The application of steranoid fingerprint compounds in the calculation of the single-layer productivity of heavy oil commingled producing wells in the Qinhuangdao 32-6 oilfield

摘要

The Qinhuangdao 32-6 oilfield is currently mostly a two-layer combined production well, so it is urgent to clarify the contribution of single-layer productivity to carry out targeted production measures. However, because the target formation is composed of heavy oil, it is impossible to carry out conventional liquid production profile logging. Using Ng1 and Ng2 as examples of two layers of heavy oil combined production wells, this paper combines two single layers of heavy oil with different weights in the laboratory. Fingerprint compound parameters with good linear relationships to the mixing ratio of crude oil were validated and screened by examining the whole-oil gas chromatography-mass spectrometry results using chromatographic principles for reference. The results show that the ratio of 5 alpha(H),14 beta(H)-homopregnane/5 alpha(H),14 beta(H)-pregnane has a very good linear relationship with the mixing ratio of crude oil, in which R-2 = 0.997. The contribution ratio of the single-layer productivity of 8 heavy oil wells produced by Ng1 and Ng2 is calculated according to the established chart. Combining dynamic production monitoring, logging interpretation and seismic inversion results, it is confirmed that the water shutoff in a high producing aquifer can effectively reduce its oil production ratio. The Ng2 sand body of the A25 well with relatively poor physical properties contributes less to oil production; however, because of the large size of the sand body, the effect of the fracturing transformation is better. Comprehensive research shows that sand bodies with better connectivity and greater thicknesses are the main contributors to productivity and will be the focus of future research. Fracturing effect research should be carried out to improve the productivity contribution ratio in sand bodies with relatively poor physical properties. The results of this study provide a scientific basis for monitoring the production performance of oil wells, for stratified reservoir management and for determining the future steps of two-layer combined heavy oil recovery wells; in addition, the results of this study provide a new geochemical calculation method for the single-layer productivity contribution of heavy oil two-layer combined production wells because conventional liquid production profile logging technology cannot be implemented.