Abstract
For the last decade, the global trend in the oilfield industry is to improve the oil and gas production by drilling as well as by completing horizontal wells and later on, improving the process using multistage fracturing. Though the number of horizontal wells is rapidly increasing, the production of hydrocarbons is not always up to the designed volume. In this regard, acquiring the knowledge on the performance of producing intervals is an important task for operating companies to fully optimize the productivity and maximize the recovery as well. Production logging solutions proved to be efficient in vertical wells, however, encountered various challenges in horizontal laterals as the logged section is often more than 20 times longer compared to vertical wells [1]. Common factors that complicate the production logging are layered flow of formation fluid, deviation and accessibility of wellbore, and changes in fluid velocity moving past or through the tools. Direct transfer of production logging technology and interpretation algorithms from vertical wells to horizontal wells leads to erroneous conclusions about the well performance [2]. Moreover, the quality of well completion and reservoir management decisions for production wells largely depends on the production logging data such as mechanical flowmeter and fluid capacitance surveys.
Until recently, there is no alternative to wireline downhole tools being used to evaluate the placement of fracturing proppant or acids, production rate and zonal water breakthrough. In practice, well intervention in horizontal wells requires implication of coiled tubing or tractor services to deploy logging tools downhole. The success of well intervention depends on several factors and among of these are as follows: well accessibility, completion IDs and length of the horizontal lateral, etc. There are also key aspects to be considered such as the significant cost of well intervention and the availability of wireline and coiled tubing equipment. This article provides an overview of one of the alternative methods of production logging in horizontal wells which doesn't require well intervention using PLT tools, Coiled Tubing or Tractor services. This method employs tracer technology of quantum dot markers placed in the reservoir during stimulation. The method also allows reducing the cost as well as the complexity of acquiring downhole data. Unlike the conventional PLT, the technology described below can provide production logs on demand during one year after well stimulation.
