CN113898323A

CN113898323A - Offshore oil and gas field underwater production system and design method thereof

Info

Publication number: CN113898323A
Application number: CN202010577037.6A
Authority: CN
Inventors: 徐孝轩; 邱伟伟; 王祺; 陈从磊; 张涛; 司江伟
Original assignee: China Petroleum and Chemical Corp; Sinopec Exploration and Production Research Institute
Current assignee: China Petroleum and Chemical Corp; Sinopec Exploration and Production Research Institute
Priority date: 2020-06-22
Filing date: 2020-06-22
Publication date: 2022-01-07
Anticipated expiration: 2040-06-22
Also published as: CN113898323B

Abstract

The embodiment of the invention discloses an offshore oil and gas field underwater production system and a design method thereof. The design method of the offshore oil and gas field underwater production system comprises the following steps: selecting the number and the pipe diameter of the stand pipes according to the obtained crude oil yield of the deepwater oil field; selecting a mooring point of the FPSO according to the acquired distribution condition of the underwater well mouth; obtaining feasible layout points of the FPSO based on the mooring points of the FPSO; performing well mouth grouping on the FPSO feasible layout points and the obtained cluster well manifold quantity to obtain grouped data, and performing layout on the obtained cluster well manifolds; obtaining a connection relation between the FPSO and the cluster well manifold based on the grouped data and the cluster well manifold after layout; the FPSO is connected to the cluster well manifold based on its connection to the cluster well manifold and the selected riser. The purpose of improving the design evaluation accuracy and comprehensiveness of the offshore oil and gas field underwater production system is achieved.

Description

Offshore oil and gas field underwater production system and design method thereof

Technical Field

The invention belongs to the technical field of offshore oil engineering, and particularly relates to an offshore oil and gas field underwater production system and a design method thereof.

Background

An underwater production system is a core part in deepwater oil and gas field development, and is a seabed system consisting of a plurality of components and used for oil and gas production at water depth which is not suitable for conventional fixed or base type platform installation. Typically, a subsea production facility primarily comprises a subsea tree, a subsea manifold, a pipe termination manifold, export pipelines, and subsea connection systems, such as risers, jumpers, connectors, etc.

In the development of large and medium-sized deepwater oil fields with a large number of underwater well heads, the underwater well heads are generally connected to a plurality of cluster well manifolds respectively for development together so as to produce the whole oil field. The underwater Christmas tree installed on the underwater wellhead is sequentially connected to the cluster well manifolds in a tie-back mode of a jumper pipe-PLET-submarine pipeline-PLET-jumper pipe-cluster well manifolds, and then the cluster well manifolds are connected with one another through submarine pipelines and are uniformly conveyed to the floating platform. The optimal design of the underwater production system is a crucial part in the design of a deepwater oil and gas field development scheme. The optimized design of the underwater production system comprises the layout of cluster well manifolds, well mouth grouping design and the design of a connection scheme between the cluster well manifolds and PLEM.

At present, companies and scholars at home and abroad optimize the layout of submarine pipelines and the layout of cluster well manifolds of an underwater production system. In 2012 and 2014, respectively, the china oil university (beijing) proposes an optimization method [ y.wang, m.duo, m.xu, d.wang, w.feng, a Modeling model for optimizing the layout of the cluster well manifolds in the layout of the subsea wellheads and the cluster well manifolds with the lowest submarine pipeline cost as a target [ y.wang, m.duo, j.feng, d.mao, m.xu, s.f. essential, s.2012,36: 26-35 ] and an optimization method [ y.wang, m.duo, j.feng, d.mao, m.xu, s.f. essential, g for optimizing the layout of the cluster well manifolds with the lowest submarine pipeline cost as a target [ y.wang, m.duo, j.feng, d.mao, m.xu, s.f. optimized for optimizing the layout of the cluster well manifolds, i.e. a set of optimization methods [ 80.46.2014 ] which are integrated and integrated. The basic principle of the optimization method is as follows: firstly, wellhead grouping and cluster well manifold layout are continuously changed, and a design scheme with the lowest sea pipe cost is selected as an optimal scheme from a plurality of enumerated schemes. And then, continuously changing the connection relation among the cluster well manifolds on the basis of the layout design of the cluster well manifolds, and selecting a cluster well manifold connection scheme with the lowest sea pipe cost as an optimal scheme on the basis of ensuring that a closed loop is not formed.

In the process of implementing the invention, the inventor finds that at least the following problems exist in the prior art

In the existing scheme of the underwater production system, the lowest cost of a submarine pipeline is preferably taken as a preferred target, the layout of the submarine pipeline is optimized, only the deviation between the preferred single target with the lowest cost of the submarine pipeline and the actual engineering is considered, the safety and the high efficiency of the underwater production system and the cost of the whole underwater production system are not considered, and the preferred result has certain deviation from the actual engineering, so that the underwater production system has limitation.

Disclosure of Invention

In view of this, the embodiment of the invention provides an offshore oil and gas field underwater production system and a design method thereof, which at least solve the problem that in the prior art, only the single target with the lowest cost of a submarine pipeline is considered to be preferred and have deviation with the actual engineering, so that the evaluation result is inaccurate and incomplete.

In a first aspect, an embodiment of the present invention provides a method for designing an offshore oil and gas field subsea production system, including:

selecting the number and the pipe diameter of the stand pipes according to the obtained crude oil yield of the deepwater oil field;

selecting a mooring point of the FPSO according to the acquired distribution condition of the underwater well mouth;

obtaining feasible layout points of the FPSO based on the mooring points of the FPSO;

performing well mouth grouping on the FPSO feasible layout points and the obtained cluster well manifold quantity to obtain grouped data, and performing layout on the obtained cluster well manifolds;

obtaining a connection relation between the FPSO and the cluster well manifold based on the grouped data and the cluster well manifold after layout;

the FPSO is connected to the cluster well manifold based on its connection to the cluster well manifold and the selected riser.

