Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
  • G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
  • G01V1/28—Processing seismic data, e.g. for interpretation or for event detection
  • G01V1/30—Analysis

Definitions

• the present invention relates to the binning of oil and gas exploration and production scientific data for an area of interest and relates to the generation of oil and gas exploration and production data attributes.
• the goal of hydrocarbon exploration is to find porous and permeable geologic deposits containing high pore-space saturations of hydrocarbons, under sufficient pressure to allow some mode of commercial production, hi pursuit of this goal, companies, countries and individuals collect and process many types of geophysical and geological data.
• the data is often analyzed to find anomalous zones that can reasonably be attributed to the presence of hydrocarbons.
• 2D and 3D seismic data anomalies has been a standard practice in the petroleum industry since the 1960s.
• Other geologic and geophysical data anomalies have been tried, sometimes successfully, for over a century. These include various gravimetric, electromagnetic, chemical, biological and speculative methods.
• a third problem is that a basic physical property at work in hydrocarbon reservoirs is that both oil and gas are less dense than water. This generally causes oil and gas to accumulate up- structure in the pore-space of potential reservoir rocks. The higher water saturations are found, generally, down-structure. This separation of saturations is driven by gravity. When such a separation of fluid types occurs, flat interfaces, in depth, are expected to form.
• the hydrocarbon reservoir will have one response for each hydrocarbon type.
• the water-saturated part of the reservoir may have a second data response and the interfacial area a third type of attribute data response.
• This sequence of responses in the processed attribute data allows for a simultaneous analysis of the three classes.
• neither the water saturated reservoir response nor the single component hydrocarbon saturated reservoir response are expected to vary with structural position.
• the transition from one type of fluid saturation to another, having a different density is expected to occur at a single depth or seismic travel time within the attribute data set. This change from saturation state to another at a given depth and location should be detectable using a quantitative tool.
• Another problem is that the strength of many types of data attribute anomalies is dependent on the rock physics of the geologic systems. Some anomalies are very evident in the data. Others can be very subtle and cause considerable debate. Another associated problem is that much work in hydrocarbon exploration continues to be done in areas where the data are poor, noisy or difficult to interpret. In areas of good data quality, many high-strength anomalies are adequately interpreted by inspection. As the data quality and/or imagining ability of the data degrade, it can be very difficult to verify that a legitimate anomaly does or does not exist in a given set of data, especially when the rock physics suggests that any meaningful anomaly would be subtle.
• This current invention also can be used for the quantification of changes in lithology, facies, or rock fabric from one location to another. It is designed to function in areas of low signal-to-noise and aid in the determination of data suitability for hydrocarbon detection for the expected rock physics environment. This allows the invention to be applied to the detection of subtle hydrocarbon related data anomalies.
• This invention also is designed to quantify responses and quantify response uncertainties in a manner that can be consistently defined, reported and replicated by others. Quantification and replication make the output of this invention suitable for quantitative comparison with rock physics analyses, petro-physical analyses, response modeling and geologic analyses (e.g., fit to structure analysis). This combination of capabilities represents an advance over current methods.
• the method of the present invention provides a method for horizon binning for an area of interest by merging an attribute file with a second horizon file.
• the method also entails identifying an area of interest of the merged file and identifying a time range for a time horizon file, or a depth range for a depth horizon file, over which to perform the analysis.
• the next step is proposing a theory that the identified area has a portion contiguous between a hydrocarbon and water-bearing area.
• the method continues by binning the attribute data within the identified area of interest using a file with time or depth values and computing a calculated value for each time or depth bin.
• the method entails creating a plot of the computed value versus the first value for each bin and viewing the plot to ascertain if a discontinuity corresponding to a fluid contact is evident.
• the method ends by using a magnitude shift in the attribute statistic of the water and hydrocarbon reservoir models to confirm the theory and using the magnitude shift to determine a boundary between the water and hydrocarbon reservoir model and the corresponding water and hydrocarbon reservoirs for an identified area.
