Method of determining inflow rates from underbalanced wells
First Claim
1. A method of determining the flowrate of fluid into the wellbore of a well, the well having a tubing string extending downwardly from a wellhead into a casing string which penetrates a fluid-bearing formation, said strings forming an annulus between them, said tubing string having a bore and a means for perforating the casing being located at the tubing string'"'"'s lower end, the casing initially acting to block communication of the fluid with the wellbore, comprising:
- removing sufficient liquid from the well so that it is in an underbalanced state and has a gas-filled space being formed above any liquid remaining therein;
establishing the volume of the gas-filled space;
blocking all means of fluid egress from the tubing bore and annulus at the wellhead;
perforating the casing at the fluid-bearing formation;
measuring the change in pressure in the tubing bore and annulus at the wellhead over time to determine its rate of change; and
establishing the rate of fluid inflow to the tubing bore and annulus as a function of the volume of the gas-filled space and said pressure change rate.
2 Assignments
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Accused Products
Abstract
A method is provided for determining the inflow rates of gas and liquid upon completion of an underbalanced well. The casing is placed, blocking fluid communication between the well and the formation. A tubing string is run in, forming an annular space and a tubing bore. The well is conditioned by removing sufficient liquids to create an underbalanced state and leaving a gas-filled space above any residual liquid. The volume of the gas-filled space in the annular space and the tubing bore is determined. The well is perforated, opening communication between the well and the formation. Pressure within the tubing bore and annulus is measured as a function of time. The rate of change of pressure is dependent upon the nature of the incoming fluid; be it gas or liquid. From the above, the rate of incoming fluid can be established as a function of the volume of the gas-filled space and the rate of change of pressure. The inflow rates of solely gas or solely liquid may be determined whether substantially all the liquid is removed during conditioning or only some of the liquid is removed.
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Citations
5 Claims
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1. A method of determining the flowrate of fluid into the wellbore of a well, the well having a tubing string extending downwardly from a wellhead into a casing string which penetrates a fluid-bearing formation, said strings forming an annulus between them, said tubing string having a bore and a means for perforating the casing being located at the tubing string'"'"'s lower end, the casing initially acting to block communication of the fluid with the wellbore, comprising:
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removing sufficient liquid from the well so that it is in an underbalanced state and has a gas-filled space being formed above any liquid remaining therein; establishing the volume of the gas-filled space; blocking all means of fluid egress from the tubing bore and annulus at the wellhead; perforating the casing at the fluid-bearing formation; measuring the change in pressure in the tubing bore and annulus at the wellhead over time to determine its rate of change; and establishing the rate of fluid inflow to the tubing bore and annulus as a function of the volume of the gas-filled space and said pressure change rate. - View Dependent Claims (2, 3, 4, 5)
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Specification