In a second aspect, the embodiment of the invention also provides an offshore oil and gas field underwater production system, which is designed by adopting the design method of any one of the first aspect.

The invention selects the number and the pipe diameter of the stand pipes according to the acquired crude oil yield of the deepwater oil field, selects the mooring points of the FPSO according to the acquired distribution condition of the underwater wellhead, obtains the feasible layout points of the FPSO based on the mooring points of the FPSO, performing wellhead grouping on the feasible layout points of the FPSO and the acquired cluster well manifold quantity to obtain grouped data, laying out the obtained cluster well manifold, obtaining the connection relation between the FPSO and the cluster well manifold based on the grouped data and the laid-out cluster well manifold, in the design, optimization scheme design and optimization are carried out on the mooring position of the FPSO, the pipe diameter and the number of the stand pipes, the pipe diameter of the submarine pipeline, the grouping of the wellheads, the layout of the cluster well manifold and the connection relation between the cluster well manifold and the FPSO, therefore, the safety and the high efficiency of the design of the offshore oil and gas field underwater production system are improved, and the purposes of improving the design evaluation accuracy and comprehensiveness of the offshore oil and gas field underwater production system are achieved.

Comprehensively considering a plurality of underwater equipment such as a cluster well manifold, a submarine pipeline, a jumper pipe, a PLET, a riser base plate, a flexible riser and the like, carrying out optimization scheme design and optimization on the mooring position of the FPSO, the pipe diameter and the number of the riser, the pipe diameter of the submarine pipeline, well mouth grouping, the layout of the cluster well manifold and the connection relation between the cluster well manifold and the FPSO, and carrying out multi-target comprehensive evaluation on economy, safety, high efficiency and the like.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.

FIG. 1 shows a schematic layout of a subsea production system according to an embodiment of the present invention;

FIG. 2 illustrates a seafloor plan partitioning diagram of one embodiment of the invention;

FIG. 3 illustrates a diagram of all FPSO possible layout points for one embodiment of the present invention;

FIG. 4 illustrates a manifold layout and wellhead grouping scheme of one embodiment of the present invention;

FIG. 5 illustrates a schematic diagram of a manifold-FPSO connection scheme according to an embodiment of the invention;

FIG. 6 illustrates a schematic view of a synthetic index optimized subsea production system design in accordance with an embodiment of the present invention;

FIG. 7 shows a schematic subsea wellhead distribution diagram in accordance with an embodiment of the present invention.

Detailed Description

Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein.

FPSO (Floating production storage and offloading): offshore oil and gas processing plants.

A design method of an offshore oil and gas field underwater production system comprises the following steps:

Optionally, the selecting the number and the pipe diameter of the stand pipes according to the obtained crude oil production of the deepwater oil field includes:

determining the maximum engineering pipe diameter and the minimum engineering pipe diameter of the stand pipe;

determining a maximum riser number and a minimum riser number based on the maximum engineering pipe diameter and the minimum engineering pipe diameter;

determining the number of a plurality of stand pipes and the matching scheme of the pipe diameters based on the determined maximum engineering pipe diameter, the determined minimum engineering pipe diameter, the determined maximum stand pipe number and the determined minimum stand pipe number;

and selecting an optimal collocation scheme according to the collocation scheme of the number and the pipe diameter of the plurality of stand pipes.

Optionally, the determining a collocation scheme of a plurality of riser numbers and pipe diameters based on the determined maximum engineering pipe diameter, minimum engineering pipe diameter, maximum riser number and minimum riser number includes:

calculating the optimal pipe diameter corresponding to the number of the stand pipes;

searching the actual engineering pipe diameter meeting the optimal pipe diameter requirement in a pre-configured equipment cost library;

calling the unit length cost of the corresponding engineering actual pipe diameter;

calculating the related cost of the number of the stand pipes and the pipe diameter scheme based on the unit length cost;

and determining the number of the stand pipes and the matching scheme of the pipe diameters based on the related cost.

Optionally, determining the maximum number of risers and the minimum number of risers based on the maximum engineering pipe diameter and the minimum engineering pipe diameter includes:

determining a maximum riser number and a minimum riser number using the following formulas;

wherein R is_numMAXFor maximum number of risers, R_numMINIs the minimum number of risers, R_dmMAXIs the maximum engineering pipe diameter of the vertical pipe, R_dmMINFor minimum engineering pipe diameter of riser, Oil_PCrude oil production;

and/or

The optimal pipe diameter corresponding to the number of the stand pipes is calculated, and the method comprises the following steps:

for the ith feasible riser number, Oil_PIn order to obtain the yield of crude oil,

is the best pipe diameter.

Optionally, the selecting a mooring point of the FPSO according to the acquired distribution of the underwater wellheads includes:

determining the boundary of an underwater wellhead;

setting a plurality of point coordinates in an area within the boundary range;

respectively calculating the distance from each point coordinate to each underwater wellhead;

point coordinates not meeting FPSO berthing requirements are excluded based on the distance.

Optionally, the performing wellhead grouping on the FPSO feasible layout points and the obtained cluster well manifold number to obtain grouped data, and performing layout on the obtained cluster well manifold includes:

determining a number limit for a cluster well manifold;

numbering the number of all possible manifolds based on the number limit;

performing wellhead grouping, manifold layout and optimal design of a connection scheme on all the manifold quantity and the FPSO mooring point combination scheme based on the numbered manifold quantity to obtain an optimal design scheme;

determining the maximum value and the minimum value of the sea pipe distance, the total tie-back distance and the cluster well manifold in all the optimized design schemes;

respectively calculating the marine vessel distance, the total tie-back distance and the fuzzy normalization coefficient of the cluster well manifold in all the optimized design schemes based on the maximum value and the minimum value;

scoring the influence factors in the optimized design scheme to obtain a scoring result;

calculating the average value of the scoring result to obtain a judgment matrix;

calculating elements in the judgment matrix to obtain the weight of the influence factors;

determining the maximum value and the minimum value of the influence factors;

calculating fuzzy normalization coefficients of the influence factors of each design scheme based on the weight, the maximum value and the minimum value, and calculating fuzzy-gray correlation degrees of each scheme;

a preferred design is derived based on the degree of blur-grey correlation.

