Observation of Induced Fractures Intercepted by Mining in the Warrior Basin,Alabama. Topical Report. Rock Creek Methane from Multiple Coal Seams Completion Project

摘要

This report summarizes research and inspection of induced fractures that havebeen intercepted by mining. Induced fractures from 13 wells intercepted by mining were inspected at the Jim Walter Resources' (JWR) No. 4 and 5 Mines in Tuscaloosa County, and the Oak Grove Mine in Jefferson County, Alabama. In this area the Mary Lee and Blue Creek coalbeds average 1.3 ft and 4 to 5.5 ft, respectively at depths of about 2,000 ft at the JWR mines and 1,000 ft in the Oak Grove Mine. These seams are usually separated by 2 to 10 ft of rock parting. The wells were completed open hole from 1982 to 1986. Hydraulic fracture treatments were used to stimulate production. Some expected results include: in general, the fractures followed the coal face cleat direction; they were vertical, and were sandpacked close to the wall. Other observations include the following: (1) most of the fractures and proppant were present in the parting and roof rock, (2) results were similar in the JWR and Oak Grove Mines even though there is 1,000 ft less overburden at the Oake Grove Mine, and (3) no horizontal fractures were observed in the study; though other stimulations have propagated horizontal fractures at Oak Grove.