declare  @assay  table (sampleid varchar(255),projectcode varchar(255),  loaddate varchar(255), sampfrom float, sampto float,[value3] float)
insert into @assay  (sampleid,projectcode, loaddate, sampfrom, [sampto],[value3]) values ('UZ-001', 'uz','2017-02-10 17:57:55.707', 5, 10,22)
insert into @assay  (sampleid, projectcode,loaddate, sampfrom, [sampto],[value3]) values ('UZ-001', 'uz','2017-02-17 17:57:55.707', 10, 22,32)
insert into @assay  (sampleid,projectcode, loaddate, sampfrom, [sampto],[value3]) values ('UZ-001','uz', '2017-02-17 17:57:55.707', 50, 52,32)
insert into @assay  (sampleid,projectcode, loaddate, sampfrom, [sampto],[value3]) values ('uz-002', 'uz','2017-02-17 17:57:55.707', 0, 40,100)
insert into @assay  (sampleid, projectcode,loaddate, sampfrom, [sampto],[value3]) values ('uz-002','uz', '2017-02-17 17:57:55.707', 50, 80,100)
select * from @assay where cast([LOADDATE] as date) between '13-feb-2017' and '20-oct-2017'

(max(sampto)-min(SAMPFROM))

select 
скважина
,sum(длина)

from
   (select (max(sampto)-min(SAMPFROM)) as длина 
....)
as t
group by скважина

With [Сначала] as 
(Select projectcode,max(sampto)-min(SAMPFROM) as [ДлинаУчасткаСкважины] From @assay
  where cast([LOADDATE] as date) between '13-feb-2017' and '20-oct-2017'
  Group by sampleid,projectcode)

Select projectcode,sum([ДлинаУчасткаСкважины]) as [ДлинаСкважины] From [Сначала]
 Group by projectcode

 Select pp.PROJECTCODE,pp.DESCRIPTION,
a.GeolLenght,
b.SendSample, c.assay, TakenSample 
From 
(
 select  dd.PROJECTCODE as x_project,
sum(cast((case when name = 'totaldrilldepth' then value end) as float)) as GeolLenght 
from drillingdetail dd 
where cast([DRILLINGDATE] as date) between '13-feb-2017' and '20-feb-2017'
 group by PROJECTCODE
) a
full join (
 select  s.PROJECTCODE as x_project,
count(sd.sampleid) as SendSample 
from  SAMPLEDESPATCH sd left join DESPATCHSEND ds on sd.DESPATCHNO=ds.DESPATCHNO left join sample s on s.SAMPLEID=sd.SAMPLEID 
where cast([senddate] as date) between '13-feb-2017' and '20-feb-2017'
 group by PROJECTCODE
) b on a.x_project =b.x_project


full join
(Select projectcode as x_project, count(sss)assay from (select distinct s.sampleid as sss,PROJECTCODE 
from cORPSAMPLEASSAY c left join sample s on s.SAMPLEID= c.SAMPLEID 
where cast([LOADDATE] as date) between '2017-02-13' and '2017-03-10')abc
group by abc.PROJECTCODE)c on a.x_project=COALESCE(b.x_project,c.x_project)
full join (
 select  ss.PROJECTCODE as x_project,
count(ts.sampleid) as TakenSample 
from  SAMPLEDETAILS ts  left join sample ss on ss.SAMPLEID=ts.SAMPLEID 
where cast((case when name = 'SampDateTaken' then value end) as date) between '13-feb-2017' and '20-feb-2017'  
 group by ss.PROJECTCODE
) t on   t.x_project=COALESCE(a.x_project,b.x_project,c.x_project)
left join PROJECT pp on pp.PROJECTCODE=c.x_project or pp.PROJECTCODE=b.x_project or pp.PROJECTCODE=a.x_project or pp.PROJECTCODE=t.x_project

group by pp.PROJECTCODE,a.GeolLenght,pp.DESCRIPTION,
b.SendSample, c.assay,TakenSample  
order by pp.DESCRIPTION