Optionally, the performing, based on the numbered number of manifolds, wellhead grouping, manifold layout and optimal design of a connection scheme on all the number of manifolds and the FPSO anchor point combination scheme includes:

randomly arranging cluster well manifolds;

calculating and carrying out wellhead grouping and optimization design of the layout of the cluster well manifolds based on the result of randomly arranging the cluster well manifolds;

calculating the distance from the underwater well mouth in each well mouth group to the corresponding cluster well manifold to obtain a tie-back pipeline of each underwater well mouth, and obtaining the total distance of the tie-back pipelines based on the tie-back pipelines of each underwater well mouth;

renaming the manifold and wellhead groups, and renaming all feasible FPSO anchor points; to;

and optimally designing a wellhead group and a manifold and FPSO connection mode of all feasible FPSO mooring points based on the total distance of the tieback pipelines, the renamed manifold and the renamed FPSO mooring point.

Optionally, the calculating to perform optimization design of wellhead grouping and cluster well manifold layout includes:

determining the distance between each manifold and the wellhead;

storing the distance between the manifold and the wellhead into a comparison matrix;

storing underwater wellheads into a wellhead group based on the comparison matrix;

renaming underwater wellheads in the wellhead group;

determining the centroids of the wellhead groups based on the renamed underwater wellheads;

and judging whether the centroid of each wellhead group is the same as the position of the cluster well manifold.

Optionally, the optimally designing the wellhead group and the manifold and FPSO connection mode of all feasible FPSO mooring points based on the total distance of the tieback pipelines, the renamed manifold and the renamed FPSO mooring point includes:

establishing a manifold and FPSO connection scheme storage matrix;

initializing two matrices for storing endpoints;

connecting the cluster well manifold and the FPSO together in an optimal manner based on the storage matrix and the two matrices for storing endpoints to obtain a connection result;

calculating a total subsea pipeline length based on the connection results;

determining an optimal theoretical pipe diameter of the subsea pipeline based on the total length of the subsea pipeline;

calling an optimal engineering pipe diameter and unit length cost which accord with a theoretical optimal pipe diameter in a submarine pipeline cost matrix;

calculating the optimal theoretical pipe diameter of the tie-back pipeline based on the optimal engineering pipe diameter and the unit length cost;

retrieving the optimal tieback pipeline pipe diameter and unit cost in a submarine pipeline cost matrix based on the optimal theoretical pipe diameter of the tieback pipeline;

evaluating the economy of optimization design of manifolds and FPSO connection modes of all feasible mooring points of the FPSO based on the pipe diameter of the tie-back pipeline and unit cost;

and evaluating the safety of optimization design of the manifolds and the FPSO connection modes of all feasible mooring points of the FPSO based on the pipe diameter of the tie-back pipeline and unit cost.

An offshore oil and gas field underwater production system is designed by adopting the design method.

The first embodiment is as follows:

the basic parameter system involved in the method is described in detail as follows:

(1) expression form of underwater well head

Setting underwater well mouth as W₁，W₂，W₃，…，W_nWhere n is the number of subsea wellheads, its expression also expresses its coordinates. Taking a deepwater oil field as an example, the underwater wellhead distribution is shown in Table 1, wherein

While all subsea wellhead coordinates are stored in the matrix W, i.e.:

TABLE 1 deepwater oilfield underwater wellhead coordinates (unit: km)

(2) Expression form of cluster well manifold

Let the expression of k cluster well manifolds be M₁，M₂，M₃，…，M_kThe expression of which also represents its coordinates, i.e.

Let k be the maximum and minimum numbers of cluster well manifolds respectively_MAX，k_MIN。

(3) Expression patterns of well head groups

As shown in FIG. 1, let all and manifolds M_iThe underwater well head connected with i-1, 2,3, …, k is well head group G_iI-1, 2,3, …, k, whose index k is consistent with the index of the cluster manifold, i.e., its number is consistent with the cluster manifold, and its expression also represents the cluster manifold M_iConnected well head coordinate storage matrices, i.e. if cluster well manifold M₁With underwater well head W₁，W₂，W₃，W₄And when the connection is carried out:

simultaneously, the number of underwater wellheads in the well head group is G_num。

(4) Related expression of risers

The number of the set pipes is R_numSetting the maximum value and the minimum value of the number of the tubes as R respectively_numMAX，R_numMINSetting the pipe diameter of the pipe to be R_dm(in)。

(5) Expression forms of FPSO

As shown in fig. 1, FPSO is FPSO ═ (x)_FPSO，y_FPSO) The expression also represents the coordinates of the FPSO anchor point.

(6) Expression form of submarine pipeline between manifold and FPSO

In the method, when the connection mode between the cluster well manifold and the FPSO is optimized, the FPSO is regarded as the (k +1) th cluster well manifold, namely

If the ith cluster well manifold and the jth cluster well manifold are connected, the subsea pipeline connecting the two is PIPDIS_ij(km) number of subsea pipelines PIP_num(II) the pipe diameter of the submarine pipeline which connects the cluster well manifold and the FPSO is PIP_dm(in)。

(7) Expression form of tie-back pipeline between underwater wellhead and cluster well manifold

If the ith underwater wellhead is connected with the jth cluster well pipe sink, the tie-back distance is TBDIS_ij(km) pipe diameter TB_dm(in)。

(8) Input parameter expression form

Let crude Oil production be Oil_p(kbbl/d), Water depth is set as Water_D(m) the development period is P_time(year).

(9) Expression form of prefabricated database

Before starting optimization calculation, part of the equipment cost database needs to be prefabricated in an algorithm in a matrix form, and the subsea pipeline cost matrix is set as

Each row of the matrix represents various parameters of a device model, i.e.

