The RPD-4S equipment is designed to study the geo–environment in the inter-well space (the RVP method) located between two wells - the radiating and receiving ones.
The purpose of studying the inter–well space is to solve problems of geological content, first of all, to determine low-resistance productive inclusions in a relatively high-resistance host medium.
The basis of the equipment consists of two controlled downhole devices: the emitting and receiving ones, which generate and receive a signal at probing frequencies.
The operation of the complex is carried out under the control of an operator who sets the sensing parameters on a control laptop located in the logging station. Communication between the transmitting and receiving wells is organized via a VHF radio channel
Each projectile is equipped with an electric antenna (an electric dipole) with a plumb line.
To eliminate the "antenna effect", an optoelectrode isolation unit is used in each logging projectile – both in the emitter and in the receiver and +12V batteries for the emitter and +9V batteries for the receiver are used to power the projectiles.
The receiver is implemented according to a heterodyne scheme with two quadrature channels. Digitization of IF signals is carried out using 16-bit ADCs controlled by a microcontroller that transmits digitized signals in real time via a logging cable to the surface. A differential RS485 interface with intermediate optical coupling is used for signal transmission. Signal processing is performed in the software on the control laptop. The processing includes digital narrowband filtering using multipoint digital filters followed by phase-synchronous detection, which allows you to dramatically reduce the level of interference.