Method and apparatus for communicating with devices downhole in a well especially adapted for use as a bottom hole mud flow sensor

In a drill string having a drill bit and through which a drilling mud is pumped by at least one pump having at least one piston stroked at a stroke rate within a predetermined range, a method of determining whether said pump is pumping said mud, comprising the steps of:

• a) sensing pressure pulsations in said drilling mud proximate said drill bit;
• b) determining whether the amplitude of the portion of said pressure pulsations that is within a predetermined frequency range exceeds a predetermined value;
• and
• c) determining that said pump is pumping said mud based on said comparison in step (b).

A method of communicating steering command information to a steerable bottom hole assembly disposed in a well bore from a location on the earth's surface, said bottom hole assembly being surrounded by a fluid and being a portion of a drill string, the method comprising the steps of:

• a) directing pressure pulsations down said fluid to said bottom hole assembly from said surface location, said pressure pulsations having a characteristic indicative of said steering command information to be communicated;
• b) sensing said pressure pulsations received at said bottom hole assembly;
• and
• c) analyzing said characteristic of said pressure pulsations in said bottom hole assembly so as to decipher said steering command information being communicated.

A method of regulating the flow of fluid from a producing well by controlling a valve located down hole in said well from a location on the earth's surface, the method comprising the steps of:

• a) locating a pressure pulsation sensor assembly in said well proximate said valve;
• b) directing pressure pulsations down said fluid to said sensor assembly from said surface location, said pressure pulsations having a characteristic indicative of an instruction to be communicated for controlling said valve;
• c) sensing said characteristic of said pressure pulsations received by said sensor assembly;
• d) analyzing said characteristic of said sensed pressure pulsations so as to decipher said instruction, said analysis being conducted down hole in said well;
• e) sending a signal from said sensor assembly to said valve instructing said valve to operate in accordance with said instruction deciphered by said sensor assembly;
• and
• f) operating said valve in accordance with said instruction so as to regulate the flow of said fluid produced by said well.

An apparatus for controlling the flow of fluid from a multilateral well having at least first and second branches, comprising:

• a) first and second fluid flow control devices for controlling the flow of fluid downhole in said first and second branches of said multilateral well, respectively, in response to a signal received;
• b) means for generating pressure pulsations in said fluid proximate the surface of the earth for transmission downhole to said first and second branches of said multilateral well, said pressure pulsations having a characteristic indicative of an instruction for operating at least one of said first and second fluid flow control devices;
• c) at least one sensor assembly for sensing said pressure pulsations at a location downhole in said well;
• and
• d) a microprocessor for analyzing said characteristic of said pressure pulsations sensed so as to decipher said instruction and for sending a signal to at least one of said first and second fluid flow control devices instructing said device to operate in accordance with said instruction.

In a multilateral well having at least first and second branches into which first and second flow control devices, respectively, are installed, each of said first and second flow control devices being operative in response to a signal received, a method for individually controlling the flow of fluid from at least said first and second branches, comprising the steps of:

• a) generating pressure pulsations in said fluid proximate the surface of the earth for transmission downhole to at least a selected one of said first and second branches of said multilateral well whose fluid flow is to be controlled, said pressure pulsations having a characteristic indicative of an instruction for operating the one of said first and second fluid flow control devices installed in said selected branch;
• b) sensing said pressure pulsations at a location downhole in said well;
• d) analyzing said characteristic of said pressure pulsations sensed so as to decipher said instruction;
• e) sending a signal to at least said one of said fluid flow control devices installed in said selected branch instructing said device to operate in accordance with said instruction;
• f) operating at least said one of said fluid flow control devices to which said signal was sent so as to control the flow of fluid from said selected branch.