The cost matrix of the flexible vertical pipe is

The cost matrix for setting cluster well manifolds is

The method comprises the following steps:

firstly, optimizing the number and the pipe diameter of the stand pipes according to the crude oil yield of the deepwater oil field:

step 1.1, confirmAnd (3) determining the maximum engineering pipe diameter of the riser, namely the maximum pipe diameter of all risers available for use in engineering. Riser cost matrix

As shown in (1-1), the second column of the matrix represents the pipe diameter of the riser, the maximum value of all the elements in the column is the maximum pipe diameter, and is set as R_dmMAX(in), in this case R_dmMAX＝12in。

Step 1.2, determining the minimum engineering pipe diameter of the stand pipe, namely the minimum pipe diameter of all stand pipes available for use in engineering. The minimum value of all elements in the second column of the matrix (1-1) is set as R_dmMIN(in), i.e. the minimum engineering pipe diameter, in this case R_dmMIN＝8in。

Step 1.3, determining the maximum number of the stand pipes and the minimum number of the stand pipes, and calculating the maximum number and the minimum number of the stand pipes by using the formulas (1-2) (1-3) respectively, wherein

And

representing the upper and lower rounding in mathematical language, respectively, in this case the maximum riser number is 5 and the minimum riser number is 3. (1-2) (1-3) the following:

R_numMAX-maximum number of risers, root;

R_numMIN-minimum number of risers, root;

R_dmMAX-riser maximum engineering pipe diameter, in;

R_dmMIN-riser minimum engineering pipe diameter, in;

Oil_Pcrude oil production, kbbl/d (thousand barrels per day).

And 1.4, determining all feasible riser quantity-pipe diameter matching schemes. For all feasible vertical pipe numbers in sequence

The calculation from step 1.4.1 to step 1.4.4 is carried out, the number of the feasible risers in the present case is respectively

And 1.4.1, calculating the optimal pipe diameter corresponding to the number of the stand pipes. Calculating the number of feasible risers by using the formula (1-4)

Corresponding optimal pipe diameter

Namely:

i＝1，2，…，(R_numMAX-R_numMIN)；

the corresponding optimal pipe diameter in;

-the ith number of possible risers, root;

Oil_Pcrude oil production, kbbl/d (thousand barrels per day).

R_numMAXMaximum number of risersAmount, root;

R_numMIN-minimum number of risers, root;

and 1.4.2, searching the actual engineering pipe diameter meeting the requirement of the optimal pipe diameter in an equipment cost library. Will matrix

Greater than or equal to and closest to (1-1)

Redefining the riser diameter as

That is to say, the

Is updated to be equal to or greater than in the second column of the matrix (1-1)

Of the elements of (1), if

Is 8.5, all elements in the second column of the contrast matrix (1-1) are found 10 and 12 to meet the above-mentioned screening conditions, and will eventually be

Updated to the minimum of the two elements, i.e.

And 1.4.3, calling the unit length cost of the corresponding engineering actual pipe diameter. Will renew the pipe diameter of the stand pipe

The corresponding riser unit cost is defined as

Instantaneous matrix

(1-1) in

The first column element of the row equals

In this case, if

Then

And 1.4.4, calculating the related cost of the riser number-pipe diameter scheme. Calculation of riser associated costs using equations (1-5)

Riser related costs, i.e. all costs related to number of risers, pipe diameter, length, and storing the costs and the corresponding number of risers and riser pipe diameter in a matrix (1-6):

-riser related costs, USD;

-the ith number of possible risers, root;

the corresponding optimal pipe diameter in;

corresponding riser unit cost, USD/m;

Water_D-water depth, m;

step 1.5, the optimal riser number-pipe diameter scheme is optimized. The iterative loop from step 1.4.1 to step 1.4.4 is now complete and all the RISERs are processed_i，i＝1，2，…，(R_numMAX-R_numMIN) Storage to matrix RISER_pattern(1-7), cost of riser-related

The smallest riser scheme is taken as a final scheme, and the number, the pipe diameter and the cost of the risers are renamed to R_num，R_dm，RISER_COSTI.e. the minimum of the elements of the third column of the matrix (1-7) and the first and second column of the row in which they are located are respectively made equal to the RISER-related cost RISER_COSTOptimum number of risers R_numAnd the optimum pipe diameter R of the riser_dm。

And in the second step, optimizing the mooring point of the FPSO according to the distribution condition of the underwater well head:

and 2.1, determining the boundary of the underwater wellhead. Respectively finding out the maximum horizontal coordinate X of all underwater well heads_MAXMaximum ordinate Y_MAXMinimum abscissa X_MINAnd a minimum ordinate Y_MINI.e. the maximum and minimum values of the first and second columns of the matrix W (0-1) are determined using the methods described in step 1.1 and step 1.2, respectively.

And 2.2, setting a plurality of point coordinates in the area within the boundary range. With (X)_MIN-3.5，Y_MIN-3.5)，(X_MIN-3.5，Y_MAX+3.5)，(X_MAX+3.5，Y_MIN-3.5)，(X_MAX+3.5，Y_MAX+3.5)

Four points are used as end points, the seabed plane is divided at intervals of 1km (as shown in figure 2), and all intersection points are stored in a matrix FPSO_base(2-1)。

And 2.3, respectively calculating the distance from each point coordinate to each underwater wellhead. FPSO matrix_base(2-1) points are FPSO_iI-1, 2, …, 3016, calculating each FPSO separately_iWith each underwater well head W in the matrix W (0-1)_jJ equals 1, 2, …, 20 distance L_ijNamely:

L_ij-the i-th intersection point FPSO_iWith jth underwater well head W_jDistance between, km;

-intersection point FPSO_iThe abscissa of (c), km;

-intersection point FPSO_iKm, km;

subsea wellhead W_jThe abscissa of (c), km;

subsea wellhead W_jKm, respectively.

