RU2810359C1 - Method for developing multi-layer oil deposit with horizontal well - Google Patents

Abstract

FIELD: oil production.

SUBSTANCE: used for the development of multi-layer oil deposits with horizontal wells, especially in cases where the geological section of the development object is composed of alternating layers with a significant difference in filtration and capacitance characteristics. A method for developing a multi-layer oil deposit with a horizontal well includes designing the trajectory of a horizontal wellbore of a production well and drilling a horizontal wellbore of a production well, characterized in that preliminarily, based on the results of exploratory drilling or data from a geological model of the drilling site for a horizontal production well, a multi-layer development object is identified and economically viable recoverable oil reserves are determined for one designed horizontal production well. Next, a production well with a horizontal shaft length is designed and the coefficients of open porosity, oil saturation and vertical thickness of oil-saturated layers in each layer of a multi-layer development object are determined. Then, for each formation, the weighted average porosity coefficient and the weighted average oil saturation coefficient are determined. Then the effective radius of the formation is determined separately for each layer. Next, the effective fraction of each layer is determined. Next, the effective penetration length of each layer is determined. After that, a horizontal well is drilled, taking into account the effective penetration lengths of each layer, and its operation is carried out.

EFFECT: increased efficiency of the method for developing a multi-layer oil deposit using a horizontal well.

1 cl, 1 tbl

Description

The invention relates to the field of oil production and can be used for the development of multi-layer oil deposits with horizontal wells, especially in cases where the geological section of the development object is composed of alternating layers with a significant difference in filtration and capacitance characteristics.

There is a known method for drilling horizontal wells with a remote bottom (patent RU No. 2278939, IPC E21B 7/04, published June 27, 2006), including initial curvature with a set of zenith angle to a value not exceeding a critical value corresponding to a violation of the stability of the well walls and stabilization areas zenith angle and increasing it to 90°, drilling a horizontal shaft and entering the design corridor of the productive formation after increasing the zenith angle to more than 90°, followed by drilling the production section. The vertical section from the wellhead, sections of initial curvature and stabilization of the zenith angle is carried out to the point of opening the roof of the productive formation of the anticline along a trajectory corresponding to the minimum possible length of the trunk. The minimum permissible distance from the point of opening the roof of the formation to the level of the GWC or OWC must satisfy the condition calculated using a mathematical expression. The placement of sections of curvature with an increase in the zenith angle to 90° and a rising subhorizontal section is carried out in the bottom rising part of the anticline formation. When the production section is located on the downward part of the anticline opposite from the wellhead, the rising subhorizontal section is driven to a point remote from the entrance of the production section at a distance determined by a mathematical expression. The method is aimed at increasing the reliability of drilling a horizontal well with a remote bottom to the anticline of a productive formation, located outside the drilling rig in the thickness of unstable rocks prone to collapse and trenching.

There is a known method for developing an oil deposit with horizontal wells (patent RU No. 2605860, IPC E21B 43/16, published on December 27, 2016 in Bulletin No. 36), including drilling horizontal wells. Horizontal shafts are placed at an angle of 0-30° to each other in a horizontal plane at a distance of 50-500 m. Production and injection wells alternate. Based on drilling data, a map of the distribution of reservoir permeability in the drainage area of horizontal wells is constructed. The maps identify zones that differ from each other by more than 1.5 times in permeability. Where horizontal shafts cross the transition from one zone to another, packers are installed. This breaks the horizontal trunks into sections. The length of each section is set to be at least 10 m. Development begins by lowering pumps into horizontal shafts of production and injection wells in the most permeable areas. After the reservoir has been developed opposite one of the sections in one of the production wells, the pump of this well is moved and installed in a horizontal well in the section next to the decrease in permeability. When moving all the pumps of production wells to the next section in terms of permeability, the pump in the injection wells is also moved to the next section, also by decreasing permeability. In each well, when one of the sections in the horizontal well is operating, the remaining sections of the same horizontal well are disconnected using the above-mentioned packers. The procedure for moving pumps to less permeable areas is repeated, carrying out sequential production of the entire deposit from greater to less permeable.

