Hypotonic Strong Water-sensitive Oil Reservoir Development Of Anti-expansion Process,

Reservoir of Che 2 district Qigu formation in Chepaizi field has low permeability and strong water sensitivity. Reservoirs of this type encountered more difficulties during development because its characteristics were quite different between low permeability and high permeability. As no precedent could be used for reference in Xinjiang field, we had the very same aim to develop this field effectively, enhance ultimate recovery and acquire the maximum economy benefit.This article mainly depicted the feasibility, techniques research, application and evaluation of water injection scheme in Che 2 district Qigu formation of Chepaizi field. Using three geologic theories, stratigraphic sequence, geostatisties and geophysical exploration, we performed high-accuracy 3D seism explanation and precise reservoir description to explain reservoir constitution, rupture, sedimentary phase, oil layer, reserves and oil water distribution. And finally we established 3D reservoir geologic model. Simulation researches of water injection feasibility were carried out with LANDMARK'S VIP4.0 black-oil simulator from such aspects as waterflood and natural recovery, different water injection well and intensity, and reservoir swelling prevention. The results showed that development of this field should base on water injection and it is better to inject earlier than later. It also shows that ultimate recovery rate was closely related to the permeability. So measures should be taken to prevent the reservoir from swelling to reduce the loss of permeability. Also, this article depicted the method to draw up the standard of injected water quality, educed the fracture-pressure and maximum injection pressure of the reservoir through theoretical research, proceeded protection and breaking down techniques research of water-sensing reservoir through indoor core experiment and in situ experiment, achieved effective measures to protect and break down water-sensing reservoir, and performed consistency and mode optimization research of the swelling resistant medicament using general method of reservoir engineering as well asindoor core physical experiment and in situ trail-injection. Based on indoor core experiment and without related waterflood information, Xinjiang Oil Field Exploration and Development Research Institute gave the advice of adding swelling resistant chemical GY-2 with 0.2% to injected water when waterflood is required for the reservoir, and only the cost of the chemical would reach ï¿¥57.6/m3. By indoor core experiment, theoretical research and in situ effect of trail-injection, we boldly address the step chemical injection scheme with the percentage 0.6%, 0.3% and 0.15%. In situ application results showed that due to this scheme, good antiswelling effect was achieved, injection cost reduced ï¿¥43.2/m3 and ï¿¥3,571,000 of injection cost were saved. Additionally, we addressed after research the measures of reservoir protection during drilling, completion and repairing, as well as effective measures of increasing production and injection.After 3 years' waterflood, the situation of Chepaizi field's production had been turned round. Exceeding from the lowest 215t/d to the end of 2001's 262t/d, production became stable and increasing in Chepaizi district. Natural reduction declined from 43% before injection to 2001's -10.1%, which indicated the good effect of waterflood. Also, it make known that the antiswelling techniques of waterflood and the measures of increasing production and injection were successful.