And 2.4, excluding the point coordinates which do not meet the FPSO mooring requirement. If a certain FPSO_iWith each underwater well head W_jJ equals 1, 2, …, 20 distance L_ijIf j is greater than or equal to 3.5km, then the point is retained, otherwise the point is retained in the FPSO matrix_baseAnd (2-1) deleting the point, wherein all the finally obtained points are the feasible layout points of the FPSO (shown in figure 3).

And thirdly, sequentially carrying out wellhead grouping, cluster well manifold layout and optimization of FPSO-cluster well pipe manifold connection relation on all FPSO feasible layout points and the number of cluster well manifolds. This step can be achieved by the following detailed steps:

and 3.1, determining the number limit of cluster well manifolds. Since the maximum well slot number and the minimum well slot number of the cluster well pipe are 14 and 4 respectively, the maximum number k of the cluster well pipe is calculated by using the formula (3-1) and the formula (3-2) respectively_MAXAnd the minimum number k_MINWherein

And

respectively representing the upper round and the lower round in mathematical language, taking the deepwater oil field with 20 underwater wellheads as an example, the maximum number k of cluster well manifolds _MAX5 minimum number k_MINAs 2, formula (3-1) and formula (3-2) are as follows:

k_MAX-a maximum number, one, of cluster well manifolds;

k_MIN-a minimum number of cluster well manifolds;

n-number of underwater wellheads.

Step 3.2, numbering all feasible manifold quantities, and defining all feasible manifold quantities as k_i，i＝1，2，…，(k_MAX-k_MIN+1), if k_MAX＝5，k_MINK when 2 is equal to₁，k₂，…，k₄＝2，3，4，5。

And 3.3, performing wellhead grouping, manifold layout and optimized design of a connection scheme on the combined scheme of the number of all manifolds-the FPSO anchor points. For all feasible cluster well manifolds k in turn_iI is 1, 2, …, 4, the following calculation of step 3.3.1 to step 3.3.6 is performed;

step 3.3.1, randomly arranging cluster well manifolds. Let k equal to k _i1, 2, …, 4, randomly collecting k cluster wells M_jJ-1, 2,3, … k is disposed in a subsea production system.

And 3.3.2, performing optimization design on the layout of the wellhead groups and the cluster well manifolds by using the calculation from the step 3.3.2.1 to the step 3.3.2.7.

At step 3.3.2.1, the distance between each manifold and the wellhead is determined. Calculating each underwater well head W by using the formula (3-3)_iI 1, 2,3, …, n and each cluster manifold M_jJ is the distance TBDIS between 1, 2,3, …, k_ijNamely:

i＝1，2，…，n，j＝1，2，…，k；

TBDIS_ijith subsea wellhead W_iAnd jth cluster well manifold M_jDistance between, km;

underwater well head W_iThe abscissa of (c), km;

underwater well head W_iKm, km;

cluster well manifold M_jThe abscissa of (c), km;

cluster well manifold M_jKm, km;

at step 3.3.2.2, the distance between the manifold and the wellhead is stored in a comparison matrix. Will be underwater well head W_iWith each cluster well manifold M₁，M₂，…，M_kDistance of TBDIS_ijI 1, 2, …, n, j 1, 2, …, k are stored in the contrast matrix TBDIS_compare(3-4) the ith row of the matrix represents the ith subsea well W_iDistance from k cluster manifolds, i.e.:

and step 3.3.2.3, storing the underwater well head nearby in a well head group. Sequentially distributing n underwater well heads to the well head group where cluster well manifold closest to the underwater well heads is located, if matrix TBDIS_compare(3-4) TBDIS in line 1₁₂At minimum, the 1 st underwater well head W₁Into the 2 nd wellhead group, i.e. matrix G₂(3-5)：

Underwater well head W₁The abscissa of (c), km;

underwater well head W₁Km, respectively.

At step 3.3.2.4, the subsea wellheads in the wellhead group are renamed. Let i-th well head group, i.e. matrix G_iI is 1, 2, …, k has the number of rows

Simultaneously numbering underwater well heads in each well head group again, and if the well head group G is not in the same group, numbering the underwater well heads₁In which 4 underwater well heads are stored, then the 4 underwater well heads are respectively renamed to W₁₁，W₁₂，W₁₃，W₁₄As shown in formulas (3-6), this nomenclature only changes the well head subgroup, matrix G_iI-1, 2, …, k element name in each row, without changing the original subsea wellhead name, i.e., W₁，W₂，…，W_nThe numbering of (a) is unchanged.

At step 3.3.2.5, the centroid of the wellhead group is determined. Respectively calculating the centroid of the underwater well head in each well head group by using the formulas (3-7), and naming the centroid of the ith well head group as newM_iI ═ 1, 2, …, k, formula (3-7) is as follows:

ith wellhead group G_iThe number of well heads is equal to the number of well heads;

—newM_ithe abscissa of (c), km;

—newM_ikm, km;

ith wellhead group G_iWell jth underwater well head W_ijThe abscissa of (c), km;

ith wellhead group G_iWell jth underwater well head W_ijKm, respectively.

At step 3.3.2.6, it is determined whether the centroid of each well head cluster is the same as the location of its cluster well manifold. Sequentially calculating the ith wellhead group G by using the formula (3-8)_iCluster well manifold M in_iWith its centroid newM_iThe distance between

If it is

If not 0, then let M_i＝newM_iOn the contrary M_iThe formula (3-8) is as follows:

i＝1，2，…，k；

-abscissa, km, of ith cluster manifold;

-ordinate, km, of ith cluster manifold;

-i th well head group centroid newM_iThe abscissa of (c), km;

-i th well head group centroid newM_iKm, km;

at step 3.3.2.7, it is determined whether to stop the iteration. Repeating the steps 3.3.2.1-3.3.2.6, if the step 3.10 is calculated, obtaining

Both are 0, the iterative loop is stopped.

