| The Ha-76 faulted-block reservoir of Er'lian Oilfield belongs to medium temperature (74℃), low-permeability (the average permeability is 25.3×10-3μm2) oil reservoir. There are many problems existing in Er'lian Oilfield H-76 faulted-block reservoir, such as the difference of physical properties are evident., poor development effect, poor well pattern adaptability, large vertical production and injection of fault block, the inconsistencies between formations are obvious and so on, thereby the degree of reserve recovery is not so high, by December 2004, the degree of reserve recovery was only 5.76%. Now, for H-76 faulted-block reservoir of Er'lian Oilfield, the daily fluid output is 117.7t, oil production per day is 9.3t, oil recovery rate is 0.15%, cumulative oil production is 18.7821×104t, cumulative water production is 27.0990×104m3. Sine the fault block has been put into development officially in June 1995, acidizing, sand fracturing, profile control, long cyclic water flooding and other measures have been adopted in succession to change the low level efficiency development condition of oil field, which not only achieved a certain effect to a certain degree, but also played the function of slowing down field decline, yet it can't change the low efficient production condition of oil field.In er'lian oilfield condition, According to acquiring the system composition of weak gel of deep profile control, gelling mechanism and mechanism of oil displacement etc, it is selected that weak gel profile control system of temperature resistance, salt resistance and organic crosslinking, thus it gives weak gel deep profile control and flooding plan, the scheme will be given after the construction for preliminary analysis. in this paper, the main recognition can be concluded as follows:1,Weak gel, a kind of weak gelation system with three-dimensional structure, is composed with low concentration polymer and cross-lingking agent, in which the intermolecular cross lingking is mostly and the intramolecular cross linking is secondary. It is an important technique in EOR, because it has dual effects that are profile control and oil displacement.2,The modified-natural-macromolecular starch, which has many advantages, such as temperature resistance, salt resistance and good resistant to shear. It is hardness and softness ,and it's structure make it hard to undergo thermo-oxidative degradation. All of its advantages make it can be used to deep profile control and flooding in H76 faulted-block oil reservoir.3,The weak gel system is choosed out for er'lian oilfield: polymer 1250 mg/L～2000mg/L, resorcinol 300mg/L～500mg/L and urotropine300mg/L～500mg/L. The system has good gelling performances, and the greater the system concentration is, the higher the gelling viscosity is.4,It has also researched the saline and thermal stability, injection property, ageing stability, resistance factor, residual resistance factor, and so on. The injectivity, plugging performance and sweep efficiency of the gel system is evaluated through core experiments. Lab Experiment results indicate that weak gel has caused apparent sealing effect on high permeability core after gelling, which finally indicates the purpose of profile control. So it can meet requires of er'lian oilfield.5,Modified-natural-macromolecular starch can be use to gel deep profile control and flooding plan in H76 fault-block oil reservoir ,After the effect evaluation result analysis, the results show that 11 corresponding connected oil well'fluid production by rise 148t/d original gradually 104.77t/d , and oil producing capacity by rise 13.28d/t original gradually 7.55t/d. the integral water content is down to 81.3% by 90.7%. According to gel deep profile control and flooding ,oil-generating peaks reaches to 5.5 t/d, the average single well potential is up by 0.7t120t, water rates were reduced about 9.4%, improving intake capacity between the layers and expanding swept volume effectively to improve water drive recovery factor. |
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