Apparatus for analysis and control of a reciprocating pump system by determination of a pump card
View Patent ↗An instrumentation system for assessing operation of a reciprocating pump system which produces hydrocarbons from a non-vertical or a vertical wellbore. The instrumentation system periodically produces a downhole pump card as a function of a directly or indirectly measured surface card and a friction law function from a wave equation which describes the linear vibrations in a long slender rod. A control signal or command signal is generated based on characteristics of the downhole pump card for controlling the pumping system. It also generates a pump and well analysis report that is useful for a pump operation and determination of its condition.
1. An instrumentation system for assessing operation of a reciprocating pump system producing hydrocarbons from a non-vertical wellbore which extends from the surface into the earth, the system comprising,
a data gathering system which provides signals representative of surface operating characteristics of the pumping system, and characteristics of said non-vertical wellbore,
a processor which receives said operating characteristics with said characteristics of said non-vertical wellbore and generates a surface card representative of surface polished rod load, as a function of surface polished rod position, with
said processor determining a friction law function based on said characteristics of said non-vertical wellbore, and with
said processor periodically generating a downhole pump card as a function of said surface card and said friction law function for a wave equation which describes the linear vibrations in a long slender rod, wherein the friction law function for the wave equation is represented as follows:
C
(
x
)
=
δμ
(
x
)
[
Q
(
x
)
+
T
(
x
)
∂
u
(
x
,
t
)
∂
x
]
,
wherein
δ
=
∂
u
(
x
,
t
)
/
∂
t
∂
u
(
x
,
t
)
/
∂
t
t=time in seconds;
x=distance of a point on the unrestrained rod measured from the polished rod in feet,
and where
u(x), Q(x) and T(x) are determined by mathematical modeling of a rod string in said wellbore.
2. The system of claim 1 wherein,
said processor includes pump card analysis software which produces a control signal for controlling said pump.
3. The system of claim 1 wherein,
said pump card analysis software produces a control signal to turn off a drive motor of said pump if a pump card indicator is recognized requiring pump shut off.
4. The system of claim 1 wherein,
said pump card analysis software produces a control signal to control a variable speed of the pump if a pump card indicator is recognized which indicates that varying the speed of the pump enhances pump operation.