CAJ | 학술논문

疏松砂岩油藏在开发过程中由于地层压力下降会对储层产生损害，影响油井产能，需要对储层再压实作用下的物性及油水两相的渗流特性进行研究。首先采用储层压力条件下的连续测试方法，以恒定的驱动流速、变化内压的方式测试了储层岩心在再压实作用下的物性，从宏观角度分析了疏松砂岩再压实作用下的物性变化规律；再通过压实作用下的压汞试验，从微观角度阐述了疏松砂岩的孔隙结构演化特征；最后通过压实作用下储层岩心的油水流动试验，分析了压实作用下油水两相的渗流特性。疏松砂岩的渗透率随着再压实作用增强持续降低，降幅达53％左右，在孔隙度约降低7％时，岩石中相当大部分孔隙在压实作用下蜕变成喉道，孔喉体积比由1.50增至1.96，峰值对应孔径降至压实前的50％，造成渗透率下降幅度远超过孔隙度下降幅度；随着再压实作用增强，油、水两相的渗透率约降低50％，残余油饱和度由17.8％增至19.2％，束缚水饱和度由18.5％增至21.2％。研究结果表明，随着再压实作用增强，疏松砂岩的孔隙和喉道均被压缩，导致储层物性变差，而孔隙度的降幅相对较小，渗透率呈幂函数下降，降幅明显且在地层压力恢复过程中无法恢复；束缚水饱和度和残余油饱和度随有效应力增加呈指数上升，油相渗透率随有效应力增大呈线性下降，这就是在注水不及时或注水不足的区域油井产能大幅度降低的主要原因。
소송사암유장재개발과정중유우지층압력하강회대저층산생손해，영향유정산능，수요대저층재압실작용하적물성급유수량상적삼류특성진행연구。수선채용저층압력조건하적련속측시방법，이항정적구동류속、변화내압적방식측시료저층암심재재압실작용하적물성，종굉관각도분석료소송사암재압실작용하적물성변화규률；재통과압실작용하적압홍시험，종미관각도천술료소송사암적공극결구연화특정；최후통과압실작용하저층암심적유수류동시험，분석료압실작용하유수량상적삼류특성。소송사암적삼투솔수착재압실작용증강지속강저，강폭체53％좌우，재공극도약강저7％시，암석중상당대부분공극재압실작용하세변성후도，공후체적비유1.50증지1.96，봉치대응공경강지압실전적50％，조성삼투솔하강폭도원초과공극도하강폭도；수착재압실작용증강，유、수량상적삼투솔약강저50％，잔여유포화도유17.8％증지19.2％，속박수포화도유18.5％증지21.2％。연구결과표명，수착재압실작용증강，소송사암적공극화후도균피압축，도치저층물성변차，이공극도적강폭상대교소，삼투솔정멱함수하강，강폭명현차재지층압력회복과정중무법회복；속박수포화도화잔여유포화도수유효응력증가정지수상승，유상삼투솔수유효응력증대정선성하강，저취시재주수불급시혹주수불족적구역유정산능대폭도강저적주요원인。
The formation pressure of unconsolidated sandstone reservoir drops in the development process which damages the reservoir and affect oil well productivity .It is necessary to study the physical properties and seepage characteristics of unconsolidated sandstone under re-compaction .First ,a continu-ous testing method was adopted to measure the physical property of pay zone core under re-compaction in the way of constant driven flow rate and variable inner pressure ,the variation laws of physical properties of unconsolidated sandstone under compaction w ere discussed at the macroscopic level .T hen the evolution characteristics of the pore structure were further elaborated under compaction from microscopic point of view through mercury penetration experiment .Finally ,the seepage feature under compaction was studied by the fluid variation experiment .The permeability of unconsolidated sandstone was reduced continuously with the enhancement of re-compaction ,which represented a decline of 53% .When the porosity was re-duced 7% or so ,a majority of the pore was transformed into pore throats under compaction ,the pore-throat volume ratio increased from 1 .5 to 1 .96 ,and the pore radius corresponding to peak value reduced to 50% of the original value ,w hich caused the permeability to decline permeability more than the porosity . With the continuous compaction ,oil-water two phase permeability reduced to nearly 50% ,the residual oil saturation increased from 17 .8% to 19 .2% and irreducible water saturation increased from 18 .5% to 21 . 2% .The research results show that with the increase of compaction ,the pore and throat of unconsolidated sandstone are all compressed ,leading to poor reservoir physical properties ,and w hile the porosity drops slightly ,the permeability drops in a power function ,and the permeability was not recovered in the process of formation pressure recovery .Irreducible water saturation and residual oil saturation increase exponen-tially with the increase of effective stress ,and oil phase permeability is linear downward with the increase of effective stress .Consequentely ,this is the cause of decrease of oil well productivity due to insufficient water injection or injection water delay .