Description of steam chamber shape in heavy oil recovery using 4D microgravity measurement technology

Abstract

4D microgravity measurement is used to study the underground medium, especially underground fluid variation state and process, using repeated measurements of gravity data at different periods. A model of microgravity variation calculation for the Guantao Formation in the Du 84 block of the Liaohe Oilfield was established according to the practical condition of the steam assisted gravity drainage (SAGD) of super heavy oil reservoir. The distribution of residual gravity that reflects the density change of the steam injection layer and heavy oil layer can be obtained using the target area 4D microgravity measured at different periods through wavelet transformation. With −20 μGal as the main anormaly, the variation of steam chamber shape in the steam assisted gravity drainage can be quantitatively described by analyzing the distribution of steam chamber, and drawing the steam chamber overlapping map of two observations. Numerical simulation and well temperature test verified the feasibility of the technology. The result from the technology can be used to adjust steam injection scheme timely according to the morphological changes in the steam chamber, for example, the Gh12 well has got good results, with oil production going up from 65.4 t/d in May 2010 to 82.8 t/d in May 2012 after adjustment of its injection scheme. Key words: gravity field, SAGD, microgravimetry, steam chamber