• the method for deriving a GrAZ seismic attribute file entails inputting horizon file data and then obtaining the gradient of the horizon file, thereby producing a horizon vector file.
• the method next involves inputting attribute file data, indexing from the attribute file data at corresponding geographic locations of the horizon file, forming an attribute file, and obtaining the gradient of the attribute file thereby producing an attribute vector file.
• the method ends by performing a compilation of the horizon vector file and the attribute vector to ascertain if changes are in a direction towards a surface datum for a narrow time and depth range are detected and measured.
• the present method was conceived to detect the changes in attribute response when moving from a water reservoir to a hydrocarbon reservoir in order to determine if exploration or production activities should continue in a given area.
• the method was conceived to operate in high noise, low signal to noise environments, where the data quality is poor.
• the method was designed to operate on subtle hydrocarbon indicators. It was designed to fully characterize the water reservoir inner and outer edges and the hydrocarbon inner and outer edges as well as the interface between these reservoirs.
• the method was also conceived to determine the errors and uncertainties in all measurements and data attribute results relative to a given hydrocarbon reservoir and the corresponding water reservoir.
• the preferred embodiment is a method for horizon binning for an area of interest.
• An area of interest means within the context of this patent application, a closed polygon, such as a shape with at least 3 sides, like a triangle, and more preferably a shape having up to N sides, for a positive integer N > 2.
• the closed polygon may have more sides if the area of interest includes a group or a set of closed polygons or if more sides are needed to describe the region of under study.
• the area of interest also can be the interior of the closed polygon or the union of the interiors of the set of closed polygons.
• Each closed polygon can be defined using geographic coordinates such as latitude-longitude, x-y prospect coordinate system, the x-y field development coordinate system and the internal 3-D seismic survey coordinates, such as line and trace numbers from a specific survey.
• an area of interest can be either a geographic area for a hydrocarbon reservoir, an associated water reservoir, contiguous combinations of these or combinations of these with other reservoirs.
• an attribute file with attribute values is merged with a second file.
• An attribute file is defined as either a set of compiled seismic reflection data, such as 3-D data sets in an area considered to be for oil and gas production, which is then processed using a defined attribute generating algorithm, such as instantaneous amplitude, ANO slope, or RMS amplitude over a window.
• a particularly useful defined attribute is the background normalized root means squared (RMS) amplitude.
• attribute data associated with a horizon of interest is extracted using the processed data.
• a horizon of interest is a geologic or geophysical surface in the earth that is considered a good prospect for oil and gas production.
• the horizon of interest can be defined by a time file that is a set of two way seismic time values depicting the seismic travel time from the datum to the horizon of interest and back to the datum.
• the datum is the reference elevation from which travel times in a seismic dataset time file or interpretation is measured.
• the datum is the reference elevation from which depths for a horizon of interest are measured.
• the horizon of interest can be defined by a depth file that is a set of values that depict the depth from the datum to the horizon of interest, with increasing depth values toward the center of gravity of the Earth.
• Another attribute file can be a set of compiled seismic velocity data processed using a defined attribute generating algorithm and extracted for or in conjunction with a horizon of interest.
• Still another attribute file usable in the method can be a set of geophysical gravity data extract, compiled or collected for a horizon of interest.
• Another usable attribute file can be a set of geophysical remote sensing data extracted for a horizon of interest, or a set of compiled or collected geologic measurements for a horizon of interest, such as fluid saturation within a reservoir formation.
• Two other attribute files that usable within this method would be a set of petro-physical measurements, such as resistively, for a horizon of interest, and a set of compiled or collected engineering data, such as initial production rate (IP) for a horizon of interest.
• IP initial production rate
• the attribute file can be a set of compiled seismic reflection data, processed using a defined attribute generating algorithm and extracted for, in relation to or in conjunction with a horizon of interest or a set of compiled seismic velocity data processed using a defined attribute generating algorithm and extracted for or in conjunction with a horizon of interest.