The closest to the invention in technical essence is a method for opening a productive inclined formation with a pressure regime for hydrocarbon production (patent RU No. 2165514, IPC E21B 7/06, published on April 20, 2001 in Bulletin No. 11), including drilling out the productive formation from the roof to the bottoms of single- or multilateral horizontal wells, characterized in that during the drilling process the zenith angle of the wellbore on the roof of the productive formation is increased to 90 ^o , the horizontal sections of the trunks of single-hole and multilateral wells are drilled with an inclination angle of 0 ^o , and when visually analyzing the structural map of the deposit in In the case of a single-hole well, a horizontal section is drilled in the direction perpendicular to the external or internal contours of the gas-oil or water-oil contacts (GOC or OWC), and its length is determined by the formula

where S ₁ is the length of the horizontal section of a single-hole well in the productive formation, m;

h is the true thickness of the productive formation, m;

_αpl - angle of inclination of the productive formation, degrees,

in the case of a multilateral well, horizontal sections of the wellbore are drilled at an angle formed in the formation plan by the axis of each horizontal section with the external or internal contours of the GOC or OWC, and determined from the expression

where β _m is the angle formed in the formation plan by the axis of each horizontal section of the wellbore with the external or internal contours of the GOC or OWC, degrees;

C is the distance between the external and internal contours of the GNK or VNK, m;

σ - half the distance between production wells in a row, m,

and their length is determined by the formula

where S ₂ is the length of each horizontal section of the multilateral well, m.

The disadvantage of all methods is the non-optimal opening of layers in a complex multi-layer development object with a horizontal wellbore, because the vertical variability of the filtration and reservoir characteristics of the reservoir section is not taken into account, which creates high risks of uneven production of moving reserves in the drainage zone of a horizontal wellbore and rapid breakthrough of underlying or injected water through individual layers of a multilayer reservoir with subsequent watering of the resulting product.

The technical result is to increase the efficiency of the method for developing a multi-layer oil deposit with a horizontal well by increasing the accuracy of the optimal placement of a horizontal well by creating a refined project for the development of a multi-layer object, which takes into account the main parameters of the filtration and reservoir properties of each layer, and evaluates the probable potential of mobile oil reserves in the drainage zone of the share horizontal production wellbore in each formation, the design length of the horizontal production wellbore is divided into zones with the distribution of oil reserves in each formation.

The technical result is achieved by a method for developing a multi-layer oil deposit with a horizontal well, including designing the trajectory of a horizontal production well bore, drilling a horizontal production well bore.

What is new is that, based on the results of exploratory drilling or data from a geological model of the drilling site for a horizontal production well, a multi-layer development object is identified, economically viable recoverable oil reserves are determined for one designed horizontal production well, a production well is designed with a horizontal trunk length, and then the coefficients are determined open porosity Kp, oil saturation Kn and vertical thickness hi of oil-saturated layers in each layer of a multi-layer development object, then for each layer the weighted average porosity coefficient Kp.av.v is determined. and weighted average oil saturation coefficient Kn.av.v. according to the formulas:

Kp.av.vz. = ((hi1 * Kп1) + (hi2 * Kп2) +…+ (hin * Kпn)) / (hi1+ hi2+…+ hin), fractions of units, where hi1 is the vertical thickness of the first oil-saturated layer from the roof of the layer,

hi2 – vertical thickness of the second oil-saturated layer from the roof of the layer,

hin is the vertical thickness of the last oil-saturated layer from the top of the layer,

Kp1…Kpn is the coefficient of open porosity in a given layer,

and Kn.sr.vz. = ((hi1 * Kн1) + (hi2 * Kн2) +…+ (hin * Kнn)) / (hi1+ hi2+…+ hin), fractions of units, where hi1 is the vertical thickness of the first oil-saturated layer from the roof of the layer,

hi2 – vertical thickness of the second oil-saturated layer from the roof of the layer,

hin is the vertical thickness of the last oil-saturated layer from the top of the layer,

Kn1…Knn – oil saturation coefficient in a given layer,

Next, the effective radius of the formation is determined separately for each layer using the formula:

Ref. = ( Kp.av.v. * Kn.av.v. * (hi1+ hi2+…+ hin)), m,

Next, the effective share of each layer is determined using the formula:

Cef. = (Ref. / (Ref1+ Ref2+ ... + Refn)), fraction of units,

where Ref1…Refn is the effective radius in each layer, then the effective opening length of each layer is determined by the formula:

Lef. = Cef. * Lгс, m, where Lгс is the length of the horizontal wellbore of the production well, providing economically viable recoverable oil reserves, after which a horizontal well is drilled, taking into account the effective penetration lengths of each formation, and its operation is carried out.

