Interference Analysis in Reservoirs with Bottom-Water Drive During Water Injection Processes Through Subsurface Connectivity

Abstract

This work analyzes the feasibility of implementing water injection processes through subsurface connectivity between different formations through communicating wells, allowing the water to flow from a source aquifer to a depleted formation. It presents a 3-dimensional semi-analytical model for estimating water influx in reservoirs with bottom-water drive and analyzing interference between reservoirs when subsurface connectivity is carried out to supply energy from an aquifer. It applies to both finite and infinite aquifers and reservoirs sharing an aquifer. The general solution is obtained by solving the diffusion equation employing Laplace and Fourier cosine transforms and is presented in Laplace space, requiring a numerical inversion method to convert the results to the real space. The functionality of the analytical solution is evaluated with reservoir numerical simulation and communicating well models. Results show that implementing this solution brings notable advantages because the ultimate oil recovery factor improves considerably. Additionally, it delays the water encroachment in reservoirs adjoined to the source aquifer and reduces water production.

Experimental and Statistical Study on Wellbore Scaling Mechanisms and Characteristics for Huanjiang Oilfield

“…Based on the experimental results from Table 1, the following conclusions can be drawn [1]: The formation water of deep Yanchang formation has a high content of scaling anions (HCO 3 -) and scaling cations (Ca 2+ ). During the uplifting process in oil depletion, the reduction of 6 Geofluids temperature and pressure leads to a large trend of inorganic scaling (CaCO 3 ) [2].…”

“…In addition, crystallized scales such as NaCl and KCl exist at all positions of the wellbore. According to the above analysis results, it can be concluded that the scaling characteristics of oil wells in the Huanjiang oilfield in different payzones are as follows [1] 7 Geofluids deposition scale, corrosion scale, and NaCl and KCl crystal scale [2]. The oil wells in the Yan'an group (Yan 6, Yan 7, Yan 8, Yan 9, and Yan 10) are mainly wax deposition scale and corrosion scale, and the calcium-based scale is greatly reduced compared with that in the Yanchang group.…”

“…Water injection is a mature and effective technology which has been successfully implemented worldwide. Although many oilfields have entered the tertiary oil recovery (EOR) stage, water injection to supplement formation energy and maintain formation pressure is still one of the basic measures for worldwide oilfields to ensure long-term stable production and improve oilfield development efficiency [1][2][3]. However, a series of production problems have been induced during the water injection process [4].…”