, and the production decrease is rapid. The measures for stable production and water control are actively implemented in order to stabilizing development condition.In view of prospecting and development present condition of the middle District12, with the well drilling、well logging、testing、development dynamic data and so on, based upon individual well reservoir identification and fluid identification, analyzed the type of water breakthrough and its affecting factor, analyzed the type of production decrease and its affecting factor. Through analyzing water injection、acid fracturing、indenter and water plugging, proposed the measures of control production decrease and water ratio rise. Get the main recognition as follows:1.The breakthrough well mainly refers to the type of water ratio rising slowly、 water ratio rising rapidly in the early and water ratio rising rapidly in the late. The main effect of the breakthrough well type include:the oil well of drilling or acid fracturing fracture-cavity displays water ratio rising slowly; the oil well of drilling containing water fracture-cavity causes water ratio rising rapidly; the oil well of acidizing reservoir of fracture-cave and fracture easily causes water ratio rising rapidly.2. By analyzing the reservoir and development behavioral characteristics of fracture-cavity unit TH12201and the fracture-cavity unit TH12330, the reservoir of fracture-cavity unit TH12201is well-developed and rich oil; the reservoir of fracture-cavity unit TH12230is poor, because of water breakthrough a part of oil well have low production. Basing upon the above analysis and combining the classify principle of fracture-cavity unit, the oil/water contact of fracture-cavity unit TH12201locates in the6303.5m, the fracture-cavity unit TH12330has oil/water contact respectively.3. The production decline of multiwall fracture-cavity unit is slower than singlewell, most oil well can long maintain high productivity. The production declinemainly affect by reservoir、natural depletion oil recovery and water breakthrough.4. By analyzing the measures for stable production and water control includewater injection、acid fracturing、indenter、water plugging and so on, and basing uponthe research of reservoir characterization、reservoir fluid characterization、waterbreakthrough characterization and deliverability characterization, proposed themeasures of control production decrease and water ratio rise:(1) In view of the well of fracture-cave and fracture is injected water slowly andthe shut-in time must be long, which make oil and water replace fully; In view of thewell of closed constant volume reservoir must be injected water before closing time.(2) The reservoir of fracture-cave and fracture going through acid fracturingeasily breakthrough, oil-water distribution characterization should be recognizedclearly before acid fracturing, averting oil well fast breakthrough cause flooding.(3) In view of the different reservoir characterization, choosing advisableinjection flow rate; the time of shutting in be not too late, when coning water is closeto bottom of a well should be shut in; the time of shutting in cannot be too long and bechose10-20d.(4) In view of the different reservoir development and breakthrough well type,combining production log data, adopting effective blocking off technology.