The method is carried out as follows.

Based on the results of exploratory drilling or data from a geological model of a horizontal well drilling site, a multilayer development object is first identified.

Determine economically viable recoverable oil reserves per project horizontal production well.

A production well with a horizontal trunk length is designed to provide economically viable recoverable oil reserves.

Next, the coefficients of open porosity Kp, oil saturation Kn and vertical thickness hi of oil-saturated layers in each layer of a multi-layer development object are determined.

Then, for each layer, the weighted average porosity coefficient Kp.av.v is determined. and weighted average oil saturation coefficient Kn.av.v. according to the formulas:

Kp.av.vz. = ((hi1 * Kп1) + (hi2 * Kп2) +…+ (hin * Kпn)) / (hi1+ hi2+…+ hin), fractions of units,

where hi1 is the vertical thickness of the first oil-saturated layer from the roof of the layer, hin is the vertical thickness of the last oil-saturated layer from the roof of the layer, Kp1...Kпn is the coefficient of open porosity in this layer.

Book average weight = ((hi1 * Kн1) + (hi2 * Kн2) +…+ (hin * Kнn)) / (hi1+ hi2+…+ hin), fractions of units,

where hi1 is the vertical thickness of the first oil-saturated layer from the roof of the layer, hin is the vertical thickness of the last oil-saturated layer from the roof of the layer, Kn1...Knn is the oil saturation coefficient in this layer.

Next, the effective radius of the formation is determined separately for each layer using the formula:

Ref. = (Kn.av.v. * Kn.av.v. * (hi1+ hi2+…+ hin)), m.

This determination of the effective radius of the formation makes it possible to take into account at the design stage the main parameters of the filtration and capacitance properties of each layer of a multi-layer development object, which influence the displacement characteristics of mobile oil reserves in the drainage zone of a horizontal well and allow the ranking of layers in the quantitative ratio of participation in the selection of reserves of the development object, as a consequence create a refined project for the development of a multi-layer facility, leading to a uniform and high rate of reserve selection at a multi-layer development facility.

Next, the effective share of each layer is determined using the formula:

Cef. = (Ref. / (Ref1+ Ref2+ ... + Refn)), fraction of units,

where Ref1…Refn is the effective radius in each layer.

The effective fraction of the reservoir makes it possible to estimate the probable potential of mobile oil reserves in the drainage zone of the fraction of the horizontal wellbore of the producing well in each formation. The higher the effective fraction of the formation, the more mobile reserves it contains.

Next, determine the effective length of opening of each layer using the formula: Lef. = Cef. * Lgs, m,

where Lгс is the length of the horizontal wellbore of the production well, providing economically viable recoverable oil reserves.

Determining the effective length of opening of each layer divides the design length of the horizontal wellbore of a production well into zones with the distribution of the extraction of oil reserves in each layer of a multi-layer development object; taking these zones into account during development ensures uniform production of reserves during the operation of the well. It also eliminates the breakthrough of underlying or injected water through individual layers of a multi-layer reservoir with subsequent watering of the resulting product.

After that, a horizontal well is drilled, taking into account the effective penetration lengths of each layer, and its operation is carried out.

Example of practical application.

Based on the results of exploratory drilling, a multi-layer development target was previously identified.

We determined economically viable recoverable oil reserves for one design horizontal production well of 80 thousand tons of oil.

We designed a production well with a horizontal trunk length of 500 m, providing economically viable recoverable oil reserves.

Next, we determined the coefficients of open porosity Kp, oil saturation Kn and vertical thickness hi of oil-saturated interlayers in each layer of the multi-layer development object. The results are shown in the table.

Then, for each formation, the weighted average porosity coefficient Kp.av.vz and the weighted average oil saturation coefficient Kn.av.vz were determined. The results are shown in the table.

Next, the effective formation radius Ref was determined separately for each layer. The results are shown in the table.

Next, we determined the effective fraction of each layer Kef. The results are shown in the table.

Next, we determined the effective penetration length of each layer Leff. The results are shown in the table.

