CN101592030A - A kind of control method of reasonable driving depth of offshore cluster well group risers - Google Patents

Abstract

The present invention relates to a kind of control method of reasonable driving depth of offshore cluster well group risers, it may further comprise the steps: 1) according to the seafloor soil characteristic data of position, well site, calculate the formula of drilling riser ultimate bearing capacity Q; 2), calculate drilling riser ultimate bearing capacity Q behind the efficiency of pile groups according to the distance between the cluster well group riser pipe _gFormula; 3) according to step 2), and, work as Q in conjunction with marine cluster well group well head loading force W _gDuring 〉=W, the reasonable hammer that obtains cluster well group riser pipe is gone into degree of depth h _eThe present invention can be according to the actual conditions of different waters seabottom geology and offshore wellhead spacing and well head load, determine reasonable driving depth of offshore cluster well group risers, satisfy the requirement of different waters cluster well group wellbore construction, both reduced and gone into the marine complex accident that the mud change in depth causes because of the cluster well riser pipe and take place, avoid waste economically again, reached not only safety but also economic purpose.

Description

A kind of control method of reasonable driving depth of offshore cluster well group risers

Technical field

The present invention relates to a kind of control method, especially a kind of control method of reasonable driving depth of offshore cluster well group risers.

Background technology

In the offshore oil exploration, the mud degree of depth of going into of drilling riser plays an important role for the exploration of whole oil, exploitation, if it is too small to go into the mud degree of depth, will cause the unstability of well head, marine complex accident such as sink; If it is excessive to go into the mud degree of depth, will cause waste economically.The mud degree of depth of going into for single drilling riser generally determines according to the character of seafloor soil, in different marine sites and sea conditions,

The mud degree of depth of going into for drilling riser requires also inequality.And present offshore drilling major part is the cluster well group, general well head spacing is between 1.5～2.0 meters, so little distance can cause riser pipe seafloor soil generation efficiency of pile groups between them in the piling construction process, the moisture content that causes soil between them descends, compactness increases, and ultimate bearing capacity increases, and riser pipe is hammered into shape into the degree of depth and reduced, construct if also go into the degree of depth according to the hammer of single pile riser pipe, can in the piling construction process, cause serious refusing hammer phenomenon into shape.Will certainly cause that like this hammering number in the work progress increases severely, construction period prolongs, and the operation on the sea expense increases, even can cause drilling riser to damage, and causes the generation of marine complex accident.So, how to determine that reasonable driving depth of offshore cluster well group risers becomes a problem that urgency is to be solved in the offshore oil exploration technology.

Summary of the invention

At the problems referred to above, the control method that the purpose of this invention is to provide a kind of reasonable driving depth of offshore cluster well group risers, to determine that the clump formula opens the group drilling well and hammer into shape into the degree of depth every conduit, avoid economic waste, reduce offshore drilling riser pipe piling construction and the marine accident that causes.

For achieving the above object, the present invention takes following technical scheme: a kind of control method of reasonable driving depth of offshore cluster well group risers, it is characterized in that: it comprises the steps: 1) hammer the seafloor soil parameter and the drilling engineering parameter of the position, well site that collects into depth control system into shape according to cluster well group drilling riser, the formula that calculates drilling riser ultimate bearing capacity Q is:

$Q=b_{1}D\·e^{a_{1}h}$

2), calculate drilling riser ultimate bearing capacity Q behind the efficiency of pile groups according to the distance between the cluster well group riser pipe _gFormula be:

$Q_g=b_1{D}^{c_1\frac{h}{L}}\·e^{a_{1}h}$

3) according to step 2), and, work as Q in conjunction with marine cluster well group well head loading force W _gDuring 〉=W, the reasonable hammer that obtains cluster well group riser pipe is gone into depth H _e

Then $h\≥\frac{L(\ln W-\ln b_1)}{c_1\ln D+{\mathrm{La}}_1};$

Wherein, Q is drilling riser ultimate bearing capacity [kN]; H is the buried depth [m] of seafloor soil; D is drilling riser diameter [m]; Q _gBe drilling riser ultimate bearing capacity [kN] behind the efficiency of pile groups; L is the distance [m] between the cluster well group riser pipe center; W is a cluster well group well head load [kN]; H _eFor the reasonable hammer of cluster well group riser pipe is gone into the degree of depth [m]; a ₁, b ₁And c ₁According to the definite value that obtains after the statistics that experimentizes of the seafloor soil character under different waters and the sea conditions.

The reasonable hammer of cluster well group riser pipe is gone into depth H _eBe the minimum value of h in the described step 3), its calculating formula is: $h_e=h_{\min }=\frac{L(\ln W-\ln b_1)}{c_1\ln D+{\mathrm{La}}_1}.$

The present invention is owing to take above technical scheme, it has the following advantages: because the present invention can be according to the actual conditions of different waters seabottom geology and sea situation, determine that marine cluster well group riser pipe hammers into shape into the degree of depth, satisfy the requirement of different oil drilling technology, both reduced because of riser pipe and gone into the marine accident that the mud degree of depth causes, avoid economic waste again, reached not only safety but also economic purpose.