• the attribute file can also be a set of geophysical gravity data extracted, compiled, or collected for a horizon of interest or a set of geophysical remote sensing data extracted or compiled for a horizon of interest.
• the attribute file can also be a set of petro-physical measurements for a horizon of interest, a set of compiled or collected engineering data for a horizon of interest, or any combination thereof.
• the second file can be a time file with time values, such as the seismic travel time from and to a horizon of interest in a 3-D seismic data set.
• the second file can be a depth file with depth values, such as the depth from sea level to specific geologic formation within the Earth.
• a merged file is formed.
• the merging of the two files is performed using geographic coordinates such as longitude-latitude, the x-y prospect coordinate system for an area undergoing hydrocarbon prospecting or development, the x-y prospect field development coordinate system of a field undergoing hydrocarbon prospecting or development, or 3-D seismic survey coordinates, such as line and trace numbers from a specific survey.
• an identified area of interest is formed from the merged file, hi a preferred embodiment, the area of interest is the geographic intersection of the area of interest and the merged file.
• the geographic intersection is created by constructing file sets taken from the merged file whose members include, a geographic location G, an attribute at geographic location G, a horizon time or depth value at geographic location G where all such geographic locations G are within the area of interest.
• a theory is proposed that has the identified area having at least a portion that is contiguous between a hydrocarbon reservoir and a water reservoir forming an interface.
• the interface of the hydrocarbon reservoir with the water reservoir is proposed as the furthest extent of high hydrocarbon saturation in the down structure direction.
• the interface is a point of contact between dissimilar fluids within the pore space.
• a hydrocarbon reservoir can have a plurality of interfaces of hydrocarbon types, such as oil and gas, with a plurality of water reservoirs. It is contemplated that the hydrocarbon interface can be a plurality of layered hydrocarbon types.
• the theory also can include the hypothesis that the interface is located at a single depth, or at a depth corresponding to a single two way seismic travel time.
• a calculated value for each bin is formed using any of the following: a. an average of attribute values within the bin; b. an average absolute value of the attribute values within the bin; c. a standard deviation for attribute values within the bin; d. a maximum of attribute values within the bin; e. a minimum of attribute values within the bin; f. a range of attribute values within the bin; g. a range of attribute absolute values within the bin; h. a median for attribute values within the bin; i. a mode for attribute values within the bin; j . a skewness for attribute values within the bin; k. a plurality of defined moments for attribute values within the bin; and 1. combinations of these values noted above and the corresponding uncertainty of each for each bin.
• a diagram or plot is created of the above values by plotting the computed value relative to the first value, second value, or mid-point value for each formed bin.
• the plot is then viewed to determine if a discontinuity or interface between a hydrocarbon reservoir and a water reservoir exists that depicts a fluid contact.
• This method is particularly useful in areas where the signal to noise ratio in the data is particularly low, in situations where there is more noise than signal in the data.
• FIG 1 depicts the overall flow of the method.
• the horizon and data attributes are chosen (Step 110).
• the horizon is input to the program as a time file or as a depth file that is geographically indexed (Step 120) and the data attribute is extracted and input to the program as a geographically indexed file (Step 130).
• the horizon file is merged with the attribute file using geographic coordinates (Step 140). This step forms a file termed a merged file.
• the next step, shown in FIG 1, is that a closed polygon and/or a set of closed polygons are geographically defined as the area of interest (Step 160). Portions of the merged files not within the set of closed polygons are deleted (Step 180) thereby generating an identified area.
• Step 240 (i) a range of data in time or depth of the identified area and (ii) the sequence of bins for the identified area are specified.
• the attribute data of the identified area are binned forming a set of binned data (Step 260). Each bin is identified by the time or depth range of the values of the identified area within the bin. The statistics to be computed for each bin of the binned data are chosen (Step 280).
• the statistics and the uncertainties for each statistic are then computed for each bin of the binned data (Step 300).
• the results of external studies, modeling the geological attribute response, geophysical attribute response or engineering attribute response of the theorized system are input to the process (Step 330).