Table. Results of the method

Vertical thickness of oil-saturated layers in the formation hi, m Open porosity coefficient Kp, fractions of units Oil saturation coefficient Kn., fraction of units Weighted average porosity coefficient Kp.av.v., fractions of units Weighted average oil saturation factor Kn.av.v., fractions of units Effective formation radius, m. Effective reservoir fraction,
shares of units Effective length of formation penetration, m. Layer 1 1.3 0.122 0.55 0.142 0.732 0.906 0.21 103 3.3 0.15 0.766 1 0.131 0.732 3.1 0.146 0.773 Layer 2 4.8 0.116 0.628 0.115 0.611 1,190 0.27 136 1.7 0.139 0.693 3.8 0.118 0.648 0.8 0.066 0.497 5.9 0.111 0.564 Layer 3 0.7 0.083 0.491 0.099 0.717 1.535 0.35 175 4 0.099 0.735 3.4 0.109 0.753 1.6 0.093 0.733 1.7 0.097 0.735 0.6 0.076 0.68 1.8 0.093 0.696 5.9 0.106 0.722 1.9 0.086 0.686 Layer 4 0.6 0.12 0.634 0.122 0.754 0.755 0.17 86 3 0.122 0.76 0.6 0.094 0.739 1.8 0.14 0.78 2.2 0.116 0.761

After that, a horizontal well was drilled, taking into account the effective penetration lengths of each layer, and its operation was carried out.

A horizontal well drilled using this technology with a comparable flow rate to a well drilled using a different technology with opening a section of a multi-layer oil reservoir development object worked with low water cut for 8 years and produced 80 thousand tons of oil, a horizontal well opened a section using a different technology worked for 4 years with low water cut and abruptly watered up to 95% along the section of the shaft that opened formation 2, the accumulated production amounted to 40 thousand tons. The well was decommissioned for economic reasons.

Thus, the proposed method increases the efficiency of the method for developing a multi-layer oil deposit with a horizontal well by increasing the accuracy of the optimal placement of a horizontal well by creating a refined project for the development of a multi-layer object, which takes into account the main parameters of the filtration and reservoir properties of each layer, and evaluates the probable potential of moving oil reserves in the zone drainage of the share of the horizontal wellbore of the production well in each layer, the projected length of the horizontal wellbore of the production well is divided into zones with the distribution of the extraction of oil reserves in each layer, which makes it possible to evenly produce oil reserves in the drainage zone and maintain high rates of extraction of reserves from the development site.

Claims (20)

A method for developing a multi-layer oil deposit with a horizontal well, including designing the trajectory of a horizontal wellbore of a production well, drilling a horizontal wellbore of a production well, characterized in that, based on the results of exploratory drilling or data from a geological model of the drilling site for a horizontal production well, a multi-layer development object is identified and economically viable recoverable oil reserves for one design horizontal production well, design a production well with a horizontal trunk length, then determine the coefficients of open porosity Kp, oil saturation Kn and the vertical thickness hi of oil-saturated layers in each layer of a multi-layer development object, then for each layer the weighted average porosity coefficient Kp is determined. avg. and weighted average oil saturation coefficient Kn.av.v. according to the formulas: Kp.av.vz. = ((hi1 * Kп1) + (hi2 * Kп2) +…+ (hin * Kпn)) / (hi1+ hi2+…+ hin), fractions of units, where hi1 is the vertical thickness of the first oil-saturated layer from the roof of the layer, hi2 – vertical thickness of the second oil-saturated layer from the roof of the layer, hin is the vertical thickness of the last oil-saturated layer from the top of the layer, Kp1…Kpn is the coefficient of open porosity in a given layer, and Kn.sr.vz. = ((hi1 * Kн1) + (hi2 * Kн2) +…+ (hin * Kнn)) / (hi1+ hi2+…+ hin), fractions of units, where hi1 is the vertical thickness of the first oil-saturated layer from the roof of the layer, hi2 – vertical thickness of the second oil-saturated layer from the roof of the layer, hin is the vertical thickness of the last oil-saturated layer from the top of the layer, Kn1…Knn – oil saturation coefficient in a given layer, Next, the effective radius of the formation is determined separately for each layer using the formula: Ref. = (Kn.av.v. * Kn.av.v. * (hi1+ hi2+…+ hin)), m, Next, the effective share of each layer is determined using the formula: Cef. = (Ref. / (Ref1+ Ref2+ ... + Refn)), fraction of units, where Ref1…Refn is the effective radius in each layer, Next, the effective penetration length of each layer is determined using the formula: Lef. = Cef. * Lgs, m, where Lгс is the length of the horizontal wellbore of the production well, providing economically viable recoverable oil reserves, after which a horizontal well is drilled, taking into account the effective penetration lengths of each layer, and its operation is carried out.