Multiphase Inflow Monitoring in Horizontal Wells Producing from Oil Rims Based on the Advanced Production Logging Suite Data

Abstract

Today, oil reservoirs with a gas cap on top are mainly developed by drilling horizontal wells of various design. In the course of well operation, early increase in gas-oil ratio or water cut can often be observed. These may be caused by both well integrity failure and the geology feature of the target formation when formation water breaks through from the bottom of the producing formation and gas inflows from the top of the reservoir as a result of coning. One of the ways of controlling unwanted water and gas production sources and reservoir fluid production rates is monitoring of production profiles along the horizontal sections of the well using a reservoir-oriented production logging survey. This paper describes an example of such monitoring at a horizontal well drilled into the oil-rim reservoir at the Novoportovskoye field. The paper provides the results of a series of logging surveys performed in 2, 18 and 24 months after the well commissioning. The first (reference) survey was performed at the earliest stage of the well production; the second and the third ones - when the gas-oil ratio started to increase. The advanced production logging survey included high-precision temperature logging, distributed capacitance measurements and spectral acoustic logging. The spectral acoustic logging data identified the producing intervals of the reservoir along the horizontal section of the well. According to the first survey results, the production fluid was flowing uniformly along the wellbore. The third and second surveys had identified the intervals of gas breakthrough in the reservoir. After all the survey results had been compared to one another, it was identified that the gas breakthrough could have been localized even during the first logging survey. In each survey, the multiphase inflow profiling was perfomed using a temperature modelling. Information generated as a result of production logging survey in the horizontal well allows localizing and predicting gas breakthroughs in wells drilled in oil rims. Using this data, such gas breakthroughs may be immediately prevented. The data can also be used when designing new wells to increase the efficiency of development of such fields.