Modeling Scale-Inhibitor Treatments in Horizontal Wells: Application to the Alba Field

Abstract

Summary Many horizontal wells produce both oil and brine for an extended period of time and, therefore, in many cases the problem of mineral scale deposition must be solved. Scale management in long horizontal wells faces several challenges, a major one being the correct placement of the scale inhibitor slug in the formation. Accurate placement is required to ensure that vulnerable well sectors are treated, without wasting chemical in the protection of zones which will not cut water during the lifetime of the squeeze treatment. This paper presents results from a novel nearwellbore simulator (assist2), which is used to model scale inhibitor treatments in horizontal wells. A technique for modeling such treatments has been developed which gives an improved understanding of where the chemical will be placed under different injection strategies, and how the placement will impact the squeeze life. It also allows the engineer to assess the impact of varying such parameters as inhibitor slug volume and concentration, overflush volume, injection rate, etc. Different inhibitor chemicals can be compared for their performance under the given reservoir conditions. This technique has been applied to model a squeeze treatment in a horizontal well where good production data are available. Connection oil and water flow rates, calculated by a full-field simulation model, have been matched by assist2. Various treatment designs were tested to assess the impact of the controllable parameters listed above. Findings enabled a treatment to be specified that was predicted to increase the squeeze lifetime without increasing the volume of chemical required. This modeled application strategy will also reduce the initial inhibitor concentration spike in the return curve. The performance of various chemicals under reservoir flow conditions was modeled, with a clear best choice emerging from these studies. Based on the findings of this modeling work, recommendations were made for a squeeze treatment, which were implemented, and the resulting field data are presented.