Ann: XST: Drilling Break and Gas Peak at Guinda Sandstone - Borba, page-7

Drilling Break
What is a Drilling Break? When drilling a well, the rate of penetration tells the driller just how fast or how slow the drilling process is going. For example, if we are drilling at 50 feet per hour (15 meters per hour) and suddenly we start drilling a new section at 200 feet per hour (60 meters per hour), this sudden jump or increase in drilling rate is called the drilling break. Another name for a drilling break is a drilling jump.It is important to note, all things being equal, that the deeper we drill vertically into the earth, the harder the formations are because the overburden pressure from overlying formations increases with depth. Harder formations are more difficult to drill than less compact formations, which is why it is important to take notice when we suddenly begin drilling faster as we go deeper.
So you have to assume that we have entered a porous section. Hope this helps show how important this drilling break is,