Comprehensive Management for Low-permeability Sandstone Oil Reservoir in Huoshaoshan Oilfield
Authors: Liu Bangcheng , Xu Xuecheng , Wang Guoxian , Qin Xuxian 
Published: December 2007

HuoShaoShan Oil-Field has been developed since 1987. It is a fracturedanticline sandstone oil pool with low-permeability. With the serious waterbreakthrough and water encroachment, the average decrease rate of productivityfor early years was as high as 22.7%. In the third year for development, thewater cut was 52.2% and the recovery percent of reserves was below 5%.

Up to now, so much testing has been performed, such as three recoverytechniques testing, testing of two wells for sealing core drilling, sevenplugging agent testing, two separate injection pipe strings testing, threeacidization methods testing, two leak protection pipe strings testing, downholedischarge dissolution test, high-engine-gas fracture testing, and test ofcompound perforation. At the same time, 59 wells have newly been drilled. Besides, profile control has been done in 37 wells, and the treatment ofFracturing, acidization, cement squeeze and water shut-off have been performedin 281 well times. After these treatment, by now, the net increment of the oilin the field is 7.28×104t and water cut in Huoshaoshan Oil-Fielddecreased from 55% to 40.3% and maintained at 53.4%. The degree of water-drivecontrol has increased from 51.1% to 68.2%.

After several years' comprehensive management, the poor effect has beenimproved, which achieved good economic benefit.

Introduction

HuoShaoShan Oil-Field is located in the north ZhangBei uplift of eastZhunGaer Basin in XINJiang China. The geological construction, which theoil-field located in, is an asymmetrical anticline with 20 degree ofstratigraphic dip in the east and 6 degree of stratigraphic dip in the west(Fig. 1).

PingDiQuang formation in Permian is the oil-bearing sequence. It is afan-river delta deposit with lithology of medium sandstone, fine sandstone, siltstone, argillaceous siltpelite, siltpelite, shale and dolomitic mudstone. Medium sandstone and fine sandstone are the best oil bearing sequence of theoil-field, and siltstone is better oil bearing sequence.

There are many types of pore structure in reservoir, such as intergranularpore, intragranular pore, intercrystalline pore, solution pore and fracture. From them, the secondary pore of intergranular pore and intragranular pore arethe dominant pore. The pore has the characteristics of narrow throat and lowpore throat coordination. From the top to the bottom, the porosity graduallyincreases.

Permeability of matrix material gradually increases from the top to thebottom, while effective permeability decreases from the top to the bottom. Allof these indicate that the growth degree of the fracture in the reservoir isgetting weaker from the top to the bottom. However, the permeability(3.75×10-3µm2) of matrix material is far less than theeffective permeability (162×10 -3µm2) of it, indicatingthe dominant function of the fracture during the course of seepage flow.

The data of capillary pressure and mercury injection have thecharacteristics of high-expulsion and higher mercury saturation, indicatinghigh growth degree of the fractures in the reservoir. Meanwhile, curves ofphase permeability have a narrow shared area, and water permeability increasesslowly. All of them reflect the characteristics obviously, (Ref.4, Ref.5).