And 3.3.3, calculating the total distance of the tieback pipelines. Respectively calculating the distance from the underwater well head in each well head group to the corresponding cluster well manifold by using the formula (3-9)

Calculating total wellhead tie-back distance TBDIS by using formula (3-10)_totalThe formula (3-9) (3-10) is as follows:

ith well head smallGroup G_iThe number of well heads is equal to the number of well heads;

TBDIS_ij-the distance, km, between the ith cluster well manifold and the jth subsea wellhead connected thereto;

ith cluster well manifold M_iThe abscissa of (c), km;

ith cluster well manifold M_iKm, km;

ith wellhead group G_iWell jth underwater well head W_ijKm, km;

and 3.3.4, renaming the manifold and the wellhead group. The cluster well manifold layout coordinate and the wellhead grouping scheme obtained by the calculation in the steps are renamed to M_kiI ═ 1, 2, …, k and G_kiI is 1, 2, …, k, where the subscript k indicates the number of cluster well manifolds in the plan, and i indicates the number of the manifold or wellhead group, i.e. the ith cluster well manifold or wellhead group in the plan, and the optimization results are shown in fig. 4 by taking 5 manifolds as an example.

Step 3.3.5, rename all feasible FPSO anchor points. Will matrix FPSO_baseEach row element in (2-1) is defined as

Wherein

And

respectively represent a matrix FPSO_baseThe ith row, 1 st and 2 nd column elements, i.e., the ith FPSO.

And 3.3.6, optimally designing the manifold-FPSO connection modes of all FPSO feasible mooring points, and evaluating the economy and the safety. Sequentially aiming all feasible mooring points of FPSO

The following calculation of steps 3.3.6.1 to 3.3.6.11 is performed.

Step 3.3.6.1, establish a manifold-FPSO Connection scheme storage matrix Connection_pattern(3-11). If there are 3 cluster well manifolds M₁，M₂，M₃Wherein M is₁And M₂Are connected to M₂To FPSO, M₃Connected to the FPSO, then the matrix Connection_pattern(3-11) As shown below, where the two numbers on each column are the subscripts of a pair of interconnected cluster well manifolds, 0 represents FPSO.

At step 3.3.6.2, two matrices V (3-12) and U (3-13) for storing endpoints are initialized. Order to

And stored in matrix V (3-12), and the remaining cluster manifolds in matrix U (3-13):

V＝[x_FPSO y_FPSO] (3-12)

x_FPSO-abscissa of FPSO anchor point, km;

y_FPSOlongitudinal of mooring points of FPSOCoordinates, km;

-abscissa, km, of cluster well manifold No. 1;

-ordinate, km, of cluster well manifold No. 1;

at step 3.3.6.3, the cluster manifold and the FPSO are optimally connected together using steps 3.3.6.3.1-3.3.6.3.4.

At step 3.3.6.3.1, the distance between all points in the two matrices V and U is calculated. Let i' th behavior in matrix V (3-12)

Let j' th behavior in matrix U (3-13)

And all V's are calculated respectively using the equations (3-14)_iAnd all U_jIs a distance of

That is, the distance between all points in the matrix V and all points in the matrix U is calculated in pairs:

-the distance, km, between the element of the ith row in matrix V and the element of the jth row in matrix U;

—V_ithe abscissa of (c), km;

—V_ikm, km;

—U_jthe abscissa of (c), km;

—U_jkm, km;

at step 3.3.6.3.2, two points with the smallest distance are selected and the matrix U and the matrix V are adjusted. All L are put together_compareijU corresponding to the minimum value of_jStoring the matrix V and renaming the matrix U and the matrix V using the naming method of step 3.3.6.3.1 if there are 3 cluster well manifolds and manifold M in the subsea production system₁The distance from the FPSO anchor point is the smallest, the above method can be described by the equations (3-15) (3-16):

at step 3.3.6.3.3, the connection scheme storage matrix is updated. Using the method of step 3.3.6.1 to mix M₁The Connection relation between the FPSO and the storage matrix Connection is stored in a manifold-FPSO Connection scheme storage matrix_patternSimultaneously separating the two

Stored in the third row of the matrix, the collective method is as follows (3-17):

at step 3.3.6.3.4, it is determined whether the iteration has stopped. If all the cluster well manifolds in the matrix U are stored in the matrix V, that is, when the matrix U is 0, the iteration is stopped, otherwise, the iteration is continued, and a connection scheme after the iteration is ended by taking 5 manifolds as an example is shown in fig. 5.

At step 3.3.6.4, the total subsea pipeline length is calculated. If the matrix Connection is obtained through several iterations_patternIf the number of columns is "a", the length between two points, which is the third column element of the matrix, is renamed to Li, i is 1, 2, …, a, and the matrix Connection is calculated using equation (3-18)_patternThe sum of the third row elements, i.e. the total length of the sea pipes PIPDIS connecting the FPSO to the cluster well manifold_totalThe formula (3-18) is as follows:

PIPDIS_total-total subsea pipeline distance, km, connecting the FPSO to the cluster well manifold;

L_i-length of the ith subsea pipeline, km;

a-number of subsea pipelines, root.

At step 3.3.6.5, the optimal theoretical pipe diameter of the subsea pipeline is determined. Oil from crude Oil production Using formula (3-19)_PCalculating optimal theoretical pipe diameter PIP of submarine pipeline_dmt：

PIP_dmt-optimal theoretical pipe diameter of the subsea pipeline, in;

Oil_Pcrude oil production, kbbl/d.

3.3.6.6, cost matrix of subsea pipelines

The optimal engineering pipe diameter and the unit length cost which accord with the theoretical optimal pipe diameter are called. Given subsea pipeline cost matrices

Column 1 represents the unit cost of the pipeline, column 2 represents the pipe diameter, column 3 represents the applicable water depth, and the matrix

All 2 nd columns in (1) are equal to or greater than PIP_dmtAnd the 3 rd row is more than or equal to the Water depth Water_DRow adding matrix of

Will matrix

The minimum in column 1 element is defined as PIP_priceDefine the column 2 element of the row in which it is located as PIP_dm。

Step 3.3.6.7, calculating the optimal theoretical pipe diameter TB of the tie-back pipeline by using the formula (3-20)_dmt：

TB_dmt-the optimal theoretical pipe diameter of the tie-back line, in;

Oil_Pcrude oil production, kbbl/d;

n-number of underwater well heads.

