Abstract: A method of producing images of the limits of a geologic reservoir from measurements of fluid pressure in a well controlled to produce from the reservoir at a constant flow rate. The measurements are taken over a period of time, which includes initiation of well flow and recorded in a plot of well pressure v. time. The method includes detecting abrupt changes in slope of the pressure v. time function, where each abrupt change signifies the arrival of a primary shock wave at a discrete section of a boundary limit of the reservoir; and calculating the minimum radial distance to the discrete section from the well bore as a function of wave travel time. The changes in the slope of the pressure v. time function are used to calculate the curvature of the boundary at the minimum radial distance.

Abstract: A seismic mass 41 is supported by a beam 37 which has opposite ends secured to a housing 11 so that its gravity center G is positioned away from a straight line connecting the opposite ends the beam 37. Thus, a rotating force is given to the seismic mass 41 in response to an acceleration. The rotating force given to the seismic mass 41 causes displacement of the beam 37. Then, a capacitance between a movable electrode 43, 45 and a fixed electrode 21, 23, 25, 31, 33, 35 changes, and such a change defines a magnitude of the acceleration.