• the theorized and modeled system should address the geologic, rock physics, pore saturation, data acquisition, data processing and data presentation elements of the process as it applies to the identified area at the horizon of interest.
• the statistics and uncertainties for all bins are examined to determine if they and any input model results are consistent with the theory of the existence of at least one interface separating regions of different pore fluid saturation for fluids of differing densities (Step 340).
• This examination step also determines if the up-stracture bin statistics and uncertainties are consistent with at least one hydrocarbon response and whether the down-structure bin statistics and uncertainties are consistent with a high water saturation response or a heavier hydrocarbon response.
• the range of times or depths (for an input time file or input depth file, respectively) of the at least one interface is estimated and corresponding uncertainties are computed (Step 360).
• Step 380 the final output results are written, plotted in map form, and/or displayed in a 3D visualization format using an electronic display device
• Step 390 the final output results are written, plotted in map form and/or displayed in a 3D visualization format in a document format
• FIG 2 shows the geometry of a hydrocarbon reservoir 404, a water reservoir 405 and the interface 406 between the hydrocarbon reservoir and the water reservoir. It is also possible that 405 can be a heavier hydrocarbon reservoir as compared with hydrocarbon reservoir 404.
• the datum surface 400 is the datum from that all depths and times are measured.
• Element 401 indicates the direction of increasing depth and/or increasing seismic travel time as measured from the datum surface 400.
• the surface 402 gives the bounds of the hydrocarbon water reservoirs.
• the bottom 403 gives the lower bounds of the hydrocarbon/water reservoirs.
• Either the top surface 402 or the bottom surface 403 may serve as a typical horizon of interest.
• the horizon of interest may be any surface defined to be as surface expressible as a one-to-one function of either (or both) the top surface 402 or the bottom surface 403.
• the geologic region of proposed high water saturation and minimal or no productive hydrocarbon saturation 405 is also shown in FIG 2.
• the interface 406 divides the two geological regions, 404 and 405.
• the interface 406 is normally expected to be flat with respect to the depth or time axis 401.
• the layer 502 is another hydrocarbon reservoir containing a high hydrocarbon saturation of a type that is less dense than the saturating fluid(s) in the layer 501.
• the top layer 503 is a hydrocarbon reservoir containing a high hydrocarbon saturation of a type that is less dense than the saturating fluid(s) in the layer 502. It is to be understood that FIG 3 illustrates only one embodiment, and various reservoirs can form specific layers of the form shown as 503, 502, 501, and 504.
• FIG 4 depicts the interface between a plurality of hydrocarbon saturation types along the water reservoir, separated by permeability barriers or other barriers to fluid exchange.
• impermeable layers are shown as elements 624, 634, 644, and 654. These impermeable layers can be faults, gouge materials, facies changes or similar geologic elements. Again, FIG 4 is only one embodiment. Various other elements can form each specific layer, 604, 610, 620, 630, 640, and 650.
• the water reservoir is a geologic rock formation having both porosity and permeability and saturated primarily by water.
• the water formation may contain a partial hydrocarbon saturation, but at a sufficiently low level so as to preclude economic development.
• the hydrocarbon reservoir is a geologic rock formation having both porosity and permeability and saturated in most cases by a combination of water and hydrocarbons.
• the saturation of hydrocarbons must be sufficiently high so as to allow economic development. If the saturation of hydrocarbons does not allow the production of hydrocarbons and associated water in quantities that are commercial, the reservoir would not be called a hydrocarbon reservoir.
• the hydrocarbon reservoir is found up-structure of the water reservoir, which is located down- structure.
• up-structure refers to shallower depths from the surface within the earth.
• Down-structure refers to deeper depths within the earth. In the case of seismic travel times, deeper depths correspond to larger absolute value seismic travel times and shallower depths to smaller absolute value travel times.
• Both depths and seismic travel times are typically measured from a specified datum.
• the datum is a specified surface to which measurements are referenced.
• the term deeper means increasing depth values from the datum toward the center of gravity of the Earth. Seismic two way travel times will typically increase for reflections from geologic units in the general direction of the center of gravity of the Earth from the datum.