3.3.6.8, cost matrix of subsea pipeline using the same method as step 3.3.6.6

Middle search optimal tie-back pipeline diameter TB_dmAnd unit cost TB_price。

Step 3.3.6.9, the economics of the design are evaluated. Calculating the cost of each device or system in the underwater production system by using the formulas (3-21) to (3-36), and finally calculating the overall cost CAPEX of the design scheme, namely the economy of the scheme:

C₁＝CAPEX_Xtree＝n×10000000 (3-21)

C₂＝CAPEX_manifold＝k×5000000 (3-22)

C₃＝CAPEX_{PIPconnectors}＝(n+2k)×1680000 (3-23)

C₄＝CAPEX_UBconnectors＝n×124000+k×882000 (3-24)

C₅＝CAPEX_guidebase＝n×400000 (3-25)

C₆＝CAPEX_TB＝TBDIS_total×TB_price+n×128000 (3-26)

C₇＝CAPEX_leads＝(n+3k)×519000 (3-27)

C₈＝CAPEX_control＝n×1778500+10532000 (3-28)

C₉＝CAPEX_PIP＝2×PIPDIS_total×PIP_price (3-29)

C₁₀＝CAPEX_PLETS＝(2k+n)×5824000 (3-30)

C₁₁＝CAPEX_UB＝(PIPDIS_total+TBDIS_total)×819200 (3-31)

C₁₂＝CAPEX_RISER＝RISER_COST (3-32)

n-number of underwater well heads, ports;

k is the number of cluster well manifolds;

TBDIS_total-total length of loop back, km;

TB_price-cost of loop back on line unit length, USD/km;

PIPDIS_total-total subsea pipeline length, km;

PIP_price-subsea pipeline unit length cost, USD/km;

RISER_COST-riser related costs, USD;

C₁-subsea tree overall cost, USD;

C₂-cluster well manifold overall cost, USD;

C₃overall subsea connector cost, USD;

C₄-umbilical connector overall cost, USD;

C₅-subsea wellhead overall cost, USD;

C₆-wellhead tieback overall cost, USD;

C₇flying lead joint overall cost, USD;

C₈-overall cost of the subsea control system, USD;

C₉subsea pipeline overall cost, USD;

C₁₀-PLETs overall cost, USD;

C₁₁-umbilical overall cost, USD;

C₁₂flexible riser overall cost, USD;

C₁₃-transportation cost, USD;

C₁₄-installation cost, USD;

C₁₅-other costs, USD;

CAPEX-the overall cost of the subsea production system, USD.

Step 3.3.6.10, calculating the safety SAFE of the scheme by using the formula (3-37):

SAFE-safety coefficient;

t-development age, year;

PIPDIS_total-total subsea pipeline length, km;

TBDIS_total-total length of loop back, km;

at step 3.3.6.11, the optimal design data is integrated into the correlation matrix. The mooring position FPSO of FPSO is (x)_FPSO，y_FPSO) The number k of cluster well manifolds and the total tieback length TBDIS_totalPipe diameter TB of tie-back pipeline_dmTotal subsea pipeline length pipis_totalSubsea pipeline pipe diameter PIP_dmThe overall cost CAPEX and the safety coefficient SAFE of the underwater production system are stored in a matrix PATTERN, the scheme data of the top five of the economic ranking are shown in the table 2, and because more elements of each row in the matrix PATTERN cannot be shown in a file, the matrix PATTERN is transposed (exchanged in rows and columns) and is shown in the table 2.

TABLE 2 transposed PATTERN of the matrix PATTERN after the iteration is over

And 3.4, determining the maximum value and the minimum value of the sea pipe distance, the total tie-back distance and the cluster well manifold in all the optimized design schemes. After all iterations are finished, all the marine vessel distances PIPIS in the matrix PATTERN are compared_totalTotal tie-back distance TBDIS_totalAnd the number k of manifolds, and the maximum distance of the submarine pipe is named maxPIPDIS_totalThe minimum marine vessel distance is named as minPIPIS_totalThe maximum total tie-back distance is named maxTBDIS_totalThe minimum total tie-back distance is named minTBDIS_totalThe maximum number of manifolds is named maxk, the minimum number of manifolds is named mink.

And 3.5, respectively calculating the marine vessel distance, the total tie-back distance and the fuzzy normalization coefficient of the cluster well manifold in all the optimized design schemes. The EFF of high efficiency of each row (i.e. each design solution) in the matrix PATTERN is calculated in turn by using the equations (3-38) to (3-41), and is stored in the matrix PATTERN by using the method of step 3.3.6.11, wherein the equations (3-38) to (3-41) are as follows:

PIPDIS_total' -fuzzy normalization factor of the total length of the sea pipe;

TBDIS_total' -fuzzy normalization factor of the total tieback distance;

k' -fuzzy normalization coefficients of manifold quantity;

EFF — coefficient of efficiency;

maxPIPDIS_total-maximum marine vessel distance, km;

minPIPDIS_total-minimum marine vessel distance, km;

PIPDIS_total-marine vessel distance, km;

maxTBDIS_total-maximum tieback distance, km;

minTBDIS_total-minimum tieback distance, km;

TBDIS_total-tieback distance, km;

maxk — maximum number of manifolds;

mink — minimum number of manifolds;

k is the number of manifolds.

