Method and apparatus for drilling a probabilistic approach

Patent metadata

Field	Value
Publication number	US-9863240-B2
Application number	US-57448909-A
Country	US
Kind code	B2
Filing date	Oct 6, 2009
Priority date	Mar 11, 2004
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

Methods and software tools for determining wellbore-strengthening information for a drilling operation, the method including inputting wellbore parameters into a wellbore simulator, importing wellbore-strengthening options into the wellbore simulator, and performing a plurality of wellbore simulations to obtain fracture information, wherein the performing the plurality of wellbore simulations includes selecting at least one of the wellbore parameters and determining the affect of the selected wellbore parameter on the wellbore. The method further includes selecting a wellbore-strengthening option based on the fracture information and outputting the selected wellbore-strengthening option.

First claim

What is claimed is:

1. A method comprising:
determining wellbore fracture information from a simulation that iteratively simulates wellbore parameters to determine an effect of the wellbore parameters on fractures in a wellbore wherein the wellbore parameters are selected from one or more of a group comprising: deviation, orientation, fracture length, wellbore radius, in-situ stress, bottom-hole pressure, and other rock elastic properties and further wherein the simulation selects one or more wellbore parameters to determine the effect of the wellbore parameters on the fractures by randomly sampling a selected wellbore parameter to quantify and transform the wellbore parameters into a statistical distribution and further wherein the simulation statistically samples the statistical distribution of the selected wellbore parameter and processes the samples deterministically to produce an approximate solution that is in the form of probabilistic values and/or ranges;
ranking the selected parameter against at least one other parameter of the group according to a user-defined importance;
determining an importance of the selected parameter relative to the at least one other parameter;
adjusting the selected parameter depending on the user-defined importance;
calculating a fracture width distribution based on the ranking and the effect of the wellbore parameters on the fractures in the wellbore wherein the fracture width distribution indicates a likelihood of encountering one or more fractures with a particular fracture width;
simulating a plurality of loss-prevention material options for each fracture width in the fracture width distribution, calculating, by application of an inversion technique, at least one gain in net fracture pressure as a result of at least one loss-prevention material options of the plurality of loss-prevention material options, and outputting an approximate solution including at least a distribution of fracture information;
selecting the optimum loss-prevention material option, from the simulated plurality of loss-prevention material options, for plugging at least one fracture having the particular fracture width; and
outputting the selected optimum loss-prevention material option; and
drilling a well using the selected optimum loss-prevention material option.

2. The method of claim 1 , further comprising:
obtaining a closed-form solution for the fracture width and performing fracture-aperture prediction performing an uncertainty analysis on the fracture information.

3. The method of claim 2 , further comprising: displaying the uncertainty analysis to a user.

4. The method of claim 1 , wherein the simulation is a Monte Carlo simulation.

5. The method of claim 1 , wherein the wellbore parameter comprises at least one of the group consisting of minimum horizontal stress, maximum horizontal stress, stress orientation, bottomhole pressure, Young's modulus, Poisson's ratio, wellbore diameter, and fracture length.

6. The method of claim 1 , further comprising:
inputting wellbore parameters into a wellbore simulator;
selecting a maximum wellbore parameter value;
selecting a minimum wellbore parameter value; and
selecting a most-likely wellbore parameter value.

7. The method of claim 1 , wherein the simulation further comprises:
performing a fracture-width calculation;
generating a fracture-width distribution; and
determining a probability for a fracture aperture.

8. The method of claim 1 , wherein the selected optimum loss-prevention material option comprises a loss-prevention material blend.

9. The method of claim 8 , wherein the loss-prevention material blend comprises at least one of sized synthetic graphite, calcium carbonate, and crushed nutshells.

10. The method of claim 8 , wherein the loss-prevention material blend comprises oversized and undersized particles.

11. A method comprising:
inputting a plurality of parameters into a simulator operatively associated with a processor;
ranking each parameter of the plurality of parameters according to a user-defined importance;
determining a relevance of each parameter relative to other parameters of the plurality of parameters;
adjusting each parameter according to the determined relevance of each parameter;
importing information related to loss-prevention materials into the simulator;
performing a plurality of iterative simulations to obtain facture information regarding one or more fractures in a wellbore wherein the plurality of iterative simulations comprise:
selecting at least one parameter from the plurality of parameters;
accessing a database comprising the information related to the loss-prevention materials;
determining an effect of the selected at least one parameter on the wellbore;
retrieving a representative sample from the plurality of parameters by randomly sampling the selected at least one parameter such that the selected at least one parameter is quantified by transforming the selected at least one parameter into a statistical distribution relating to a range and distribution of values and by statistically sampling the selected at least one parameter;
processing, deterministically, the representative sample;
producing an approximate solution by at least once repeating the retrieving and the processing; and
performing an uncertainty analysis comprising a fracture-width calculation to generate a fracture-width distribution, wherein a probability of risk of incurring a fracture of the one or more fractures in the wellbore with a particular width is determined based on the generated fracture-width distribution, wherein the probability of risk is displayable as a statistical output in one or more ranges of probabilistic values, wherein the plurality of iterative simulations generates an optimum strengthening solution for each of the one or more ranges of probabilistic values;

deriving wellbore fracture information comprising (a) the probability of risk of incurring a fracture of the one or more factures in the wellbore with a particular width in the one or more ranges of probabilistic values and (b) a gain in net fracture pressure, calculated by an inversion technique, as a result of a loss-prevention material or blend of loss-prevention materials; and
selecting an optimal loss-prevention material or blend of loss-prevention materials from the database based on the derived wellbore fracture information;
outputting the selected optimal loss-prevention material or blend of loss-prevention materials; and
drilling a well using the selected optimum loss-prevention material or blend of loss-prevention materials.

12. A non-transitory computer readable medium comprising a computer program, which when executed by a processor performs a method, the method comprising:
characterizing fractures in a wellbore based on wellbore parameters input by a user;
prioritizing the wellbore parameters by the computer program according, to an importance defined by the user, to assigned a rank to at least one wellbore parameter;
performing a simulation where the wellbore parameters are iteratively simulated by the assigned rank to determine an effect of one or more wellbore parameters on fractures in a wellbore and an effect of at least one wellbore parameter on the wellbore;
adjusting the wellbore parameter depending on the importance defined by the user;
generating fracture width information based on the ion, wherein the fracture width information includes a prediction of encountering a fracture with a particular width and further, wherein the simulation calculates at least one net fracture pressure by applying an inversion technique to calculate an approximate gain in net fractur

Assignees

• Geehan Thomas
• Guo Quanxin
• Zamora Mario
• M-I L L C

Inventors

• Geehan Thomas
• Guo Quanxin
• Zamora Mario

Classifications

• E21B49/006 Primary

  Measuring wall stresses in the borehole · CPC title

• C09K8/62

  Compositions for forming crevices or fractures · CPC title

• G01V2210/66

  Subsurface modeling · CPC title

• E21B43/267

  reinforcing fractures by propping · CPC title

• E21B21/003

  Means for stopping loss of drilling fluid (plastering the borehole wall E21B33/138) · CPC title