Can Proppants Do More Than Hold The Fracture Open?
In the 1940’s experimental fracture treatments were performed without proppant. However in most formations unpropped fractures heal quickly with no sustained benefit, and in 1947 river sand was introduced as proppant. The first evolution in proppants came in the 1950’s, when river sands started to be replaced by higher quality mined sands from Illinois and Texas. This was the early recognition that employing more uniform, rounder, stronger - and ultimately more conductive proppant - produced larger production gains. From this point on efforts concentrated on improving sand performance and finding new propping materials that could cope with harsher conditions. In the 1960’s, petroleum engineers incorporated walnut hulls, glass and plastic beads into frac designs. The 1970’s saw the introduction of resin coated proppants and the first commercial bauxite based ceramic proppant, followed by low and intermediate density ceramics in the 1980’s. However, throughout this time, proppants still served one primary purpose – to prop open the fractures and provide a conductive flowpath for hydrocarbon production.
Placement of proppant deep into the formation brings a unique opportunity of conveying new functions, additional to the primary roles of keeping the frac mechanically open and providing a conductive path for production enhancement. For decades most proppant development efforts concentrated on developing proppants that could either cope with higher stress and deliver higher conductivity or improve proppant transport via lower density, while minimal effort was put in adding other functionalities. Recently it has been recognized that other functions can be incorporated into manmade proppants during the industrial manufacturing process, thereby exploiting the placement opportunity. These functions might include assuring flow in the production system, providing reservoir surveillance or monitoring fracture properties.
This paper will review the latest technology developments that enable the incorporation of these functions into proppants, including how the new proppant delivered technologies permit users to cost effectively deploy additional functionalities in the initial completion of hydraulically fractured, frac-packed and gravel-packed wells. The paper will also present recent case histories of field implementations of these technologies which illustrate how these high function proppants can reduce overall operating costs, enhance production and diagnose hydraulic fractures.