The specific embodiment

Below in conjunction with embodiment, the present invention is described in detail.

The inventive method comprises the steps:

1) hammer the seafloor soil parameter and the drilling engineering parameter of the position, well site that collects into depth control system into shape according to cluster well group drilling riser, calculate drilling riser ultimate bearing capacity Q, wherein the seafloor soil parameter comprises the data such as buried depth of seafloor soil; Drilling engineering parameter comprises the data such as distance, preventer load and surface pipe weight between drilling riser diameter, the cluster well group riser pipe center.The calculation expression of drilling riser ultimate bearing capacity Q:

$Q=b_{1}D\·e^{a_{1}h}---\left(1\right)$

Wherein,

Q is drilling riser ultimate bearing capacity [kN];

H is the buried depth [m] of seafloor soil;

D is drilling riser diameter [m];

b ₁Be design factor;

a ₁Be design factor.

2) because the distance between the cluster well group riser pipe is 1.5～2.0 meters, so little distance can cause the seafloor soil generation efficiency of pile groups between the riser pipe in the piling construction process, the moisture content that causes soil between the riser pipe descends, and compactness increases, and ultimate bearing capacity increases.According to from the distance between the formula well group riser pipe, calculate in the piling process seafloor soil stress distribution situation between the following drilling riser of mud line, determine the drilling riser bearing capacity Q after a clump of piles responds in the piling construction process _gRelevant with the buried depth of seafloor soil, riser pipe bearing capacity Q _gCalculation expression be:

$Q_g=b_1{D}^{c_1\frac{h}{L}}\·e^{a_{1}h}---\left(2\right)$

Wherein,

Q _gBe drilling riser ultimate bearing capacity [kN] behind the efficiency of pile groups;

H is the buried depth [m] of seafloor soil;

D is drilling riser diameter [m];

L is the distance [m] between the cluster well group riser pipe center;

c ₁Be design factor.

Above-mentioned a ₁, b ₁And c ₁According to seafloor soil character under different waters and the sea conditions experimentize the statistics after obtain, be definite value.

3) according to marine cluster well group drilling riser ultimate bearing capacity Q behind the efficiency of pile groups _g, in conjunction with marine cluster well group well head load W (preventer load+surface pipe weight) size, when satisfying Q _gDuring 〉=W condition, get minimum seafloor soil buried depth value h _MinHammer into shape into degree of depth h as rational cluster well group riser pipe _e

By Q _g〉=W in conjunction with (2) formula, draws: $h\≥\frac{L(\ln W-\ln b_1)}{c_1\ln D+{\mathrm{La}}_1},$

Work as Q _gDuring=W, $\frac{L(\ln W-\ln b_1)}{c_1\ln D+{\mathrm{La}}_1}=h_{\min },$

Then $h_e=h_{\min }=\frac{L(\ln W-\ln b_1)}{c_1\ln D+{\mathrm{La}}_1}.$

Wherein,

W is cluster well group well head load=preventer load+surface pipe weight [kN];

h _cFor rational cluster well group riser pipe is hammered into shape into the degree of depth [m].

Claims (2)

1, a kind of control method of reasonable driving depth of offshore cluster well group risers, it is characterized in that: it comprises the steps:

1) hammer the seafloor soil parameter and the drilling engineering parameter of the position, well site that collects into depth control system into shape according to cluster well group drilling riser, the formula that calculates drilling riser ultimate bearing capacity Q is:

$Q=b_{1}D\·e^{a_{1}h}$

2), calculate drilling riser ultimate bearing capacity Q behind the efficiency of pile groups according to the distance between the cluster well group riser pipe _gFormula be: $Q_g=b_1{D}^{c_1\frac{h}{L}}\·e^{a_{1}h}$

3) according to step 2), and, work as Q in conjunction with marine cluster well group well head loading force W _gDuring 〉=W, the reasonable hammer that obtains cluster well group riser pipe is gone into depth H _e

Then $h\≥\frac{L(\ln W-\ln b_1)}{c_1\ln D+{\mathrm{La}}_1};$

Wherein,

Q is drilling riser ultimate bearing capacity [kN];

H is the buried depth [m] of seafloor soil;

D is drilling riser diameter [m];

Q _gBe drilling riser ultimate bearing capacity [kN] behind the efficiency of pile groups;

L is the distance [m] between the cluster well group riser pipe center;

W is from formula well group well head load [kN];

H _eFor the reasonable hammer of cluster well group riser pipe is gone into the degree of depth [m];

a ₁, b ₁And c ₁According to the definite value that obtains after the statistics that experimentizes of character on the seabed under different waters and the sea conditions.

2, the control method of a kind of reasonable driving depth of offshore cluster well group risers according to claim 1 is characterized in that: go into depth H from the reasonable hammer of formula well group riser pipe _eBe the minimum value of h in the described step 3), its calculating formula is:

$h_e=h_{\min }=\frac{L(\ln W-\ln b_1)}{c_1\ln D+{\mathrm{La}}_1}.$