Inferred production rates of a rod pumped well from surface and pump card information
AssigneeLufkin Industries, Inc.
InventorsSam Gibbs, Kenneth Nolen
Life of this patent
Estimating the term…
Abstract
A method for inferring production of a rod pumped well. Inferred production is estimated in a well manager which not only performs pump-off control with a down-hole pump card, but also estimates liquid (oil-water) and gas production using the subsurface pump as a meter. Methods are incorporated in the well manager for identifying and quantifying several conditions: pump leakage, unanchored tubing, free gas and oil shrinkage. Quantifying such conditions in the well manger enables accurate inferring of production thereby eliminating the need for traditional well tests.
Claims13
A method for inferring production rate for a pumping cycle of a rod pumped well by using a subsurface pump (44) as a meter comprising the steps of, generating a down hole pump card from surface load and position measurements of a rod pumping unit (10),
- determining a position of traveling valve (TV) opening from said down hole pump card;
- determining from said down hole pump card a stroke distance Sn traveled by said plunger from said position of TV opening to a bottom of the stroke;
- determining the volume of free gas ΔVgas remaining in the pump at TV opening,
- determining a distance Sgas of the stroke distance Sn that corresponds to the volume of free gas ΔVgas remaining in the pump at TV opening;
- determining a distance Sl of the stroke distance that corresponds to the liquid stroke distance in the pump at TV opening from the equation, Sl=Sn−Sgas,
- determining net liquid production at pump pressure and temperature for said pumping cycle from the equation,
- Δ
-
-
- V
- 1
- =
- π
- 4
-
- d
- 2
-
- S
- l
- where ΔVl is net liquid production measured in cubic dimension at the pump,
- d is the diameter of the pump measured in length dimension, and
- Sl is measured at the pump in length dimension and
- converting ΔVl at pump conditions to stock tank conditions.
A method for inferring production rate for a pumping cycle of a rod pumped well by using the subsurface pump (44) as a meter comprising the steps of,
- generating a down hole pump card from surface load and position measurements of a rod pumping unit (10),
- determining the gross stroke Sg of the plunger of the subsurface pump (44) which pumps oil, water and gas to the surface via a production tube, where gross stroke Sg is the distance measured from the lowest position where the Traveling Valve TV closes to the highest position where the standing valve SV closes,
- identifying a characteristic of unanchored tubing by
- determining a distance St between TV closure to SV opening on said pump card, and
- determining a distance Sn as the distance traveled by the pump from TV opening to the bottom of the stroke from the equation
- Sn=Sg−St, and
- determining liquid production for said pumping cycle from the equation
- Δ
-
-
- V
- l
- =
- π
- 4
-
- d
- 2
-
- S
- n
- ,
- where
- ΔVl is measured in cubic dimension
- d is the diameter of the pump measured in length dimension, and
- Sn is measured in length dimension.
A method for inferring production rate for a pumping cycle of a rod pumped well by using the subsurface pump (44) as a meter comprising the steps of,
- generating a down hole pump card from surface load and position measurements of a rod pumping unit (10),
- determining the gross stroke Sg of the plunger of the subsurface pump (44) which pumps oil, water and gas to the surface via a production tube, where gross stroke SG is the distance measured from the position where the traveling valve TV closes to the position where the standing valve SV closes,
- determining fluid load from said pump card,
- determining tubing stretch from the equation
- S
- t
- =
- K
-
- L
- f
-
- D
- p
- E
- t
-
- A
- t
- where St is tubing stretch in length dimension
- K is a dimensional constant
- Lf is fluid load in lb
- Dp is the pump setting depth in length dimension
- Et is the modulus of elasticity of the tubing (Psi)
- At is the cross sectional area of the tubing (area dimension),
- determining a distance Sn as the distance traveled by the pump from TV opening to the bottom of the stroke from the equation,
- Sn=Sg−St, and
- determining liquid production for said pumping cycle from the equation
- Δ
-
-
- V
- l
- =
- π
- 4
-
- d
- 2
-
- S
- n
- ,
- where ΔVl is measured in cubic dimension
- d is the diameter of the pump measured in length dimension, and
- Sn is measured in length dimension.
A method for inferring production rate for a pumping cycle of a rod pumped well by using the subsurface pump (44) as a meter comprising the steps of,
- generating a down hole pump card surface load and position measurements of a rod pumping unit (10),
- determining the position of traveling valve (TV) opening of said pump from said down hole pump card,
- determining the distance Sl of the stroke distance of said pump that corresponds to the liquid stroke in the pump at TV opening,
- determining traveling valve (TV)/plunger leakage LTV rate for said pumping cycle,
- determining liquid production for said pumping cycle from the equation
- Δ
-
-
- V
- l
- =
- π
- 4
-
- d
- 2
-
- S
- l
- where ΔVl is measured in cubic dimension
- d is the diameter of the pump measured in length dimension,
- Sl is measured in length dimension;
- and
- determining net liquid production,
- ΔVnet=ΔVl−LTV(T)
- where T is the cycle time of said pumping cycle.
Dependencies are inferred from the claim text.