Step 3.6, setting the economy as an influence factor 1, the safety as an influence factor 2 and the high efficiency as an influence factor 3, and giving 10 experts of the underwater production system to score the three influence factors by using a 1-9 grade and reciprocal scale method thereof, wherein the 1-9 grade scale is shown in table 3:

table 31-9 scale schematic

Step 3.7, calculating the average value of the scores of the 10 experts to obtain a judgment matrix Q (3-42):

step 3.8, calculating the elements in the judgment matrix Q by using the formula (3-43) to obtain the weight Q of the three influencing factors₁，Q₂，Q₃：

Q_i-weight of ith influencing factor;

q_ij-a judgment element of the importance of the ith influencing factor relative to the jth influencing factor;

and 3.9, determining the maximum value and the minimum value of the economic coefficient, the safety coefficient and the high efficiency coefficient. Respectively naming the maximum and minimum values of CAPEX in the matrix PATTERN as maxCAPEX and minCAPEX by using the method in the step 3.4, respectively naming the maximum and minimum values of the safety coefficient SAFE as maxSAFE and minSAFE, and respectively naming the maximum and minimum values of the high-efficiency coefficient EFF as maxEFF and minEFF;

and 3.10, calculating fuzzy normalization coefficients of the economy, safety and high efficiency of each design scheme, and calculating the fuzzy-gray correlation degree of each scheme. The fuzzy-gray correlation degree of each design solution (i.e. each row of data of the matrix PATTERN) is calculated in turn by using equations (3-44) to (3-47) and stored into the matrix PATTERN by using step 3.3.6.11, wherein equations (3-44) to (3-47) are as follows:

CAPEX' -fuzzy normalization factor for solution economics;

SAFE' -fuzzy normalization coefficient of scheme security;

EFF' -scheme efficient fuzzy normalization coefficients;

AP-fuzzy-grey correlation;

maxCAPEX-maximum investment cost, USD;

minCAPEX-minimum investment cost, USD;

CAPEX-investment cost, USD;

maxSAFE — maximum value of security coefficient;

minSAFE-minimum value of safety coefficient;

SAFE-safety coefficient;

maxEFF — maximum value of coefficient of efficiency;

minEFF — coefficient of efficiency minimum;

EFF — coefficient of efficiency;

Q₁，Q₂，Q₃-weight of influencer 1, influencer 2, and influencer 3.

And 3.11, after all iterations are finished, comparing all schemes in the matrix PATTERN, wherein the scheme with the highest fuzzy-gray correlation degree is the scheme with the best comprehensiveness, wherein the data of the schemes with the top five fuzzy-gray correlation degrees are shown in the table 4, and the schematic diagram of the design scheme with the highest fuzzy-gray correlation degree is shown in the figure 6.

TABLE 4 top 5 schema data

Example two:

taking a certain deepwater oil field as an example to carry out the optimization design of an underwater production system, the deepwater oil field has the water depth of 2200m and 20 underwater well heads, the daily yield of crude oil is 20 ten thousand barrels (200kbbl/d), the detailed coordinates of the underwater well heads are shown in a table 5, and the distribution diagram of the underwater well heads is shown in a figure 7:

TABLE 5 deepwater oilfield underwater wellhead coordinates (unit: km)

Firstly, the pipe diameter and the number of the stand pipes are optimized according to the daily yield of crude oil in the deepwater oil field, and 3 stand pipes with 12 inches are obtained as the best stand pipe combination scheme.

All feasible FPSO mooring points are then determined (as shown in figure 3).

And finally, optimally designing the wellhead grouping, the cluster well manifold layout and the FPSO-manifold connection mode, and finally preferably selecting the optimal design scheme, wherein the data of the five schemes in the top ranking is shown in the table 6, and the scheme with the highest fuzzy-gray correlation degree is shown in the diagram of fig. 5.

TABLE 6 top 5 schema data

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A design method of an offshore oil and gas field underwater production system is characterized by comprising the following steps:

2. The offshore field subsea production system design method of claim 1, wherein said selecting the number of risers and the pipe diameter according to the obtained crude oil production of the deepwater field comprises:

3. The offshore field subsea production system design method according to claim 2, wherein said determining a number of risers and a collocation scheme of pipe diameters based on the determined maximum engineering pipe diameter, minimum engineering pipe diameter, maximum riser number and minimum riser number comprises:

4. The offshore field subsea production system design method according to claim 3, wherein said determining a maximum and minimum number of risers based on said maximum and minimum engineering pipe diameters comprises:

wherein R is_numMAXFor maximum number of risers, R_numMINIs a minimum riserNumber, R_dmMAXIs the maximum engineering pipe diameter of the vertical pipe, R_dmMINFor minimum engineering pipe diameter of riser, Oil_PCrude oil production;

and/or

is the best pipe diameter.

5. The offshore field subsea production system design method according to claim 1, wherein said selecting mooring points for the FPSO based on the obtained subsea wellhead distribution comprises:

determining the boundary of an underwater wellhead;

setting a plurality of point coordinates in an area within the boundary range;

6. The design method of subsea production system for offshore oil and gas field according to claim 1, wherein said grouping wellhead of feasible placement points of FPSO and number of cluster well manifolds obtained to obtain grouped data, and said arranging obtained cluster well manifolds comprises:

determining a number limit for a cluster well manifold;

numbering the number of all possible manifolds based on the number limit;

determining the maximum value and the minimum value of the influence factors;

a preferred design is derived based on the degree of blur-grey correlation.

7. The offshore field subsea production system design method according to claim 6, wherein said optimized design of wellhead grouping, manifold layout and connection scheme for all manifold quantities and FPSO anchor combination scheme based on numbered manifold quantities comprises:

randomly arranging cluster well manifolds;

8. The method of claim 7, wherein the calculating an optimized design of wellhead grouping and cluster well manifold layout comprises:

determining the distance between each manifold and the wellhead;

renaming underwater wellheads in the wellhead group;

9. The offshore field subsea production system design method according to claim 7, wherein said optimized design of the wellhead group and of the manifold and FPSO connection patterns for all FPSO feasible mooring points based on total tieback line distance, renamed manifolds and renamed FPSO mooring points comprises:

establishing a manifold and FPSO connection scheme storage matrix;

initializing two matrices for storing endpoints;

calculating a total subsea pipeline length based on the connection results;

10. An offshore oil and gas field subsea production system, characterized in that it is designed using the design method according to any of claims 1 to 9.