Sigra Pty Ltd
Engineering in Brisbane

We know the key parameters that need to be encourage for each reservoir and have the tools to determine them, whether for the gas or the mining industry. This includes testing for directional permeability and determination of how the permeability will change with production. This labor may precede to groundwater production, dewatering for mining, or the determination of water production into coal seam gas reservoirs. The test methods involve pumping from or injecting into a healthy and measuring the pressure change in that well or in surrounding monitoring wells during the flow and recovery periods. Effective stress changes close the well bore changing the permeability of the formation. In the case of coals it is plausible to under the pressure for a lengthy enough period that gas is desorbed from the coal. The analysis of such a test with observation wells is straightforward but for the case where the test is totally conducted in the producing well, a varying flow rate complicates the determination of imminent well bore effects. The volume of fluid is determined by the pressure change of the fluid in the string and by the measurement of gas flow at surface. In coals it is generally found that there are important near healthy bore pressure losses which unkind that the inflow rate to the healthy is governed more by these effects rather than the permeability of the coal seam. The test process involves pumping fluid into a test zone at enough pressure and rate that the reservoir is fractured. This involves emptying segment of the liquid from the drill string, sealing the test zone, waiting for pressure stabilization and then opening a valve between the test zone and the drill string to induce flow. Pressure transducers monitor pressure in the test zone, overhead the valve in the drill string, and packer pressure.Packer inflation is from either a water pump at surface or in shallower holes by thick air. It also contains high and low flow gas meters to measure the flow rate of gas from the drill string. The monitoring wells are fitted with pressure transducers either set between packers or cemented in place. Underground tests to determine permeability and pressure are generally conducted for water in all mines, or gas in coal mines. The Gas initially in Store is either measured directly, or via pressure. This actually models resorption through the changing pressure in the borehole as the core is retrieved and during the period on surface when gas is being lost from it. The process is to take core directly from the core barrel and to place it in a water filled pressure vessel. The reasons for undertaking such labor are generally do determine the need for or effectiveness of mine drainage for water or gas. As liquid pressure is a component of effective stress sigma has a number of techniques for measuring fluid pressure in rock. sigma also conducts surface stress measurement to determine the state of stress on the walls of excavations. While the above three techniques are for measuring stress at depth, sigma also undertakes surface and imminent surface stress measurements. To enable this sigma has various techniques for measuring fluid pressure in rocks. These techniques can be old in boreholes drilled from surface or underground.