• the datum is typically taken to be mean sea level. Depths or seismic times are then referenced to mean sea level as the datum and increase, indicating deeper, in a direction toward the center of gravity of the Earth, hi this discussion, the difference between the center of gravity of the Earth and the centroid center of the Earth is considered negligible.
• an embodiment is a method for deriving a seismic attribute file.
• the method addresses the case of multiple hydrocarbon zones, such as, gas over oil over water. It is designed to specifically test a model wherein gas is less dense than oil and oil is less dense than water, and data responses vary by structural position, but transition in a narrow range of depths or two-way seismic times. In a preferred embodiment, the narrow range would not exceed 5% of the total seismic two-way time or depth range contained within the horizon file.
• this method is designed to verify that the data attribute response is invariant with respect to structural position.
• the quantification of this invariance and the associated uncertainty allow baselines to be established with respect to which the significance of an interfacial signal can be assessed.
• the preferred embodiment also relates to amethod for deriving a GrAZ seismic attribute file.
• the method begins by inputting a horizon file and inputting an attribute file.
• the attribute file and the horizon file must contain data elements at corresponding geographic coordinates.
• the geographic coordinates can be an X-Y prospect coordinate system, X- Y field development system, latitude and longitude, internal 3D seismic survey coordinates, and combinations thereof.
• the data must be sufficiently continuous to allow the computation of a first derivative in each coordinate direction in each file, neglecting geographic edge effects.
• the next step involves obtaining the gradient of the horizon file thereby producing a horizon vector file, having components, dHl and dH2 at each location G.
• the first component, dHl is the partial derivative of the horizon depth or seismic two-way time in the first coordinate direction at G.
• the second component, dH2 is the partial derivative of the horizon depth or seismic two-way time in the second coordinate direction at G.
• the next step involves obtaining the gradient of the attribute file thereby producing an attribute vector file, having components, dAtl and dAt2 at each location G.
• the first component, dAtl is the partial derivative of the attribute value in the first coordinate direction at G.
• the second component, dAt2 is the partial derivative of the attribute value in the second coordinate direction at G.
• the final step of the method involves performing a compilation of the horizon vector file and the attribute vector file to form a combined attribute file, GrAZ.
• the combined attribute file is studied to ascertain if observed changes in the attribute file are in a direction towards a surface datum for a narrow range of time and depth. If any components of either the horizon vector file or the attribute vector file do not exist or can not be computed at a location G, then no member of the combined attribute file, GrAZ exists at G or is assigned to the location G.
• the method can further include the step of using dot product mathematics to perform the compilation.
• the dot product mathematics is a summation at each geographic location G of the product of corresponding elements of the horizon vector file and the attribute vector file at each geographic location G.
• the dot product is the sum of dHl multiplied by dAtl with dH2 multiplied by dAt2. If any of the quantities dHl, dH2, dAtl or dAt2 do not exist or cannot be computed as finite real numbers at a location G, then a dot product is not performed and no element of the combined attribute file, GrAZ, exists at G or is assigned to the location G
• the horizon file is a time horizon file made of a set of two-way seismic time values depicting the seismic travel time from the datum to the horizon of interest and back to a datum.
• the horizon file can be a depth horizon file made of a set of values that depict the depth from a datum to the horizon of interest within the Earth.
• the attribute file in the method can one member of the following: a. a set of compiled seismic reflection data processed using a defined attribute generating algorithm, and extracted for a horizon of interest; b. a set of compiled seismic reflection data processed using a defined attribute generating algorithm in conjunction with a horizon of interest; c. a set of compiled seismic velocity data processed using a defined attribute generating algorithm and extracted for a horizon of interest; d. a set of compiled seismic velocity data processed using a defined attribute generating algorithm in conjunction with a horizon of interest; e. a set of geophysical gravity data extracted for a horizon of interest; f. a set of geophysical gravity data compiled for a horizon of interest; g.

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• 2004
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